1
|
Kalkowska DA, Wassilak SGF, Wiesen E, Burns CC, Pallansch MA, Badizadegan K, Thompson KM. Coordinated global cessation of oral poliovirus vaccine use: Options and potential consequences. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2024; 44:366-378. [PMID: 37344934 PMCID: PMC10733544 DOI: 10.1111/risa.14158] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/23/2023]
Abstract
Due to the very low, but nonzero, paralysis risks associated with the use of oral poliovirus vaccine (OPV), eradicating poliomyelitis requires ending all OPV use globally. The Global Polio Eradication Initiative (GPEI) coordinated cessation of Sabin type 2 OPV (OPV2 cessation) in 2016, except for emergency outbreak response. However, as of early 2023, plans for cessation of bivalent OPV (bOPV, containing types 1 and 3 OPV) remain undefined, and OPV2 use for outbreak response continues due to ongoing transmission of type 2 polioviruses and reported type 2 cases. Recent development and use of a genetically stabilized novel type 2 OPV (nOPV2) leads to additional potential vaccine options and increasing complexity in strategies for the polio endgame. Prior applications of integrated global risk, economic, and poliovirus transmission modeling consistent with GPEI strategic plans that preceded OPV2 cessation explored OPV cessation dynamics and the evaluation of options to support globally coordinated risk management efforts. The 2022-2026 GPEI strategic plan highlighted the need for early bOPV cessation planning. We review the published modeling and explore bOPV cessation immunization options as of 2022, assuming that the GPEI partners will not support restart of the use of any OPV type in routine immunization after a globally coordinated cessation of such use. We model the potential consequences of globally coordinating bOPV cessation in 2027, as anticipated in the 2022-2026 GPEI strategic plan. We do not find any options for bOPV cessation likely to succeed without a strategy of bOPV intensification to increase population immunity prior to cessation.
Collapse
Affiliation(s)
| | - Steven G. F. Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Eric Wiesen
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Cara C. Burns
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Mark A. Pallansch
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | | |
Collapse
|
2
|
Thompson KM, Badizadegan K. Evolution of global polio eradication strategies: targets, vaccines, and supplemental immunization activities (SIAs). Expert Rev Vaccines 2024; 23:597-613. [PMID: 38813792 DOI: 10.1080/14760584.2024.2361060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 05/24/2024] [Indexed: 05/31/2024]
Abstract
BACKGROUND Despite multiple revisions of targets and timelines in polio eradication plans since 1988, including changes in supplemental immunization activities (SIAs) that increase immunity above routine immunization (RI) coverage, poliovirus transmission continues as of 2024. METHODS We reviewed polio eradication plans and Global Polio Eradication Initiative (GPEI) annual reports and budgets to characterize key phases of polio eradication, the evolution of poliovirus vaccines, and the role of SIAs. We used polio epidemiology to provide context for successes and failures and updated prior modeling to show the contribution of SIAs in achieving and maintaining low polio incidence compared to expected incidence for the counterfactual of RI only. RESULTS We identified multiple phases of polio eradication that included shifts in targets and timelines and the introduction of different poliovirus vaccines, which influenced polio epidemiology. Notable shifts occurred in GPEI investments in SIAs since 2001, particularly since 2016. Modeling results suggest that SIAs play(ed) a key role in increasing (and maintaining) high population immunity to levels required to eradicate poliovirus transmission globally. CONCLUSIONS Shifts in polio eradication strategy and poliovirus vaccine usage in SIAs provide important context for understanding polio epidemiology, delayed achievement of polio eradication milestones, and complexity of the polio endgame.
Collapse
|
3
|
Kalkowska DA, Badizadegan K, Thompson KM. Outbreak management strategies for cocirculation of multiple poliovirus types. Vaccine 2023:S0264-410X(23)00429-2. [PMID: 37121801 DOI: 10.1016/j.vaccine.2023.04.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/11/2023] [Indexed: 05/02/2023]
Abstract
Prior modeling studies showed that current outbreak management strategies are unlikely to stop outbreaks caused by type 1 wild polioviruses (WPV1) or circulating vaccine-derived polioviruses (cVDPVs) in many areas, and suggested increased risks of outbreaks with cocirculation of more than one type of poliovirus. The surge of type 2 poliovirus transmission that began in 2019 and continues to date, in conjunction with decreases in preventive supplemental immunization activities (SIAs) for poliovirus types 1 and 3, has led to the emergence of several countries with cocirculation of more than one type of poliovirus. Response to these emerging cocirculation events is theoretically straightforward, but the different formulations, types, and inventories of oral poliovirus vaccines (OPVs) available for outbreak response present challenging practical questions. In order to demonstrate the implications of using different vaccine options and outbreak campaign strategies, we applied a transmission model to a hypothetical population with conditions similar to populations currently experiencing outbreaks of cVDPVs of both types 1 and 2. Our results suggest prevention of the largest number of paralytic cases occurs when using (1) trivalent OPV (tOPV) (or coadministering OPV formulations for all three types) until one poliovirus outbreak type dies out, followed by (2) using a type-specific OPV until the remaining poliovirus outbreak type also dies out. Using tOPV first offers a lower overall expected cost, but this option may be limited by the willingness to expose populations to type 2 Sabin OPV strains. For strategies that use type 2 novel OPV (nOPV2) concurrently administered with bivalent OPV (bOPV, containing types 1 and 3 OPV) emerges as a leading option, but questions remain about feasibility, logistics, type-specific take rates, and coadministration costs.
Collapse
|
4
|
Kalkowska DA, Wassilak SGF, Wiesen E, F Estivariz C, Burns CC, Badizadegan K, Thompson KM. Complexity of options related to restarting oral poliovirus vaccine (OPV) in national immunization programs after OPV cessation. Gates Open Res 2023; 7:55. [PMID: 37547300 PMCID: PMC10403636 DOI: 10.12688/gatesopenres.14511.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/09/2023] [Indexed: 08/08/2023] Open
Abstract
Background: The polio eradication endgame continues to increase in complexity. With polio cases caused by wild poliovirus type 1 and circulating vaccine-derived polioviruses of all three types (1, 2 and 3) reported in 2022, the number, formulation, and use of poliovirus vaccines poses challenges for national immunization programs and vaccine suppliers. Prior poliovirus transmission modeling of globally-coordinated type-specific cessation of oral poliovirus vaccine (OPV) assumed creation of Sabin monovalent OPV (mOPV) stockpiles for emergencies and explored the potential need to restart OPV if the world reached a specified cumulative threshold number of cases after OPV cessation. Methods: We document the actual experience of type 2 OPV (OPV2) cessation and reconsider prior modeling assumptions related to OPV restart. We develop updated decision trees of national immunization options for poliovirus vaccines considering different possibilities for OPV restart. Results: While OPV restart represented a hypothetical situation for risk management and contingency planning to support the 2013-2018 Global Polio Eradication Initiative (GPEI) Strategic Plan, the actual epidemiological experience since OPV2 cessation raises questions about what, if any, trigger(s) could lead to restarting the use of OPV2 in routine immunization and/or plans for potential future restart of type 1 and 3 OPV after their respective cessation. The emergency use listing of a genetically stabilized novel type 2 OPV (nOPV2) and continued evaluation of nOPV for types 1 and/or 3 add further complexity by increasing the combinations of possible OPV formulations for OPV restart. Conclusions: Expanding on a 2019 discussion of the logistical challenges and implications of restarting OPV, we find a complex structure of the many options and many issues related to OPV restart decisions and policies as of early 2023. We anticipate many challenges for forecasting prospective vaccine supply needs during the polio endgame due to increasing potential combinations of poliovirus vaccine choices.
Collapse
Affiliation(s)
| | - Steven GF Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Eric Wiesen
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Concepcion F Estivariz
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Cara C Burns
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, USA, Atlanta, GA, USA
| | | | | |
Collapse
|
5
|
Darwar R, Biya O, Greene SA, Jorba J, Al Safadi M, Franka R, Wiesen E, Durry E, Pallansch MA. Assessing country compliance with circulating vaccine-derived poliovirus type 2 outbreak response standard operating procedures: April 2016 to December 2020. Vaccine 2023; 41 Suppl 1:A25-A34. [PMID: 36863925 DOI: 10.1016/j.vaccine.2023.02.060] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 02/17/2023] [Accepted: 02/20/2023] [Indexed: 03/04/2023]
Abstract
BACKGROUND Trivalent oral poliovirus vaccine (tOPV) was globally replaced with bivalent oral poliovirus vaccine (bOPV) in April 2016 ("the switch"). Many outbreaks of paralytic poliomyelitis associated with type 2 circulating vaccine-derived poliovirus (cVDPV2) have been reported since this time. The Global Polio Eradication Initiative (GPEI) developed standard operating procedures (SOPs) to guide countries experiencing cVDPV2 outbreaks to implement timely and effective outbreak response (OBR). To assess the possible role of compliance with SOPs in successfully stopping cVDPV2 outbreaks, we analyzed data on critical timelines in the OBR process. METHODS Data were collected on all cVDPV2 outbreaks detected for the period April 1, 2016 and December 31, 2020 and all outbreak responses to those outbreaks between April 1, 2016 and December 31, 2021. We conducted secondary data analysis using the GPEI Polio Information System database, records from the Anonymized Institution Poliovirus Laboratory, and meeting minutes of the monovalent OPV2 (mOPV2) Advisory Group. Date of notification of circulating virus was defined as Day 0 for this analysis. Extracted process variables were compared with indicators in the GPEI SOP version 3.1. RESULTS One hundred and eleven cVDPV2 outbreaks resulting from 67 distinct cVDPV2 emergences were reported during April 1, 2016-December 31, 2020, affecting 34 countries across four World Health Organization Regions. Out of 65 OBRs with the first large-scale campaign (R1) conducted after Day 0, only 12 (18.5%) R1s were conducted by the target of 28 days after Day 0. Of the 89 OBRs with the second large-scale campaign (R2) conducted after Day 0, 30 (33.7%) R2s were conducted by the target of 56 days after Day 0. Twenty-three (31.9%) of the 72 outbreaks with isolates dated after Day 0 were stopped within the 120-day target. CONCLUSION Since "the switch", delays in OBR implementation were evident in many countries, which may be related to the persistence of cVDPV2 outbreaks >120 days. To achieve timely and effective response, countries should follow GPEI OBR guidelines.
Collapse
Affiliation(s)
- Roopa Darwar
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, United States.
| | - Oladayo Biya
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, United States.
| | - Sharon A Greene
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, United States.
| | - Jaume Jorba
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, United States.
| | - Mohammad Al Safadi
- Polio Eradication Department, World Health Organization, Geneva, Switzerland.
| | - Richard Franka
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, United States.
| | - Eric Wiesen
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, United States.
| | - Elias Durry
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, United States.
| | - Mark A Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, United States.
| |
Collapse
|
6
|
Liu S, Lu W, Ma S, Guo H, Zhang Z, Li X. Comparison of the neutralizing activities of antibodies in clinical sera against both Sabin and wild-type polio pseudoviruses. J Virol Methods 2021; 300:114376. [PMID: 34826519 DOI: 10.1016/j.jviromet.2021.114376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/18/2021] [Accepted: 11/22/2021] [Indexed: 11/30/2022]
Abstract
The cost-effectiveness of the Sabin inactivated poliovirus vaccine derived from the Sabin strains (S-IPV) and its reduced biosecurity risks during its manufacture make it the vaccine of choice over the IPVs derived from wild-type polioviruses. However, it is difficult to evaluate whether S-IPVs can achieve wild-type poliovirus containment in China, making its development there less attractive. To facilitate the development and adoption of S-IPVs in China, the aim of this study was to develop an alternative neutralizing assay using either a polio pseudovirus derived from a Sabin strain (S-pNA) or one derived from a wild-type strain (w-pNA) to replace the conventional neutralizing assay which uses live polioviruses. A total of 100 sera were collected from children immunized with an oral poliovirus vaccine and their antibody titers were assessed by both the S-pNA and w-pNA. The results showed that this method was feasible for the quantification of neutralizing antibody activities in the sera of the vaccinated individuals. The Wilcoxon signed-rank sum test indicated that the neutralizing antibody titers obtained against the Sabin strains were higher than those obtained with the wild-type strains for types 1 and 3, while for type 2, the titers against the wild-type strains were higher than those against the Sabin strains (p < 0.001 for all three types). It is hoped that this assay could be used to assess whether immune sera by the S-IPV possess adequate neutralizing capacity against both attenuated and wild-type poliovirus strains.
