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Iqbal MS, Shahzad M, Ahmed N, Akgül A, Ghafoor M, Hassani MK. Optimum study of fractional polio model with exponential decay kernel. Sci Rep 2024; 14:17237. [PMID: 39060276 PMCID: PMC11282190 DOI: 10.1038/s41598-024-64611-6] [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: 01/02/2024] [Accepted: 06/11/2024] [Indexed: 07/28/2024] Open
Abstract
This study introduces a fractional order model to investigate the dynamics of polio disease spread, focusing on its significance, unique results, and conclusions. We emphasize the importance of understanding polio transmission dynamics and propose a novel approach using a fractional order model with an exponential decay kernel. Through rigorous analysis, including existence and stability assessment applying the Caputo Fabrizio fractional operator, we derive key insights into the disease dynamics. Our findings reveal distinct disease-free equilibrium (DFE) and endemic equilibrium (EE) points, shedding light on the disease's stability. Furthermore, graphical representations and numerical simulations demonstrate the behavior of the disease under various parameter values, enhancing our understanding of polio transmission dynamics. In conclusion, this study offers valuable insights into the spread of polio and contributes to the broader understanding of infectious disease dynamics.
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Affiliation(s)
- Muhammad Sajid Iqbal
- School of Foundation Studies and Mathematics, OUC with Liverpool John Moores University (UK), Qatar Campus, 12253, Doha, Qatar
- Department of Humanities & Basic Science, Military College of Signals, NUST, Islamabad, Pakistan
- MEU Research Unit, Faculty of Information Technology, Middle East University, Amman, 11831, Jordan
| | - Muhammad Shahzad
- Department of Mathematics and statistics, The University of Lahore, Lahore, Pakistan
| | - Nauman Ahmed
- Department of Mathematics and statistics, The University of Lahore, Lahore, Pakistan.
- Department of Computer Science and Mathematics, Lebanese American University, Beirut, Lebanon.
| | - Ali Akgül
- Department of Mathematics, Art and Science Faculty, Siirt University, 56100, Siirt, Turkey.
- Department of Computer Science and Mathematics, Lebanese American University, Beirut, Lebanon.
| | - Madiha Ghafoor
- Department of Mathematics and statistics, The University of Lahore, Lahore, Pakistan
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Thompson KM, Badizadegan K. Review of Poliovirus Transmission and Economic Modeling to Support Global Polio Eradication: 2020-2024. Pathogens 2024; 13:435. [PMID: 38921733 PMCID: PMC11206708 DOI: 10.3390/pathogens13060435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 05/16/2024] [Accepted: 05/18/2024] [Indexed: 06/27/2024] Open
Abstract
Continued investment in the development and application of mathematical models of poliovirus transmission, economics, and risks leads to their use in support of polio endgame strategy development and risk management policies. This study complements an earlier review covering the period 2000-2019 and discusses the evolution of studies published since 2020 by modeling groups supported by the Global Polio Eradication Initiative (GPEI) partners and others. We systematically review modeling papers published in English in peer-reviewed journals from 2020-2024.25 that focus on poliovirus transmission and health economic analyses. In spite of the long-anticipated end of poliovirus transmission and the GPEI sunset, which would lead to the end of its support for modeling, we find that the number of modeling groups supported by GPEI partners doubled and the rate of their publications increased. Modeling continued to play a role in supporting GPEI and national/regional policies, but changes in polio eradication governance, decentralized management and decision-making, and increased heterogeneity in modeling approaches and findings decreased the overall impact of modeling results. Meanwhile, the failure of the 2016 globally coordinated cessation of type 2 oral poliovirus vaccine use for preventive immunization and the introduction of new poliovirus vaccines and formulation, increased the complexity and uncertainty of poliovirus transmission and economic models and policy recommendations during this time.
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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.
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Badizadegan K, Kalkowska DA, Thompson KM. Health Economic Analysis of Antiviral Drugs in the Global Polio Eradication Endgame. Med Decis Making 2023; 43:850-862. [PMID: 37577803 PMCID: PMC10680042 DOI: 10.1177/0272989x231191127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
BACKGROUND Polio antiviral drugs (PAVDs) may provide a critical tool in the eradication endgame by stopping poliovirus infections in immunodeficient individuals who may not clear the virus without therapeutic intervention. Although prolonged/chronic poliovirus excreters are rare, they represent a source of poliovirus reintroduction into the general population. Prior studies that assumed the successful cessation of all oral poliovirus vaccine (OPV) use estimated the potential upper bound of the incremental net benefits (INBs) of resource investments in research and development of PAVDs. However, delays in polio eradication, OPV cessation, and the development of PAVDs necessitate an updated economic analysis to reevaluate the costs and benefits of further investments in PAVDs. METHODS Using a global integrated model of polio transmission, immunity, vaccine dynamics, risks, and economics, we explore the risks of reintroduction of polio transmission due to immunodeficiency-related vaccine-derived poliovirus (iVDPV) excreters and reevaluate the upper bound of the INBs of PAVDs. RESULTS Under the current conditions, for which the use of OPV will likely continue for the foreseeable future, even with successful eradication of type 1 wild poliovirus by the end of 2023 and continued use of Sabin OPV for outbreak response, we estimate an upper bound INB of 60 million US$2019. With >100 million US$2019 already invested in PAVD development and with the introduction of novel OPVs that are less likely to revert to neurovirulence, our analysis suggests the expected INBs of PAVDs would not offset their costs. CONCLUSIONS While PAVDs could play an important role in the polio endgame, their expected economic benefits drop with ongoing OPV use and poliovirus transmissions. However, stakeholders may pursue the development of PAVDs as a desired product regardless of their economic benefits.HighlightsWhile polio antiviral drugs could play an important role in the polio endgame, their expected economic benefits continue to drop with delays in polio eradication and the continued use of oral poliovirus vaccines.The incremental net benefits of investments in polio antiviral drug development and screening for immunodeficiency-related circulating polioviruses are small.Limited global resources are better spent on increasing global population immunity to polioviruses to stop and prevent poliovirus transmission.