Collapse
Affiliation(s)
- Shaohua Liu
- National Vaccine & Serum Institute, Beijing, China
| | - Weiwei Lu
- National Vaccine & Serum Institute, Beijing, China
| | - Shuhua Ma
- National Vaccine & Serum Institute, Beijing, China
| | - Huijie Guo
- National Vaccine & Serum Institute, Beijing, China
| | | | - Xiuling Li
- National Vaccine & Serum Institute, Beijing, China; Shanghai Institute of Biological Products Co. LTD, China.
| |
Collapse
|
7
|
Mbaeyi C, Moran T, Wadood Z, Ather F, Sykes E, Nikulin J, Al Safadi M, Stehling-Ariza T, Zomahoun L, Ismaili A, Abourshaid N, Asghar H, Korukluoglu G, Duizer E, Ehrhardt D, Burns CC, Sharaf M. Stopping a polio outbreak in the midst of war: Lessons from Syria. Vaccine 2021; 39:3717-3723. [PMID: 34053791 DOI: 10.1016/j.vaccine.2021.05.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 05/05/2021] [Accepted: 05/17/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND Outbreaks of circulating vaccine-derived polioviruses (cVDPVs) pose a threat to the eventual eradication of all polioviruses. In 2017, an outbreak of cVDPV type 2 (cVDPV2) occurred in the midst of a war in Syria. We describe vaccination-based risk factors for and the successful response to the outbreak. METHODS We performed a descriptive analysis of cVDPV2 cases and key indicators of poliovirus surveillance and vaccination activities during 2016-2018. In the absence of reliable subnational coverage data, we used the caregiver-reported vaccination status of children with non-polio acute flaccid paralysis (AFP) as a proxy for vaccination coverage. We then estimated the relative odds of being unvaccinated against polio, comparing children in areas affected by the outbreak to children in other parts of Syria in order to establish the presence of poliovirus immunity gaps in outbreak affected areas. FINDINGS A total of 74 cVDPV2 cases were reported, with paralysis onset ranging from 3 March to 21 September 2017. All but three cases were reported from Deir-ez-Zor governorate and 84% had received < 3 doses of oral poliovirus vaccine (OPV). After adjusting for age and sex, non-polio AFP case-patients aged 6-59 months in outbreak-affected areas had 2.5 (95% CI: 1.1-5.7) increased odds of being unvaccinated with OPV compared with non-polio AFP case-patients in the same age group in other parts of Syria. Three outbreak response rounds of monovalent OPV type 2 (mOPV2) vaccination were conducted, with governorate-level coverage mostly exceeding 80%. INTERPRETATION Significant declines in both national and subnational polio vaccination coverage, precipitated by war and a humanitarian crisis, led to a cVDPV2 outbreak in Syria that was successfully contained following three rounds of mOPV2 vaccination.
Collapse
Affiliation(s)
- Chukwuma Mbaeyi
- United States Centers for Disease Control and Prevention, 1600 Clifton Rd. NE, Atlanta, GA 30329, USA.
| | - Thomas Moran
- World Health Organization Headquarters, Avenue Appia 20, 1202 Geneva, Switzerland
| | - Zubair Wadood
- World Health Organization Headquarters, Avenue Appia 20, 1202 Geneva, Switzerland
| | - Fazal Ather
- Middle East and North Africa Office, United Nations Children's Fund, Abdulqader Al-Abed Street, Building No. 15, Tla'a Al-Ali, Amman, Jordan
| | - Emma Sykes
- World Health Organization, Regional Office for the Eastern Mediterranean, Mohammad Jamjoum Street, Ministry of Interior Circle Building No. 5, P.O. Box 811547, Amman 11181, Jordan
| | - Joanna Nikulin
- World Health Organization, Regional Office for the Eastern Mediterranean, Mohammad Jamjoum Street, Ministry of Interior Circle Building No. 5, P.O. Box 811547, Amman 11181, Jordan
| | - Mohammad Al Safadi
- World Health Organization Headquarters, Avenue Appia 20, 1202 Geneva, Switzerland
| | - Tasha Stehling-Ariza
- United States Centers for Disease Control and Prevention, 1600 Clifton Rd. NE, Atlanta, GA 30329, USA
| | - Laurel Zomahoun
- World Health Organization Headquarters, Avenue Appia 20, 1202 Geneva, Switzerland
| | - Abdelkarim Ismaili
- World Health Organization, Regional Office for the Eastern Mediterranean, Mohammad Jamjoum Street, Ministry of Interior Circle Building No. 5, P.O. Box 811547, Amman 11181, Jordan
| | - Nidal Abourshaid
- Syria Country Office, United Nations Children's Fund, East Mazzeh, Al Shafiee St., Damascus, Syria
| | - Humayun Asghar
- World Health Organization, Regional Office for the Eastern Mediterranean, Mohammad Jamjoum Street, Ministry of Interior Circle Building No. 5, P.O. Box 811547, Amman 11181, Jordan
| | - Gulay Korukluoglu
- Public Health Institutions of Turkey, Adnan Saygun Cad. No. 55, F Blok 06100 Sihhiye, Ankara, Turkey
| | - Erwin Duizer
- National Polio Laboratory, Centre for Infectious Disease Control, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA, Bilthoven, the Netherlands
| | - Derek Ehrhardt
- United States Centers for Disease Control and Prevention, 1600 Clifton Rd. NE, Atlanta, GA 30329, USA
| | - Cara C Burns
- United States Centers for Disease Control and Prevention, 1600 Clifton Rd. NE, Atlanta, GA 30329, USA
| | - Magdi Sharaf
- World Health Organization, Regional Office for the Eastern Mediterranean, Mohammad Jamjoum Street, Ministry of Interior Circle Building No. 5, P.O. Box 811547, Amman 11181, Jordan
| |
Collapse
|
8
|
Thompson KM, Kalkowska DA, Badizadegan K. Hypothetical emergence of poliovirus in 2020: part 2. exploration of the potential role of vaccines in control and eradication. Expert Rev Vaccines 2021; 20:449-460. [PMID: 33599178 DOI: 10.1080/14760584.2021.1891889] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES The emergence of human pathogens with pandemic potential motivates rapid vaccine development. We explore the role of vaccines in control and eradication of a novel emerging pathogen. METHODS We hypothetically simulate emergence of a novel wild poliovirus (nWPV) in 2020 assuming an immunologically naïve population. Assuming different nonpharmaceutical interventions (NPIs), we explore the impacts of vaccines resembling serotype-specific oral poliovirus vaccine (OPV), novel OPV (nOPV), or inactivated poliovirus vaccine (IPV). RESULTS Vaccines most effectively change the trajectory of an emerging disease when disseminated early, rapidly, and widely in the background of ongoing strict NPIs, unless the NPIs successfully eradicate the emerging pathogen before it establishes endemic transmission. Without strict NPIs, vaccines primarily reduce the burden of disease in the remaining susceptible individuals and in new birth cohorts. Live virus vaccines that effectively compete with the nWPVs can reduce disease burdens more than other vaccines. When relaxation of existing NPIs occurs at the time of vaccine introduction, nWPV transmission can counterintuitively increase in the short term. CONCLUSIONS Vaccines can increase the probability of disease eradication in the context of strict NPIs. However, successful eradication will depend on specific immunization strategies used and a global commitment to eradication.
Collapse
|
9
|
Kalkowska DA, Pallansch MA, F. Wassilak SG, Cochi SL, Thompson KM. Global Transmission of Live Polioviruses: Updated Dynamic Modeling of the Polio Endgame. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2021; 41:248-265. [PMID: 31960533 PMCID: PMC7787008 DOI: 10.1111/risa.13447] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/30/2019] [Accepted: 12/02/2019] [Indexed: 05/05/2023]
Abstract
Nearly 20 years after the year 2000 target for global wild poliovirus (WPV) eradication, live polioviruses continue to circulate with all three serotypes posing challenges for the polio endgame. We updated a global differential equation-based poliovirus transmission and stochastic risk model to include programmatic and epidemiological experience through January 2020. We used the model to explore the likely dynamics of poliovirus transmission for 2019-2023, which coincides with a new Global Polio Eradication Initiative Strategic Plan. The model stratifies the global population into 72 blocks, each containing 10 subpopulations of approximately 10.7 million people. Exported viruses go into subpopulations within the same block and within groups of blocks that represent large preferentially mixing geographical areas (e.g., continents). We assign representative World Bank income levels to the blocks along with polio immunization and transmission assumptions, which capture some of the heterogeneity across countries while still focusing on global poliovirus transmission dynamics. We also updated estimates of reintroduction risks using available evidence. The updated model characterizes transmission dynamics and resulting polio cases consistent with the evidence through 2019. Based on recent epidemiological experience and prospective immunization assumptions for the 2019-2023 Strategic Plan, the updated model does not show successful eradication of serotype 1 WPV by 2023 or successful cessation of oral poliovirus vaccine serotype 2-related viruses.
Collapse
Affiliation(s)
| | - Mark A. Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Steven G. F. Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Stephen L. Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | |
Collapse
|
10
|
Thompson KM, Kalkowska DA. Potential Future Use, Costs, and Value of Poliovirus Vaccines. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2021; 41:349-363. [PMID: 32645244 PMCID: PMC7984393 DOI: 10.1111/risa.13557] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/22/2020] [Indexed: 05/06/2023]
Abstract
Countries face different poliovirus risks, which imply different benefits associated with continued and future use of oral poliovirus vaccine (OPV) and/or inactivated poliovirus vaccine (IPV). With the Global Polio Eradication Initiative (GPEI) continuing to extend its timeline for ending the transmission of all wild polioviruses and to introduce new poliovirus vaccines, the polio vaccine supply chain continues to expand in complexity. The increased complexity leads to significant uncertainty about supply and costs. Notably, the strategy of phased OPV cessation of all three serotypes to stop all future incidence of poliomyelitis depends on successfully stopping the transmission of all wild polioviruses. Countries also face challenges associated with responding to any outbreaks that occur after OPV cessation, because stopping transmission of such outbreaks requires reintroducing the use of the stopped OPV in most countries. National immunization program leaders will likely consider differences in their risks and willingness-to-pay for risk reduction as they evaluate their investments in current and future polio vaccination. Information about the costs and benefits of future poliovirus vaccines, and discussion of the complex situation that currently exists, should prove useful to national, regional, and global decisionmakers and support health economic modeling. Delays in achieving polio eradication combined with increasing costs of poliovirus vaccines continue to increase financial risks for the GPEI.
Collapse
|
11
|
Thompson KM, Kalkowska DA. Review of poliovirus modeling performed from 2000 to 2019 to support global polio eradication. Expert Rev Vaccines 2020; 19:661-686. [PMID: 32741232 PMCID: PMC7497282 DOI: 10.1080/14760584.2020.1791093] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/22/2020] [Indexed: 01/03/2023]
Abstract
INTRODUCTION Over the last 20 years (2000-2019) the partners of the Global Polio Eradication Initiative (GPEI) invested in the development and application of mathematical models of poliovirus transmission as well as economics, policy, and risk analyses of polio endgame risk management options, including policies related to poliovirus vaccine use during the polio endgame. AREAS COVERED This review provides a historical record of the polio studies published by the three modeling groups that primarily performed the bulk of this work. This review also systematically evaluates the polio transmission and health economic modeling papers published in English in peer-reviewed journals from 2000 to 2019, highlights differences in approaches and methods, shows the geographic coverage of the transmission modeling performed, identified common themes, and discusses instances of similar or conflicting insights or recommendations. EXPERT OPINION Polio modeling performed during the last 20 years substantially impacted polio vaccine choices, immunization policies, and the polio eradication pathway. As the polio endgame continues, national preferences for polio vaccine formulations and immunization strategies will likely continue to change. Future modeling will likely provide important insights about their cost-effectiveness and their relative benefits with respect to controlling polio and potentially achieving and maintaining eradication.
Collapse
|
12
|
Zaman K, Anand A. Complex task to estimate immune responses to various poliovirus vaccines and vaccination schedules. THE LANCET. INFECTIOUS DISEASES 2019; 19:1043-1045. [PMID: 31350191 PMCID: PMC10846467 DOI: 10.1016/s1473-3099(19)30322-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 06/07/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Khalequ Zaman
- International Centre for Diarrhoeal Disease Research Bangladesh, Dhaka 1212, Bangladesh.
| | - Abhijeet Anand
- US Centers for Disease Control and Prevention, Atlanta, GA, USA
| |
Collapse
|
13
|
Duintjer Tebbens RJ, Thompson KM. Evaluation of Proactive and Reactive Strategies for Polio Eradication Activities in Pakistan and Afghanistan. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2019; 39:389-401. [PMID: 30239026 PMCID: PMC7857157 DOI: 10.1111/risa.13194] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/21/2018] [Accepted: 08/24/2018] [Indexed: 05/21/2023]
Abstract
Only Pakistan and Afghanistan reported any polio cases caused by serotype 1 wild polioviruses (WPV1s) in 2017. With the dwindling cases in both countries and pressure to finish eradication with the least possible resources, a danger exists of inappropriate prioritization of efforts between the two countries and insufficient investment in the two countries to finish the job. We used an existing differential-equation-based poliovirus transmission and oral poliovirus (OPV) evolution model to simulate a proactive strategy to stop transmission, and different hypothetical reactive strategies that adapt the quality of supplemental immunization activities (SIAs) in response to observed polio cases in Pakistan and Afghanistan. To account for the delay in perception and adaptation, we related the coverage of the SIAs in high-risk, undervaccinated subpopulations to the perceived (i.e., smoothed) polio incidence. Continuation of the current frequency and quality of SIAs remains insufficient to eradicate WPV1 in Pakistan and Afghanistan. Proactive strategies that significantly improve and sustain SIA quality lead to WPV1 eradication and the prevention of circulating vaccine-derived poliovirus (cVDPV) outbreaks. Reactive vaccination efforts that adapt moderately quickly and independently to changes in polio incidence in each country may succeed in WPV1 interruption after several cycles of outbreaks, or may interrupt WPV1 transmission in one country but subsequently import WPV1 from the other country or enable the emergence of cVDPV outbreaks. Reactive vaccination efforts that adapt independently and either more rapidly or more slowly to changes in polio incidence in each country may similarly fail to interrupt WPV1 transmission and result in oscillations of the incidence. Reactive strategies that divert resources to the country of highest priority may lead to alternating large outbreaks. Achieving WPV1 eradication and subsequent successful OPV cessation in Pakistan and Afghanistan requires proactive and sustained efforts to improve vaccination intensity in under-vaccinated subpopulations while maintaining high population immunity elsewhere.
Collapse
|
14
|
Duintjer Tebbens RJ, Pallansch MA, Cochi SL, Ehrhardt D, Farag N, Hadler S, Hampton LM, Martinez M, Wassilak SG, Thompson KM. Modeling Poliovirus Transmission in Pakistan and Afghanistan to Inform Vaccination Strategies in Undervaccinated Subpopulations. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2018; 38:1701-1717. [PMID: 29314143 PMCID: PMC7879700 DOI: 10.1111/risa.12962] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 11/18/2017] [Accepted: 11/22/2017] [Indexed: 05/11/2023]
Abstract
Due to security, access, and programmatic challenges in areas of Pakistan and Afghanistan, both countries continue to sustain indigenous wild poliovirus (WPV) transmission and threaten the success of global polio eradication and oral poliovirus vaccine (OPV) cessation. We fitted an existing differential-equation-based poliovirus transmission and OPV evolution model to Pakistan and Afghanistan using four subpopulations to characterize the well-vaccinated and undervaccinated subpopulations in each country. We explored retrospective and prospective scenarios for using inactivated poliovirus vaccine (IPV) in routine immunization or supplemental immunization activities (SIAs). The undervaccinated subpopulations sustain the circulation of serotype 1 WPV and serotype 2 circulating vaccine-derived poliovirus. We find a moderate impact of past IPV use on polio incidence and population immunity to transmission mainly due to (1) the boosting effect of IPV for individuals with preexisting immunity from a live poliovirus infection and (2) the effect of IPV-only on oropharyngeal transmission for individuals without preexisting immunity from a live poliovirus infection. Future IPV use may similarly yield moderate benefits, particularly if access to undervaccinated subpopulations dramatically improves. However, OPV provides a much greater impact on transmission and the incremental benefit of IPV in addition to OPV remains limited. This study suggests that despite the moderate effect of using IPV in SIAs, using OPV in SIAs remains the most effective means to stop transmission, while limited IPV resources should prioritize IPV use in routine immunization.
Collapse
Affiliation(s)
| | - Mark A. Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Stephen L. Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Derek Ehrhardt
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Noha Farag
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Stephen Hadler
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Lee M. Hampton
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Maureen Martinez
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Steve G.F Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | |
Collapse
|
15
|
Tebbens RJD, Thompson KM. Using integrated modeling to support the global eradication of vaccine-preventable diseases. SYSTEM DYNAMICS REVIEW 2018; 34:78-120. [PMID: 34552305 PMCID: PMC8455164 DOI: 10.1002/sdr.1589] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 02/11/2018] [Indexed: 05/17/2023]
Abstract
The long-term management of global disease eradication initiatives involves numerous inherently dynamic processes, health and economic trade-offs, significant uncertainty and variability, rare events with big consequences, complex and inter-related decisions, and a requirement for cooperation among a large number of stakeholders. Over the course of more than 16 years of collaborative modeling efforts to support the Global Polio Eradication Initiative, we developed increasingly complex integrated system dynamics models that combined numerous analytical approaches, including differential equation-based modeling, risk and decision analysis, discrete-event and individual-based simulation, probabilistic uncertainty and sensitivity analysis, health economics, and optimization. We discuss the central role of systems thinking and system dynamics in the overall effort and the value of integrating different modeling approaches to appropriately address the trade-offs involved in some of the policy questions. We discuss practical challenges of integrating different analytical tools and we provide our perspective on the future of integrated modeling.
Collapse
|
16
|
Duintjer Tebbens RJ, Thompson KM. Poliovirus vaccination during the endgame: insights from integrated modeling. Expert Rev Vaccines 2017; 16:577-586. [DOI: 10.1080/14760584.2017.1322514] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | - Kimberly M. Thompson
- Kid Risk, Inc., Orlando, FL, USA
- College of Medicine, University of Central Florida, Orlando, FL, USA
| |
Collapse
|
17
|
Koopman JS, Henry CJ, Park JH, Eisenberg MC, Ionides EL, Eisenberg JN. Dynamics affecting the risk of silent circulation when oral polio vaccination is stopped. Epidemics 2017; 20:21-36. [PMID: 28283373 PMCID: PMC5608688 DOI: 10.1016/j.epidem.2017.02.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 02/20/2017] [Accepted: 02/20/2017] [Indexed: 12/15/2022] Open
Abstract
Silent circulation (SC) of wild polio viruses (WPV) when oral polio vaccine (OPV) use is stopped, could threaten eradication. We analyzed a model designed to develop theory about mechanisms and factors that lead to SC and how SC risks can be assessed using surveillance data. Prolonged low-level SC emerges as a threshold phenomenon through a mechanism related to balancing contributions of different populations to the effective reproduction number. Factors that promote this mechanism are many years of inadequate vaccination efforts, ongoing waning of immunity against transmission years after last OPV or WPV infection, low transmissibility of OPV, and high transmission conditions. Analyzing acute flaccid paralysis surveillance or environmental surveillance data by themselves cannot assess the risk that an SC threshold has been passed, but new methods to analyze them jointly could do so.
Waning immunity could allow transmission of polioviruses without causing poliomyelitis by promoting silent circulation (SC). Undetected SC when oral polio vaccine (OPV) use is stopped could cause difficult to control epidemics. Little is known about waning. To develop theory about what generates SC, we modeled a range of waning patterns. We varied both OPV and wild polio virus (WPV) transmissibility, the time from beginning vaccination to reaching low polio levels, and the infection to paralysis ratio (IPR). There was longer SC when waning continued over time rather than stopping after a few years, when WPV transmissibility was higher or OPV transmissibility was lower, and when the IPR was higher. These interacted in a way that makes recent emergence of prolonged SC a possibility. As the time to reach low infection levels increased, vaccine rates needed to eliminate polio increased and a threshold was passed where prolonged low-level SC emerged. These phenomena were caused by increased contributions to the force of infection from reinfections. The resulting SC occurs at low levels that would be difficult to detect using environmental surveillance. For all waning patterns, modest levels of vaccination of adults shortened SC. Previous modeling studies may have missed these phenomena because (1) they used models with no or very short duration waning and (2) they fit models to paralytic polio case counts. Our analyses show that polio case counts cannot predict SC because nearly identical polio case count patterns can be generated by a range of waning patterns that generate different patterns of SC. We conclude that the possibility of prolonged SC is real but unquantified, that vaccinating modest fractions of adults could reduce SC risk, and that joint analysis of acute flaccid paralysis and environmental surveillance data can help assess SC risks and ensure low risks before stopping OPV.
Collapse
Affiliation(s)
- J S Koopman
- Department of Epidemiology, University of Michigan School of Public Health, United States.
| | - C J Henry
- Department of Epidemiology, University of Michigan School of Public Health, United States
| | - J H Park
- Department of Statistics, University of Michigan School of Literature, Science, and the Arts, United States
| | - M C Eisenberg
- Department of Epidemiology, University of Michigan School of Public Health, United States
| | - E L Ionides
- Department of Statistics, University of Michigan School of Literature, Science, and the Arts, United States
| | - J N Eisenberg
- Department of Epidemiology, University of Michigan School of Public Health, United States
| |
Collapse
|
18
|
Duintjer Tebbens RJ, Thompson KM. Costs and Benefits of Including Inactivated in Addition to Oral Poliovirus Vaccine in Outbreak Response After Cessation of Oral Poliovirus Vaccine Use. MDM Policy Pract 2017; 2:2381468317697002. [PMID: 30288417 PMCID: PMC6124926 DOI: 10.1177/2381468317697002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 12/02/2016] [Indexed: 01/24/2023] Open
Abstract
Background: After stopping serotype 2-containing oral poliovirus vaccine use, serotype 2 poliovirus outbreaks may still occur and require outbreak response supplemental immunization activities (oSIAs). Current oSIA plans include the use of both serotype 2 monovalent oral poliovirus vaccine (mOPV2) and inactivated poliovirus vaccine (IPV). Methods: We used an existing model to compare the effectiveness of mOPV2 oSIAs with or without IPV in response to a hypothetical postcessation serotype 2 outbreak in northwest Nigeria. We considered strategies that co-administer IPV with mOPV2, use IPV only for older age groups, or use only IPV during at least one oSIA. We considered the cost and supply implications and estimated from a societal perspective the incremental cost-effectiveness and incremental net benefits of adding IPV to oSIAs in the context of this hypothetical outbreak in 2017. Results: Adding IPV to the first or second oSIA resulted in a 4% to 6% reduction in expected polio cases compared to exclusive mOPV2 oSIAs. We found the greatest benefit of IPV use if added preemptively as a ring around the initial oSIA target population, and negligible benefit if added to later oSIAs or older age groups. We saw an increase in expected polio cases if IPV replaced mOPV2 during an oSIA. None of the oSIA strategies that included IPV for this outbreak represented a cost-effective or net beneficial intervention compared to reliance on mOPV2 only. Conclusions: While adding IPV to oSIAs results in marginal improvements in performance, the poor cost-effectiveness and current limited IPV supply make it economically unattractive for high-risk settings in which IPV does not significantly affect transmission.
Collapse
|
19
|
Duintjer Tebbens RJ, Thompson KM. The potential benefits of a new poliovirus vaccine for long-term poliovirus risk management. Future Microbiol 2016; 11:1549-1561. [DOI: 10.2217/fmb-2016-0126] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Aim: To estimate the incremental net benefits (INBs) of a hypothetical ideal vaccine with all of the advantages and no disadvantages of existing oral and inactivated poliovirus vaccines compared with current vaccines available for future outbreak response. Methods: INB estimates based on expected costs and polio cases from an existing global model of long-term poliovirus risk management. Results: Excluding the development costs, an ideal poliovirus vaccine could offer expected INBs of US$1.6 billion. The ideal vaccine yields small benefits in most realizations of long-term risks, but great benefits in low-probability–high-consequence realizations. Conclusion: New poliovirus vaccines may offer valuable insurance against long-term poliovirus risks and new vaccine development efforts should continue as the world gathers more evidence about polio endgame risks.
Collapse
|
20
|
Thompson KM, Odahowski CL, Goodson JL, Reef SE, Perry RT. Synthesis of Evidence to Characterize National Measles and Rubella Exposure and Immunization Histories. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2016; 36:1427-1458. [PMID: 26249328 DOI: 10.1111/risa.12454] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 05/26/2015] [Accepted: 05/26/2015] [Indexed: 06/04/2023]
Abstract
Population immunity depends on the dynamic levels of immunization coverage that countries achieve over time and any transmission of viruses that occur within the population that induce immunity. In the context of developing a dynamic transmission model for measles and rubella to support analyses of future immunization policy options, we assessed the model inputs required to reproduce past behavior and to provide some confidence about model performance at the national level. We reviewed the data available from the World Health Organization (WHO) and existing measles and rubella literature for evidence of historical reported routine and supplemental immunization activities and reported cases and outbreaks. We constructed model input profiles for 180 WHO member states and three other areas to support disease transmission model development and calibration. The profiles demonstrate the significant variability in immunization strategies used historically by regions and member states and the epidemiological implications of these historical choices. The profiles provide a historical perspective on measles and rubella immunization globally at the national level, and they may help immunization program managers identify existing immunity and/or knowledge gaps.
Collapse
Affiliation(s)
- Kimberly M Thompson
- Kid Risk, Inc, Orlando, FL, USA
- University of Central Florida, College of Medicine, Orlando, FL, USA
| | | | - James L Goodson
- Global Immunization Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Susan E Reef
- Global Immunization Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | |
Collapse
|
21
|
Thompson KM, Duintjer Tebbens RJ. Framework for Optimal Global Vaccine Stockpile Design for Vaccine-Preventable Diseases: Application to Measles and Cholera Vaccines as Contrasting Examples. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2016; 36:1487-1509. [PMID: 25109229 DOI: 10.1111/risa.12265] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Managing the dynamics of vaccine supply and demand represents a significant challenge with very high stakes. Insufficient vaccine supplies can necessitate rationing, lead to preventable adverse health outcomes, delay the achievements of elimination or eradication goals, and/or pose reputation risks for public health authorities and/or manufacturers. This article explores the dynamics of global vaccine supply and demand to consider the opportunities to develop and maintain optimal global vaccine stockpiles for universal vaccines, characterized by large global demand (for which we use measles vaccines as an example), and nonuniversal (including new and niche) vaccines (for which we use oral cholera vaccine as an example). We contrast our approach with other vaccine stockpile optimization frameworks previously developed for the United States pediatric vaccine stockpile to address disruptions in supply and global emergency response vaccine stockpiles to provide on-demand vaccines for use in outbreaks. For measles vaccine, we explore the complexity that arises due to different formulations and presentations of vaccines, consideration of rubella, and the context of regional elimination goals. We conclude that global health policy leaders and stakeholders should procure and maintain appropriate global vaccine rotating stocks for measles and rubella vaccine now to support current regional elimination goals, and should probably also do so for other vaccines to help prevent and control endemic or epidemic diseases. This work suggests the need to better model global vaccine supplies to improve efficiency in the vaccine supply chain, ensure adequate supplies to support elimination and eradication initiatives, and support progress toward the goals of the Global Vaccine Action Plan.
Collapse
Affiliation(s)
- Kimberly M Thompson
- Kid Risk, Inc, 10524 Moss Park Rd., Ste. 204-364, Orlando, FL, USA
- University of Central Florida, College of Medicine, Orlando, FL, USA
| | | |
Collapse
|
22
|
Duintjer Tebbens RJ, Thompson KM. Managing the risk of circulating vaccine-derived poliovirus during the endgame: oral poliovirus vaccine needs. BMC Infect Dis 2015; 15:390. [PMID: 26404780 PMCID: PMC4582727 DOI: 10.1186/s12879-015-1114-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/07/2015] [Indexed: 12/17/2022] Open
Abstract
Background The Global Polio Eradication Initiative plans for coordinated cessation of oral poliovirus vaccine (OPV) use, beginning with serotype 2-containing OPV (i.e., OPV2 cessation) followed by the remaining two OPV serotypes (i.e., OPV13 cessation). The risk of circulating vaccine-derived poliovirus (cVDPV) outbreaks after OPV cessation of any serotype depends on the serotype-specific population immunity to transmission prior to its cessation. Methods Based on an existing integrated global model of poliovirus risk management policies, we estimate the serotype-specific OPV doses required to manage population immunity for a strategy of intensive supplemental immunization activities (SIAs) shortly before OPV cessation of each serotype. The strategy seeks to prevent any cVDPV outbreaks after OPV cessation, although actual events remain stochastic. Results Managing the risks of OPV cessation of any serotype depends on achieving sufficient population immunity to transmission to transmission at OPV cessation. This will require that countries with sub-optimal routine immunization coverage and/or conditions that favor poliovirus transmission conduct SIAs with homotypic OPV shortly before its planned coordinated cessation. The model suggests the need to increase trivalent OPV use in SIAs by approximately 40 % or more during the year before OPV2 cessation and to continue bOPV SIAs between the time of OPV2 cessation and OPV13 cessation. Conclusions Managing the risks of cVDPVs in the polio endgame will require serotype-specific OPV SIAs in some areas prior to OPV cessation and lead to demands for additional doses of the vaccine in the short term that will affect managers and manufacturers.
Collapse
|
23
|
Duintjer Tebbens RJ, Thompson KM. Managing the risk of circulating vaccine-derived poliovirus during the endgame: oral poliovirus vaccine needs. BMC Infect Dis 2015. [PMID: 26404780 DOI: 10.1186/s12879-12015-11114-12876] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
BACKGROUND The Global Polio Eradication Initiative plans for coordinated cessation of oral poliovirus vaccine (OPV) use, beginning with serotype 2-containing OPV (i.e., OPV2 cessation) followed by the remaining two OPV serotypes (i.e., OPV13 cessation). The risk of circulating vaccine-derived poliovirus (cVDPV) outbreaks after OPV cessation of any serotype depends on the serotype-specific population immunity to transmission prior to its cessation. METHODS Based on an existing integrated global model of poliovirus risk management policies, we estimate the serotype-specific OPV doses required to manage population immunity for a strategy of intensive supplemental immunization activities (SIAs) shortly before OPV cessation of each serotype. The strategy seeks to prevent any cVDPV outbreaks after OPV cessation, although actual events remain stochastic. RESULTS Managing the risks of OPV cessation of any serotype depends on achieving sufficient population immunity to transmission to transmission at OPV cessation. This will require that countries with sub-optimal routine immunization coverage and/or conditions that favor poliovirus transmission conduct SIAs with homotypic OPV shortly before its planned coordinated cessation. The model suggests the need to increase trivalent OPV use in SIAs by approximately 40 % or more during the year before OPV2 cessation and to continue bOPV SIAs between the time of OPV2 cessation and OPV13 cessation. CONCLUSIONS Managing the risks of cVDPVs in the polio endgame will require serotype-specific OPV SIAs in some areas prior to OPV cessation and lead to demands for additional doses of the vaccine in the short term that will affect managers and manufacturers.
Collapse
|
24
|
Duintjer Tebbens RJ, Pallansch MA, Cochi SL, Wassilak SGF, Thompson KM. An economic analysis of poliovirus risk management policy options for 2013-2052. BMC Infect Dis 2015; 15:389. [PMID: 26404632 PMCID: PMC4582932 DOI: 10.1186/s12879-015-1112-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 09/07/2015] [Indexed: 01/05/2023] Open
Abstract
Background The Global Polio Eradication Initiative plans for coordinated cessation of oral poliovirus vaccine (OPV) after interrupting all wild poliovirus (WPV) transmission, but many questions remain related to long-term poliovirus risk management policies. Methods We used an integrated dynamic poliovirus transmission and stochastic risk model to simulate possible futures and estimate the health and economic outcomes of maintaining the 2013 status quo of continued OPV use in most developing countries compared with OPV cessation policies with various assumptions about global inactivated poliovirus vaccine (IPV) adoption. Results Continued OPV use after global WPV eradication leads to continued high costs and/or high cases. Global OPV cessation comes with a high probability of at least one outbreak, which aggressive outbreak response can successfully control in most instances. A low but non-zero probability exists of uncontrolled outbreaks following a poliovirus reintroduction long after OPV cessation in a population in which IPV-alone cannot prevent poliovirus transmission. We estimate global incremental net benefits during 2013–2052 of approximately $16 billion (US$2013) for OPV cessation with at least one IPV routine immunization dose in all countries until 2024 compared to continued OPV use, although significant uncertainty remains associated with the frequency of exportations between populations and the implementation of long term risk management policies. Conclusions Global OPV cessation offers the possibility of large future health and economic benefits compared to continued OPV use. Long-term poliovirus risk management interventions matter (e.g., IPV use duration, outbreak response, containment, continued surveillance, stockpile size and contents, vaccine production site requirements, potential antiviral drugs, and potential safer vaccines) and require careful consideration. Risk management activities can help to ensure a low risk of uncontrolled outbreaks and preserve or further increase the positive net benefits of OPV cessation. Important uncertainties will require more research, including characterizing immunodeficient long-term poliovirus excretor risks, containment risks, and the kinetics of outbreaks and response in an unprecedented world without widespread live poliovirus exposure. Electronic supplementary material The online version of this article (doi:10.1186/s12879-015-1112-8) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
| | - Mark A Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Stephen L Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Steven G F Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | | |
Collapse
|
25
|
Duintjer Tebbens RJ, Pallansch MA, Cochi SL, Wassilak SGF, Thompson KM. An economic analysis of poliovirus risk management policy options for 2013-2052. BMC Infect Dis 2015. [PMID: 26404632 DOI: 10.1186/s12879-12015-11112-12878] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023] Open
Abstract
BACKGROUND The Global Polio Eradication Initiative plans for coordinated cessation of oral poliovirus vaccine (OPV) after interrupting all wild poliovirus (WPV) transmission, but many questions remain related to long-term poliovirus risk management policies. METHODS We used an integrated dynamic poliovirus transmission and stochastic risk model to simulate possible futures and estimate the health and economic outcomes of maintaining the 2013 status quo of continued OPV use in most developing countries compared with OPV cessation policies with various assumptions about global inactivated poliovirus vaccine (IPV) adoption. RESULTS Continued OPV use after global WPV eradication leads to continued high costs and/or high cases. Global OPV cessation comes with a high probability of at least one outbreak, which aggressive outbreak response can successfully control in most instances. A low but non-zero probability exists of uncontrolled outbreaks following a poliovirus reintroduction long after OPV cessation in a population in which IPV-alone cannot prevent poliovirus transmission. We estimate global incremental net benefits during 2013-2052 of approximately $16 billion (US$2013) for OPV cessation with at least one IPV routine immunization dose in all countries until 2024 compared to continued OPV use, although significant uncertainty remains associated with the frequency of exportations between populations and the implementation of long term risk management policies. CONCLUSIONS Global OPV cessation offers the possibility of large future health and economic benefits compared to continued OPV use. Long-term poliovirus risk management interventions matter (e.g., IPV use duration, outbreak response, containment, continued surveillance, stockpile size and contents, vaccine production site requirements, potential antiviral drugs, and potential safer vaccines) and require careful consideration. Risk management activities can help to ensure a low risk of uncontrolled outbreaks and preserve or further increase the positive net benefits of OPV cessation. Important uncertainties will require more research, including characterizing immunodeficient long-term poliovirus excretor risks, containment risks, and the kinetics of outbreaks and response in an unprecedented world without widespread live poliovirus exposure.
Collapse
Affiliation(s)
| | - Mark A Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Stephen L Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Steven G F Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | | |
Collapse
|
26
|
Thompson KM, Duintjer Tebbens RJ. Health and economic consequences of different options for timing the coordinated global cessation of the three oral poliovirus vaccine serotypes. BMC Infect Dis 2015; 15:374. [PMID: 26381878 PMCID: PMC4574397 DOI: 10.1186/s12879-015-1113-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 09/07/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND World leaders remain committed to globally-coordinated oral poliovirus vaccine (OPV) cessation following successful eradication of wild polioviruses, but the best timing and strategy for implementation depend on existing and emerging conditions. METHODS Using an existing integrated global poliovirus risk management model, we explore alternatives to the current timing plan of coordinated cessation of each OPV serotype (i.e., OPV1, OPV2, and OPV3 cessation for serotypes 1, 2, and 3, respectively). We assume the current timing plan involves OPV2 cessation in 2016 followed by OPV1 and OPV3 cessation in 2019 and we compare this to alternative timing options, including cessation of all three serotypes in 2018 or 2019, and cessation of both OPV2 and OPV3 in 2017 followed by OPV1 in 2019. RESULTS If Supplemtal Immunization Activity frequency remains sufficiently high through cessation of the last OPV serotype, then all OPV cessation timing options prevent circulating vaccine-derived poliovirus (cVDPV) outbreaks after OPV cessation of any serotype. The various OPV cessation timing options result in relatively modest differences in expected vaccine-associated paralytic poliomyelitis cases and expected total of approximately 10-13 billion polio vaccine doses used. However, the expected amounts of vaccine of different OPV formulations needed changes dramatically with each OPV cessation timing option. Overall health economic impacts remain limited for timing options that only change the OPV formulation but preserve the currently planned year for cessation of the last OPV serotype and the global introduction of inactivated poliovirus vaccine (IPV) introduction. Earlier cessation of the last OPV serotype or later global IPV introduction yield approximately $1 billion in incremental net benefits due to saved vaccination costs, although the logistics of implementation of OPV cessation remain uncertain and challenging. CONCLUSIONS All countries should maintain the highest possible levels of population immunity to transmission for each poliovirus serotype prior to the coordinated cessation of the OPV serotype to manage cVDPV risks. If OPV2 cessation gets delayed, then global health leaders should consider other OPV cessation timing options.
Collapse
|
27
|
Thompson KM, Duintjer Tebbens RJ. The differential impact of oral poliovirus vaccine formulation choices on serotype-specific population immunity to poliovirus transmission. BMC Infect Dis 2015; 15:376. [PMID: 26382234 PMCID: PMC4574692 DOI: 10.1186/s12879-015-1116-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/07/2015] [Indexed: 11/22/2022] Open
Abstract
Background Prior analyses demonstrated the need for some countries and the Global Polio Eradication Initiative (GPEI) to conduct additional supplemental immunization activities (SIAs) with trivalent oral poliovirus vaccine (tOPV) prior to globally-coordinated cessation of all serotype 2-containing OPV (OPV2 cessation) to prevent the creation of serotype 2 circulating vaccine-derived poliovirus (cVDPV2) outbreaks after OPV2 cessation. The GPEI continues to focus on achieving and ensuring interruption of wild poliovirus serotype 1 (WPV1) and making vaccine choices that prioritize bivalent OPV (bOPV) for SIAs, nominally to increase population immunity to serotype 1, despite an aggressive timeline for OPV2 cessation. Methods We use an existing dynamic poliovirus transmission model of northwest Nigeria and an integrated global model for long-term poliovirus risk management to explore the impact of tOPV vs. bOPV vaccine choices on population immunity and cVDPV2 risks. Results Using tOPV instead of bOPV for SIAs leads to a minimal decrease in population immunity to transmission of serotypes 1 and 3 polioviruses, but a significantly higher population immunity to transmission of serotype 2 polioviruses. Failure to use tOPV in enough SIAs results in cVDPV2 emergence after OPV2 cessation in both the northwest Nigeria model and the global model. Despite perceptions to the contrary, prioritizing the use of bOPV over tOPV prior to OPV2 cessation does not significantly improve serotype 1 population immunity to transmission. Conclusions Immunization leaders need to focus on all three poliovirus serotypes to appropriately manage the risks of OPV cessation in the polio endgame. Focusing on population immunity to transmission to interrupt WPV1 transmission and manage pre-OPV cessation risks of cVDPVs, all countries performing poliovirus SIAs should use tOPV up until the time of OPV2 cessation, after which time they should continue to use the OPV vaccine formulation with all remaining serotypes until coordinated global cessation of those serotypes.
Collapse
|
28
|
Thompson KM, Duintjer Tebbens RJ. Health and economic consequences of different options for timing the coordinated global cessation of the three oral poliovirus vaccine serotypes. BMC Infect Dis 2015. [PMID: 26381878 DOI: 10.1186/s12879-12015-11113-12877] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
BACKGROUND World leaders remain committed to globally-coordinated oral poliovirus vaccine (OPV) cessation following successful eradication of wild polioviruses, but the best timing and strategy for implementation depend on existing and emerging conditions. METHODS Using an existing integrated global poliovirus risk management model, we explore alternatives to the current timing plan of coordinated cessation of each OPV serotype (i.e., OPV1, OPV2, and OPV3 cessation for serotypes 1, 2, and 3, respectively). We assume the current timing plan involves OPV2 cessation in 2016 followed by OPV1 and OPV3 cessation in 2019 and we compare this to alternative timing options, including cessation of all three serotypes in 2018 or 2019, and cessation of both OPV2 and OPV3 in 2017 followed by OPV1 in 2019. RESULTS If Supplemtal Immunization Activity frequency remains sufficiently high through cessation of the last OPV serotype, then all OPV cessation timing options prevent circulating vaccine-derived poliovirus (cVDPV) outbreaks after OPV cessation of any serotype. The various OPV cessation timing options result in relatively modest differences in expected vaccine-associated paralytic poliomyelitis cases and expected total of approximately 10-13 billion polio vaccine doses used. However, the expected amounts of vaccine of different OPV formulations needed changes dramatically with each OPV cessation timing option. Overall health economic impacts remain limited for timing options that only change the OPV formulation but preserve the currently planned year for cessation of the last OPV serotype and the global introduction of inactivated poliovirus vaccine (IPV) introduction. Earlier cessation of the last OPV serotype or later global IPV introduction yield approximately $1 billion in incremental net benefits due to saved vaccination costs, although the logistics of implementation of OPV cessation remain uncertain and challenging. CONCLUSIONS All countries should maintain the highest possible levels of population immunity to transmission for each poliovirus serotype prior to the coordinated cessation of the OPV serotype to manage cVDPV risks. If OPV2 cessation gets delayed, then global health leaders should consider other OPV cessation timing options.
Collapse
|
29
|
Thompson KM, Duintjer Tebbens RJ. The differential impact of oral poliovirus vaccine formulation choices on serotype-specific population immunity to poliovirus transmission. BMC Infect Dis 2015. [PMID: 26382234 DOI: 10.1186/s12879-12015-11116-12874] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
BACKGROUND Prior analyses demonstrated the need for some countries and the Global Polio Eradication Initiative (GPEI) to conduct additional supplemental immunization activities (SIAs) with trivalent oral poliovirus vaccine (tOPV) prior to globally-coordinated cessation of all serotype 2-containing OPV (OPV2 cessation) to prevent the creation of serotype 2 circulating vaccine-derived poliovirus (cVDPV2) outbreaks after OPV2 cessation. The GPEI continues to focus on achieving and ensuring interruption of wild poliovirus serotype 1 (WPV1) and making vaccine choices that prioritize bivalent OPV (bOPV) for SIAs, nominally to increase population immunity to serotype 1, despite an aggressive timeline for OPV2 cessation. METHODS We use an existing dynamic poliovirus transmission model of northwest Nigeria and an integrated global model for long-term poliovirus risk management to explore the impact of tOPV vs. bOPV vaccine choices on population immunity and cVDPV2 risks. RESULTS Using tOPV instead of bOPV for SIAs leads to a minimal decrease in population immunity to transmission of serotypes 1 and 3 polioviruses, but a significantly higher population immunity to transmission of serotype 2 polioviruses. Failure to use tOPV in enough SIAs results in cVDPV2 emergence after OPV2 cessation in both the northwest Nigeria model and the global model. Despite perceptions to the contrary, prioritizing the use of bOPV over tOPV prior to OPV2 cessation does not significantly improve serotype 1 population immunity to transmission. CONCLUSIONS Immunization leaders need to focus on all three poliovirus serotypes to appropriately manage the risks of OPV cessation in the polio endgame. Focusing on population immunity to transmission to interrupt WPV1 transmission and manage pre-OPV cessation risks of cVDPVs, all countries performing poliovirus SIAs should use tOPV up until the time of OPV2 cessation, after which time they should continue to use the OPV vaccine formulation with all remaining serotypes until coordinated global cessation of those serotypes.
Collapse
|
30
|
Thompson KM. Good news for billions of children who will receive IPV. THE LANCET. INFECTIOUS DISEASES 2015; 15:1120-1122. [PMID: 26289957 DOI: 10.1016/s1473-3099(15)00099-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 06/01/2015] [Indexed: 11/17/2022]
Affiliation(s)
- Kimberly M Thompson
- Kid Risk, Orlando, FL 32827, USA; UCF College of Medicine, Orlando, FL 32827, USA.
| |
Collapse
|
31
|
Duintjer Tebbens RJ, Pallansch MA, Wassilak SGF, Cochi SL, Thompson KM. Combinations of Quality and Frequency of Immunization Activities to Stop and Prevent Poliovirus Transmission in the High-Risk Area of Northwest Nigeria. PLoS One 2015; 10:e0130123. [PMID: 26068928 PMCID: PMC4465973 DOI: 10.1371/journal.pone.0130123] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 05/18/2015] [Indexed: 11/19/2022] Open
Abstract
Background Frequent supplemental immunization activities (SIAs) with the oral poliovirus vaccine (OPV) represent the primary strategy to interrupt poliovirus transmission in the last endemic areas. Materials and Methods Using a differential-equation based poliovirus transmission model tailored to high-risk areas in Nigeria, we perform one-way and multi-way sensitivity analyses to demonstrate the impact of different assumptions about routine immunization (RI) and the frequency and quality of SIAs on population immunity to transmission and persistence or emergence of circulating vaccine-derived polioviruses (cVDPVs) after OPV cessation. Results More trivalent OPV use remains critical to avoid serotype 2 cVDPVs. RI schedules with or without inactivated polio vaccine (IPV) could significantly improve population immunity if coverage increases well above current levels in under-vaccinated subpopulations. Similarly, the impact of SIAs on overall population immunity and cVDPV risks depends on their ability to reach under-vaccinated groups (i.e., SIA quality). Lower SIA coverage in the under-vaccinated subpopulation results in a higher frequency of SIAs needed to maintain high enough population immunity to avoid cVDPVs after OPV cessation. Conclusions National immunization program managers in northwest Nigeria should recognize the benefits of increasing RI and SIA quality. Sufficiently improving RI coverage and improving SIA quality will reduce the frequency of SIAs required to stop and prevent future poliovirus transmission. Better information about the incremental costs to identify and reach under-vaccinated children would help determine the optimal balance between spending to increase SIA and RI quality and spending to increase SIA frequency.
Collapse
Affiliation(s)
| | - Mark A. Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Steven G. F. Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Stephen L. Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | | |
Collapse
|
32
|
Kalkowska DA, Duintjer Tebbens RJ, Grotto I, Shulman LM, Anis E, Wassilak SGF, Pallansch MA, Thompson KM. Modeling options to manage type 1 wild poliovirus imported into Israel in 2013. J Infect Dis 2015; 211:1800-12. [PMID: 25505296 PMCID: PMC7887763 DOI: 10.1093/infdis/jiu674] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/02/2014] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND After 25 years without poliomyelitis cases caused by circulating wild poliovirus (WPV) in Israel, sewage sampling detected WPV type 1 (WPV1) in April 2013, despite high vaccination coverage with only inactivated poliovirus vaccine (IPV) since 2005. METHODS We used a differential equation-based model to simulate the dynamics of poliovirus transmission and population immunity in Israel due to past exposure to WPV and use of oral poliovirus vaccine (OPV) in addition to IPV. We explored the influences of various immunization options to stop imported WPV1 circulation in Israel. RESULTS We successfully modeled the potential for WPVs to circulate without detected cases in Israel. Maintaining a sequential IPV/OPV schedule instead of switching to an IPV-only schedule in 2005 would have kept population immunity high enough in Israel to prevent WPV1 circulation. The Israeli response to WPV1 detection prevented paralytic cases; a more rapid response might have interrupted transmission more quickly. CONCLUSIONS IPV-based protection alone might not provide sufficient population immunity to prevent poliovirus transmission after an importation. As countries transition to IPV in immunization schedules, they may need to actively manage population immunity and consider continued use of OPV, to avoid the potential circulation of imported live polioviruses before globally coordinated cessation of OPV use.
Collapse
Affiliation(s)
| | | | - Itamar Grotto
- Public Health Services Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva
| | - Lester M Shulman
- Public Health Services Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel
| | - Emilia Anis
- Division of Epidemiology, Ministry of Health, Jerusalem
| | | | - Mark A Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
| | | |
Collapse
|
33
|
Thompson KM, Kalkowska DA, Duintjer Tebbens RJ. Managing population immunity to reduce or eliminate the risks of circulation following the importation of polioviruses. Vaccine 2015; 33:1568-77. [PMID: 25701673 PMCID: PMC7907970 DOI: 10.1016/j.vaccine.2015.02.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 01/31/2015] [Accepted: 02/05/2015] [Indexed: 11/19/2022]
Abstract
Poliovirus importations into polio-free countries represent a major concern during the final phases of global eradication of wild polioviruses (WPVs). We extend dynamic transmission models to demonstrate the dynamics of population immunity out through 2020 for three countries that only used inactivated poliovirus vaccine (IPV) for routine immunization: the US, Israel, and The Netherlands. For each country, we explore the vulnerability to re-established transmission following an importation for each poliovirus serotype, including the impact of immunization choices following the serotype 1 WPV importation that occurred in 2013 in Israel. As population immunity declines below the threshold required to prevent transmission, countries become at risk for re-established transmission. Although importations represent stochastic events that countries cannot fully control because people cross borders and polioviruses mainly cause asymptomatic infections, countries can ensure that any importations die out. Our results suggest that the general US population will remain above the threshold for transmission through 2020. In contrast, Israel became vulnerable to re-established transmission of importations of live polioviruses by the late 2000s. In Israel, the recent WPV importation and outbreak response use of bivalent oral poliovirus vaccine (bOPV) eliminated the vulnerability to an importation of poliovirus serotypes 1 and 3 for several years, but not serotype 2. The Netherlands experienced a serotype 1 WPV outbreak in 1992-1993 and became vulnerable to re-established transmission in religious communities with low vaccine acceptance around the year 2000, although the general population remains well-protected from widespread transmission. All countries should invest in active management of population immunity to avoid the potential circulation of imported live polioviruses. IPV-using countries may wish to consider prevention opportunities and/or ensure preparedness for response. Countries currently using a sequential IPV/OPV schedule should continue to use all licensed OPV serotypes until global OPV cessation to minimize vulnerability to circulation of imported polioviruses.
Collapse
Affiliation(s)
- Kimberly M Thompson
- Kid Risk, Inc., Orlando, FL, USA; University of Central Florida, College of Medicine, Orlando, FL, USA.
| | - Dominika A Kalkowska
- Kid Risk, Inc., Orlando, FL, USA; Delft University of Technology, Delft, The Netherlands
| | | |
Collapse
|
34
|
Edens C, Dybdahl-Sissoko NC, Weldon WC, Oberste MS, Prausnitz MR. Inactivated polio vaccination using a microneedle patch is immunogenic in the rhesus macaque. Vaccine 2015; 33:4683-90. [PMID: 25749246 DOI: 10.1016/j.vaccine.2015.01.089] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 01/27/2015] [Accepted: 01/29/2015] [Indexed: 11/26/2022]
Abstract
The phased replacement of oral polio vaccine (OPV) with inactivated polio vaccine (IPV) is expected to significantly complicate mass vaccination campaigns, which are an important component of the global polio eradication endgame strategy. To simplify mass vaccination with IPV, we developed microneedle patches that are easy to administer, have a small package size, generate no sharps waste and are inexpensive to manufacture. When administered to rhesus macaques, neutralizing antibody titers were equivalent among monkeys vaccinated using microneedle patches and conventional intramuscular injection for IPV types 1 and 2. Serologic response to IPV type 3 vaccination was weaker after microneedle patch vaccination compared to intramuscular injection; however, we suspect the administered type 3 dose was lower due to a flawed pre-production IPV type 3 analytical method. IPV vaccination using microneedle patches was well tolerated by the monkeys. We conclude that IPV vaccination using a microneedle patch is immunogenic in rhesus macaques and may offer a simpler method of IPV vaccination of people to facilitate polio eradication.
Collapse
Affiliation(s)
- Chris Edens
- Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Naomi C Dybdahl-Sissoko
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - William C Weldon
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - M Steven Oberste
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | - Mark R Prausnitz
- Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Georgia Institute of Technology, Atlanta, GA 30332, USA; School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
| |
Collapse
|
35
|
Kalkowska DA, Duintjer Tebbens RJ, Pallansch MA, Cochi SL, Wassilak SGF, Thompson KM. Modeling undetected live poliovirus circulation after apparent interruption of transmission: implications for surveillance and vaccination. BMC Infect Dis 2015; 15:66. [PMID: 25886823 PMCID: PMC4344758 DOI: 10.1186/s12879-015-0791-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 01/30/2015] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Most poliovirus infections occur with no symptoms and this leads to the possibility of silent circulation, which complicates the confirmation of global goals to permanently end poliovirus transmission. Previous simple models based on hypothetical populations assumed perfect detection of symptomatic cases and suggested the need to observe no paralytic cases from wild polioviruses (WPVs) for approximately 3-4 years to achieve 95% confidence about eradication, but the complexities in real populations and the imperfect nature of surveillance require consideration. METHODS We revisit the probability of undetected poliovirus circulation using a more comprehensive model that reflects the conditions in a number of places with different characteristics related to WPV transmission, and we model the actual environmental WPV detection that occurred in Israel in 2013. We consider the analogous potential for undetected transmission of circulating vaccine-derived polioviruses. The model explicitly accounts for the impact of different vaccination activities before and after the last detected case of paralytic polio, different levels of surveillance, variability in transmissibility and neurovirulence among serotypes, and the possibility of asymptomatic participation in transmission by previously-vaccinated or infected individuals. RESULTS We find that prolonged circulation in the absence of cases and thus undetectable by case-based surveillance may occur if vaccination keeps population immunity close to but not over the threshold required for the interruption of transmission, as may occur in northwestern Nigeria for serotype 2 circulating vaccine-derived poliovirus in the event of insufficient tOPV use. Participation of IPV-vaccinated individuals in asymptomatic fecal-oral transmission may also contribute to extended transmission undetectable by case-based surveillance, as occurred in Israel. We also find that gaps or quality issues in surveillance could significantly reduce confidence about actual disruption. Maintaining high population immunity and high-quality surveillance for several years after the last detected polio cases will remain critical elements of the polio end game. CONCLUSIONS Countries will need to maintain vigilance in their surveillance for polioviruses and recognize that their risks of undetected circulation may differ as a function of their efforts to manage population immunity and to identify cases or circulating live polioviruses.
Collapse
Affiliation(s)
- Dominika A Kalkowska
- Kid Risk, Inc., 10524 Moss Park Road, Site 204-364, Orlando, FL, 32832, USA.
- Delft University of Technology, Delft, Netherlands.
| | | | - Mark A Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Stephen L Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Steven G F Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Kimberly M Thompson
- Kid Risk, Inc., 10524 Moss Park Road, Site 204-364, Orlando, FL, 32832, USA.
- College of Medicine, University of Central Florida, Orlando, FL, USA.
| |
Collapse
|
36
|
Kalkowska DA, Duintjer Tebbens RJ, Pallansch MA, Cochi SL, Wassilak SGF, Thompson KM. Modeling undetected live poliovirus circulation after apparent interruption of transmission: implications for surveillance and vaccination. BMC Infect Dis 2015. [PMID: 25886823 DOI: 10.1186/s12879-12015-10791-12875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023] Open
Abstract
BACKGROUND Most poliovirus infections occur with no symptoms and this leads to the possibility of silent circulation, which complicates the confirmation of global goals to permanently end poliovirus transmission. Previous simple models based on hypothetical populations assumed perfect detection of symptomatic cases and suggested the need to observe no paralytic cases from wild polioviruses (WPVs) for approximately 3-4 years to achieve 95% confidence about eradication, but the complexities in real populations and the imperfect nature of surveillance require consideration. METHODS We revisit the probability of undetected poliovirus circulation using a more comprehensive model that reflects the conditions in a number of places with different characteristics related to WPV transmission, and we model the actual environmental WPV detection that occurred in Israel in 2013. We consider the analogous potential for undetected transmission of circulating vaccine-derived polioviruses. The model explicitly accounts for the impact of different vaccination activities before and after the last detected case of paralytic polio, different levels of surveillance, variability in transmissibility and neurovirulence among serotypes, and the possibility of asymptomatic participation in transmission by previously-vaccinated or infected individuals. RESULTS We find that prolonged circulation in the absence of cases and thus undetectable by case-based surveillance may occur if vaccination keeps population immunity close to but not over the threshold required for the interruption of transmission, as may occur in northwestern Nigeria for serotype 2 circulating vaccine-derived poliovirus in the event of insufficient tOPV use. Participation of IPV-vaccinated individuals in asymptomatic fecal-oral transmission may also contribute to extended transmission undetectable by case-based surveillance, as occurred in Israel. We also find that gaps or quality issues in surveillance could significantly reduce confidence about actual disruption. Maintaining high population immunity and high-quality surveillance for several years after the last detected polio cases will remain critical elements of the polio end game. CONCLUSIONS Countries will need to maintain vigilance in their surveillance for polioviruses and recognize that their risks of undetected circulation may differ as a function of their efforts to manage population immunity and to identify cases or circulating live polioviruses.
Collapse
Affiliation(s)
- Dominika A Kalkowska
- Kid Risk, Inc., 10524 Moss Park Road, Site 204-364, Orlando, FL, 32832, USA.
- Delft University of Technology, Delft, Netherlands.
| | | | - Mark A Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Stephen L Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Steven G F Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Kimberly M Thompson
- Kid Risk, Inc., 10524 Moss Park Road, Site 204-364, Orlando, FL, 32832, USA.
- College of Medicine, University of Central Florida, Orlando, FL, USA.
| |
Collapse
|
37
|
Thompson KM, Duintjer Tebbens RJ. Modeling the dynamics of oral poliovirus vaccine cessation. J Infect Dis 2014; 210 Suppl 1:S475-84. [PMID: 25316870 DOI: 10.1093/infdis/jit845] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Oral poliovirus vaccine (OPV) results in an ongoing burden of poliomyelitis due to vaccine-associated paralytic poliomyelitis and circulating vaccine-derived polioviruses (cVDPVs). This motivates globally coordinated OPV cessation after wild poliovirus eradication. METHODS We modeled poliovirus transmission and OPV evolution to characterize the interaction between population immunity, OPV-related virus prevalence, and the emergence of cVDPVs after OPV cessation. We explored strategies to prevent and manage cVDPVs for countries that currently use OPV for immunization and characterized cVDPV emergence risks and OPV use for outbreak response. RESULTS Continued intense supplemental immunization activities until OPV cessation represent the best strategy to prevent cVDPV emergence after OPV cessation in areas with insufficient routine immunization coverage. Policy makers must actively manage population immunity before OPV cessation to prevent cVDPVs and aggressively respond if prevention fails. Sufficiently aggressive response with OPV to interrupt transmission of the cVDPV outbreak virus will lead to die-out of OPV-related viruses used for response in the outbreak population. Further analyses should consider the risk of exportation to other populations of the outbreak virus and any OPV used for outbreak response. CONCLUSIONS OPV cessation can successfully eliminate all circulating live polioviruses in a population. The polio end game requires active risk management.
Collapse
|
38
|
Kalkowska DA, Duintjer Tebbens RJ, Thompson KM. Modeling strategies to increase population immunity and prevent poliovirus transmission in 2 high-risk areas in northern India. J Infect Dis 2014; 210 Suppl 1:S398-411. [PMID: 25316861 DOI: 10.1093/infdis/jit844] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND India presented many challenges to the global effort to eliminate the transmission of wild polioviruses (WPVs) and poliomyelitis, with the last case of WPV type 2 in the world reported in northern India in 1999 and WPV types 1 and 3 circulating until early 2011. METHODS We used a differential equation-based model to characterize the dynamics of poliovirus transmission and various opportunities to increase and maintain high population immunity to poliovirus transmission for 2 high-risk areas in northern India. We explored options that India probably considered before 2011, to demonstrate the impact of strategies to accelerate WPV elimination and sustain high population immunity. We also characterized the impact of current and potential future vaccination strategies and explored the potential trade-offs associated with the various strategies. RESULTS National immunization policy choices impact population immunity, which leads to different numbers of expected paralytic cases and risks of circulating vaccine-derived poliovirus outbreaks. Assuming that India maintains high vaccination intensity everywhere, we do not anticipate issues with outbreaks of circulating vaccine-derived poliovirus type 2 infection following globally coordinated cessation of type 2-containting oral poliovirus vaccine use. We find a relatively modest potential role for inactivated poliovirus vaccine. CONCLUSIONS National policy makers should consider the impacts of their vaccine choices on population immunity to poliovirus transmission.
Collapse
Affiliation(s)
- Dominika A Kalkowska
- Kid Risk, Inc., Orlando, Florida Delft University of Technology, Delft, The Netherlands; and
| | | | - Kimberly M Thompson
- Kid Risk, Inc., Orlando, Florida College of Medicine, University of Central Florida, Orlando
| |
Collapse
|
39
|
Duintjer Tebbens RJ, Thompson KM. Modeling the potential role of inactivated poliovirus vaccine to manage the risks of oral poliovirus vaccine cessation. J Infect Dis 2014; 210 Suppl 1:S485-97. [PMID: 25316871 DOI: 10.1093/infdis/jit838] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The Global Polio Eradication Initiative plans to stop all oral poliovirus vaccine (OPV) after wild poliovirus eradication, starting with serotype 2. Stakeholders continue to discuss the role of using inactivated poliovirus vaccine (IPV) to manage the risks of circulating vaccine-derived polioviruses (cVDPVs) during the end game. METHODS We use a poliovirus transmission and OPV evolution model to explore the impact of various routine immunization policies involving IPV on population immunity dynamics and the probability and magnitude of cVDPV emergences following OPV cessation. RESULTS Adding a single IPV dose to an OPV-only routine immunization schedule at or just before OPV cessation produces very limited impact on the probability of cVDPV emergences and the number of expected polio cases in settings in which we expect cVDPVs in the absence of IPV use. The highest-cost option of switching to a 3-dose IPV schedule only marginally decreases cVDPV risks. Discontinuing supplemental immunization activities while introducing IPV prior to OPV cessation leads to an increase in cVDPV risks. CONCLUSIONS Introducing a dose of IPV in countries currently using OPV only for routine immunization offers protection from paralysis to successfully vaccinated recipients, but it does little to protect high-risk populations from cVDPV risks.
Collapse
|
40
|
Kalkowska DA, Duintjer Tebbens RJ, Thompson KM. Modeling strategies to increase population immunity and prevent poliovirus transmission in the high-risk area of northwest Nigeria. J Infect Dis 2014; 210 Suppl 1:S412-23. [PMID: 25316863 DOI: 10.1093/infdis/jit834] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Nigeria continues to struggle in its efforts to eliminate circulating live polioviruses using oral poliovirus vaccine (OPV). METHODS We modeled population immunity, and we estimated cases and the timing of transmission die-out for numerous policies that could accelerate the elimination of wild poliovirus type 1 (WPV1) and help Nigeria manage the risks of circulating vaccine-derived polioviruses (cVDPVs). We used a differential-equation based poliovirus transmission and OPV evolution model focused on northwest Nigeria to characterize the impact and trade-offs of potential vaccination strategies, including the introduction of inactivated poliovirus vaccine (IPV). RESULTS Northwest Nigeria appears close to reaching the threshold of population immunity it must exceed to stop WPV1 transmission if it continues immunizing previously under-vaccinated children. Avoiding type 2 cVDPVs (cVDPV2s) will depend on using sufficient amounts of trivalent OPV, which will also reduce the risks of cVDPV2s after coordinated cessation of type 2-containing OPV (OPV2). Using IPV during the OPV cessation period may increase population immunity, but it leads to a much lower impact on cVDPV risks than ensuring sufficient trivalent OPV use prior to OPV2 cessation. CONCLUSIONS Northwest Nigeria needs to intensify and sustain its immunization efforts to achieve and maintain higher levels of population immunity.
Collapse
Affiliation(s)
- Dominika A Kalkowska
- Kid Risk, Inc, Orlando, Florida Delft University of Technology, Delft, The Netherlands
| | | | | |
Collapse
|
41
|
Kisjes KH, Duintjer Tebbens RJ, Wallace GS, Pallansch MA, Cochi SL, Wassilak SGF, Thompson KM. Individual-based modeling of potential poliovirus transmission in connected religious communities in North America with low uptake of vaccination. J Infect Dis 2014; 210 Suppl 1:S424-33. [PMID: 25316864 DOI: 10.1093/infdis/jit843] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Pockets of undervaccinated individuals continue to raise concerns about their potential to sustain epidemic transmission of vaccine-preventable diseases. Prior importations of live polioviruses (LPVs) into Amish communities in North America led to their recognition as a potential and identifiable linked network of undervaccinated individuals. METHODS We developed an individual-based model to explore the potential transmission of a LPV throughout the North American Amish population. RESULTS Our model demonstrates the expected limited impact associated with the historical importations, which occurred in isolated communities during the low season for poliovirus transmission. We show that some conditions could potentially lead to wider circulation of LPVs and cases of paralytic polio in Amish communities if an importation occurred during or after 2013. The impact will depend on the uncertain historical immunity to poliovirus infection among members of the community. CONCLUSIONS Heterogeneity in immunization coverage represents a risk factor for potential outbreaks of polio if introduction of a LPV occurs, although overall high population immunity in North America suggests that transmission would remain relatively limited. Efforts to prevent spread between Amish church districts with any feasible measures may offer the best opportunity to contain an outbreak and limit its size.
Collapse
Affiliation(s)
- Kasper H Kisjes
- Kid Risk, Inc. Delft University of Technology, Delft, The Netherlands
| | | | - Gregory S Wallace
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention
| | - Mark A Pallansch
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention
| | - Stephen L Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Steven G F Wassilak
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Kimberly M Thompson
- Kid Risk, Inc. College of Medicine, University of Central Florida, Orlando, Florida
| |
Collapse
|
42
|
Affiliation(s)
- Kimberly M Thompson
- Preventive Medicine and Global Health, University of Central Florida, College of Medicine, Orlando, FL 32827, USA.
| |
Collapse
|
43
|
Duintjer Tebbens RJ, Kalkowska DA, Wassilak SGF, Pallansch MA, Cochi SL, Thompson KM. The potential impact of expanding target age groups for polio immunization campaigns. BMC Infect Dis 2014; 14:45. [PMID: 24472313 PMCID: PMC3918103 DOI: 10.1186/1471-2334-14-45] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/20/2014] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Global efforts to eradicate wild polioviruses (WPVs) continue to face challenges due to uninterrupted endemic WPV transmission in three countries and importation-related outbreaks into previously polio-free countries. We explore the potential role of including older children and adults in supplemental immunization activities (SIAs) to more rapidly increase population immunity and prevent or stop transmission. METHODS We use a differential equation-based dynamic poliovirus transmission model to analyze the epidemiological impact and vaccine resource implications of expanding target age groups in SIAs. We explore the use of older age groups in SIAs for three situations: alternative responses to the 2010 outbreak in Tajikistan, retrospective examination of elimination in two high-risk states in northern India, and prospective and retrospective strategies to accelerate elimination in endemic northwestern Nigeria. Our model recognizes the ability of individuals with waned mucosal immunity (i.e., immunity from a historical live poliovirus infection) to become re-infected and contribute to transmission to a limited extent. RESULTS SIAs involving expanded age groups reduce overall caseloads, decrease transmission, and generally lead to a small reduction in the time to achieve WPV elimination. Analysis of preventive expanded age group SIAs in Tajikistan or prior to type-specific surges in incidence in high-risk areas of India and Nigeria showed the greatest potential benefits of expanded age groups. Analysis of expanded age group SIAs in outbreak situations or to accelerate the interruption of endemic transmission showed relatively less benefit, largely due to the circulation of WPV reaching individuals sooner or more effectively than the SIAs. The India and Nigeria results depend strongly on how well SIAs involving expanded age groups reach relatively isolated subpopulations that sustain clusters of susceptible children, which we assume play a key role in persistent endemic WPV transmission in these areas. CONCLUSIONS This study suggests the need to carefully consider the epidemiological situation in the context of decisions to use expanded age group SIAs. Subpopulations of susceptible individuals may independently sustain transmission, which will reduce the overall benefits associated with using expanded age group SIAs to increase population immunity to a sufficiently high level to stop transmission and reduce the incidence of paralytic cases.
Collapse
|
44
|
Thompson KM, Duintjer Tebbens RJ. National choices related to inactivated poliovirus vaccine, innovation and the endgame of global polio eradication. Expert Rev Vaccines 2013; 13:221-34. [PMID: 24308581 DOI: 10.1586/14760584.2014.864563] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Achieving the goal of a world free of poliomyelitis still requires significant effort. Although polio immunization represents a mature area, the polio endgame will require new tools and strategies, particularly as national and global health leaders coordinate the cessation of all three serotypes of oral poliovirus vaccine and increasingly adopt inactivated poliovirus vaccine (IPV). Poliovirus epidemiology and the global options for managing polioviruses continue to evolve, along with our understanding and appreciation of the resources needed and the risks that require management. Based on insights from modeling, we offer some perspective on the current status of plans and opportunities to achieve and maintain a world free of wild polioviruses and to successfully implement oral poliovirus vaccine cessation. IPV costs and potential wastage will represent an important consideration for national policy makers. Innovations may reduce future IPV costs, but the world urgently needs lower-cost IPV options.
Collapse
|
45
|
Duintjer Tebbens RJ, Pallansch MA, Chumakov KM, Halsey NA, Hovi T, Minor PD, Modlin JF, Patriarca PA, Sutter RW, Wright PF, Wassilak SGF, Cochi SL, Kim JH, Thompson KM. Review and assessment of poliovirus immunity and transmission: synthesis of knowledge gaps and identification of research needs. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2013; 33:606-46. [PMID: 23550968 PMCID: PMC7890644 DOI: 10.1111/risa.12031] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
With the intensifying global efforts to eradicate wild polioviruses, policymakers face complex decisions related to achieving eradication and managing posteradication risks. These decisions and the expanding use of inactivated poliovirus vaccine (IPV) trigger renewed interest in poliovirus immunity, particularly the role of mucosal immunity in the transmission of polioviruses. Sustained high population immunity to poliovirus transmission represents a key prerequisite to eradication, but poliovirus immunity and transmission remain poorly understood despite decades of studies. In April 2010, the U.S. Centers for Disease Control and Prevention convened an international group of experts on poliovirus immunology and virology to review the literature relevant for modeling poliovirus transmission, develop a consensus about related uncertainties, and identify research needs. This article synthesizes the quantitative assessments and research needs identified during the process. Limitations in the evidence from oral poliovirus vaccine (OPV) challenge studies and other relevant data led to differences in expert assessments, indicating the need for additional data, particularly in several priority areas for research: (1) the ability of IPV-induced immunity to prevent or reduce excretion and affect transmission, (2) the impact of waning immunity on the probability and extent of poliovirus excretion, (3) the relationship between the concentration of poliovirus excreted and infectiousness to others in different settings, and (4) the relative role of fecal-oral versus oropharyngeal transmission. This assessment of current knowledge supports the immediate conduct of additional studies to address the gaps.
Collapse
|
46
|
Duintjer Tebbens RJ, Pallansch MA, Chumakov KM, Halsey NA, Hovi T, Minor PD, Modlin JF, Patriarca PA, Sutter RW, Wright PF, Wassilak SGF, Cochi SL, Kim JH, Thompson KM. Expert review on poliovirus immunity and transmission. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2013; 33:544-605. [PMID: 22804479 PMCID: PMC7896540 DOI: 10.1111/j.1539-6924.2012.01864.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Successfully managing risks to achieve wild polioviruses (WPVs) eradication and address the complexities of oral poliovirus vaccine (OPV) cessation to stop all cases of paralytic poliomyelitis depends strongly on our collective understanding of poliovirus immunity and transmission. With increased shifting from OPV to inactivated poliovirus vaccine (IPV), numerous risk management choices motivate the need to understand the tradeoffs and uncertainties and to develop models to help inform decisions. The U.S. Centers for Disease Control and Prevention hosted a meeting of international experts in April 2010 to review the available literature relevant to poliovirus immunity and transmission. This expert review evaluates 66 OPV challenge studies and other evidence to support the development of quantitative models of poliovirus transmission and potential outbreaks. This review focuses on characterization of immunity as a function of exposure history in terms of susceptibility to excretion, duration of excretion, and concentration of excreted virus. We also discuss the evidence of waning of host immunity to poliovirus transmission, the relationship between the concentration of poliovirus excreted and infectiousness, the importance of different transmission routes, and the differences in transmissibility between OPV and WPV. We discuss the limitations of the available evidence for use in polio risk models, and conclude that despite the relatively large number of studies on immunity, very limited data exist to directly support quantification of model inputs related to transmission. Given the limitations in the evidence, we identify the need for expert input to derive quantitative model inputs from the existing data.
Collapse
|
47
|
Duintjer Tebbens RJ, Pallansch MA, Kalkowska DA, Wassilak SGF, Cochi SL, Thompson KM. Characterizing poliovirus transmission and evolution: insights from modeling experiences with wild and vaccine-related polioviruses. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2013; 33:703-749. [PMID: 23521018 DOI: 10.1111/risa.12044] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
With national and global health policymakers facing numerous complex decisions related to achieving and maintaining polio eradication, we expanded our previously developed dynamic poliovirus transmission model using information from an expert literature review process and including additional immunity states and the evolution of oral poliovirus vaccine (OPV). The model explicitly considers serotype differences and distinguishes fecal-oral and oropharyngeal transmission. We evaluated the model by simulating diverse historical experiences with polioviruses, including one country that eliminated wild poliovirus using both OPV and inactivated poliovirus vaccine (IPV) (USA), three importation outbreaks of wild poliovirus (Albania, the Netherlands, Tajikistan), one situation in which no circulating vaccine-derived polioviruses (cVDPVs) emerge despite annual OPV use and cessation (Cuba), three cVDPV outbreaks (Haiti, Madura Island in Indonesia, northern Nigeria), one area of current endemic circulation of all three serotypes (northern Nigeria), and one area with recent endemic circulation and subsequent elimination of multiple serotypes (northern India). We find that when sufficient information about the conditions exists, the model can reproduce the general behavior of poliovirus transmission and outbreaks while maintaining consistency in the generic model inputs. The assumption of spatially homogeneous mixing remains a significant limitation that affects the performance of the differential equation-based model when significant heterogeneities in immunity and mixing may exist. Further studies on OPV virus evolution and improved understanding of the mechanisms of mixing and transmission may help to better characterize poliovirus transmission in populations. Broad application of the model promises to offer insights in the context of global and national policy and economic models.
Collapse
|
48
|
Lowther SA, Roesel S, O'Connor P, Landaverde M, Oblapenko G, Deshevoi S, Ajay G, Buff A, Safwat H, Salla M, Tangermann R, Khetsuriani N, Martin R, Wassilak S. World Health Organization regional assessments of the risks of poliovirus outbreaks. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2013; 33:664-79. [PMID: 23520991 DOI: 10.1111/risa.12032] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
While global polio eradication requires tremendous efforts in countries where wild polioviruses (WPVs) circulate, numerous outbreaks have occurred following WPV importation into previously polio-free countries. Countries that have interrupted endemic WPV transmission should continue to conduct routine risk assessments and implement mitigation activities to maintain their polio-free status as long as wild poliovirus circulates anywhere in the world. This article reviews the methods used by World Health Organization (WHO) regional offices to qualitatively assess risk of WPV outbreaks following an importation. We describe the strengths and weaknesses of various risk assessment approaches, and opportunities to harmonize approaches. These qualitative assessments broadly categorize risk as high, medium, or low using available national information related to susceptibility, the ability to rapidly detect WPV, and other population or program factors that influence transmission, which the regions characterize using polio vaccination coverage, surveillance data, and other indicators (e.g., sanitation), respectively. Data quality and adequacy represent a challenge in all regions. WHO regions differ with respect to the methods, processes, cut-off values, and weighting used, which limits comparisons of risk assessment results among regions. Ongoing evaluation of indicators within regions and further harmonization of methods between regions are needed to effectively plan risk mitigation activities in a setting of finite resources for funding and continued WPV circulation.
Collapse
Affiliation(s)
- Sara A Lowther
- Centers for Disease Control and Prevention (CDC), Center for Global Health, Global Immunization Division, Atlanta, Georgia, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Thompson KM. Modeling poliovirus risks and the legacy of polio eradication. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2013; 33:505-15. [PMID: 23550939 PMCID: PMC7896538 DOI: 10.1111/risa.12030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This introduction to the special issue on modeling poliovirus risks provides context about historical efforts to manage polioviruses and reviews the insights from models developed to support risk management and policy development. Following an overview of the contents of the special issue, the introduction explores the road ahead and offers perspective on the legacy of polio eradication.
Collapse
|
50
|
Thompson KM, Pallansch MA, Tebbens RJD, Wassilak SG, Cochi SL. Modeling population immunity to support efforts to end the transmission of live polioviruses. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2013; 33:647-63. [PMID: 22985171 PMCID: PMC7896539 DOI: 10.1111/j.1539-6924.2012.01891.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Eradication of wild poliovirus (WPV) types 1 and 3, prevention and cessation of circulating vaccine-derived polioviruses, and achievement and maintenance of a world free of paralytic polio cases requires active risk management by focusing on population immunity and coordinated cessation of oral poliovirus vaccine (OPV). We suggest the need for a complementary and different conceptual approach to achieve eradication compared to the current case-based approach using surveillance for acute flaccid paralysis (AFP) to identify symptomatic poliovirus infections. Specifically, we describe a modeling approach to characterize overall population immunity to poliovirus transmission. The approach deals with the realities that exposure to live polioviruses (e.g., WPV, OPV) and/or vaccination with inactivated poliovirus vaccine provides protection from paralytic polio (i.e., disease), but does not eliminate the potential for reinfection or asymptomatic participation in poliovirus transmission, which may increase with time because of waning immunity. The AFP surveillance system provides evidence of symptomatic poliovirus infections detected, which indicate immunity gaps after outbreaks occur, and this system represents an appropriate focus for controlling disease outbreaks. We describe a conceptual dynamic model to characterize population immunity to poliovirus transmission that helps identify risks created by immunity gaps before outbreaks occur, which provides an opportunity for national and global policymakers to manage the risk of poliovirus and prevent outbreaks before they occur. We suggest that dynamically modeling risk represents an essential tool as the number of cases approaches zero.
Collapse
|