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Watson C. Can the world really stop wild polio by the end of 2023? Nature 2023; 620:706-707. [PMID: 37582941 DOI: 10.1038/d41586-023-02577-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2023]
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Kaba D, Koffi M, Kouakou L, N’Gouan EK, Djohan V, Courtin F, N’Djetchi MK, Coulibaly B, Adingra GP, Berté D, Ta BTD, Koné M, Traoré BM, Sutherland SA, Crump RE, Huang CI, Madan J, Bessell PR, Barreaux A, Solano P, Crowley EH, Rock KS, Jamonneau V. Towards the sustainable elimination of gambiense human African trypanosomiasis in Côte d'Ivoire using an integrated approach. PLoS Negl Trop Dis 2023; 17:e0011514. [PMID: 37523361 PMCID: PMC10443840 DOI: 10.1371/journal.pntd.0011514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 08/22/2023] [Accepted: 07/07/2023] [Indexed: 08/02/2023] Open
Abstract
BACKGROUND Human African trypanosomiasis is a parasitic disease caused by trypanosomes among which Trypanosoma brucei gambiense is responsible for a chronic form (gHAT) in West and Central Africa. Its elimination as a public health problem (EPHP) was targeted for 2020. Côte d'Ivoire was one of the first countries to be validated by WHO in 2020 and this was particularly challenging as the country still reported around a hundred cases a year in the early 2000s. This article describes the strategies implemented including a mathematical model to evaluate the reporting results and infer progress towards sustainable elimination. METHODS The control methods used combined both exhaustive and targeted medical screening strategies including the follow-up of seropositive subjects- considered as potential asymptomatic carriers to diagnose and treat cases- as well as vector control to reduce the risk of transmission in the most at-risk areas. A mechanistic model was used to estimate the number of underlying infections and the probability of elimination of transmission (EoT) was met between 2000-2021 in two endemic and two hypo-endemic health districts. RESULTS Between 2015 and 2019, nine gHAT cases were detected in the two endemic health districts of Bouaflé and Sinfra in which the number of cases/10,000 inhabitants was far below 1, a necessary condition for validating EPHP. Modelling estimated a slow but steady decline in transmission across the health districts, bolstered in the two endemic health districts by the introduction of vector control. The decrease in underlying transmission in all health districts corresponds to a high probability that EoT has already occurred in Côte d'Ivoire. CONCLUSION This success was achieved through a multi-stakeholder and multidisciplinary one health approach where research has played a major role in adapting tools and strategies to this large epidemiological transition to a very low prevalence. This integrated approach will need to continue to reach the verification of EoT in Côte d'Ivoire targeted by 2025.
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Affiliation(s)
- Dramane Kaba
- Unité de Recherche « Trypanosomoses », Institut Pierre Richet, Bouaké, Côte d’Ivoire
| | - Mathurin Koffi
- Laboratoire de Biodiversité et Gestion des Ecosystèmes Tropicaux, Unité de Recherche en Génétique et Epidémiologie Moléculaire, UFR Environnement, Université Jean Lorougnon Guédé, Daloa, Côte d’Ivoire
| | - Lingué Kouakou
- Programme National d’Élimination de la Trypanosomiase Humaine Africaine, Abidjan, Côte d’Ivoire
| | | | - Vincent Djohan
- Unité de Recherche « Trypanosomoses », Institut Pierre Richet, Bouaké, Côte d’Ivoire
| | - Fabrice Courtin
- Unité Mixte de Recherche IRD-CIRAD 177, INTERTRYP, Institut de Recherche pour le Développement, Université de Montpellier, Montpellier, France
| | - Martial Kassi N’Djetchi
- Laboratoire de Biodiversité et Gestion des Ecosystèmes Tropicaux, Unité de Recherche en Génétique et Epidémiologie Moléculaire, UFR Environnement, Université Jean Lorougnon Guédé, Daloa, Côte d’Ivoire
| | - Bamoro Coulibaly
- Unité de Recherche « Trypanosomoses », Institut Pierre Richet, Bouaké, Côte d’Ivoire
| | - Guy Pacôme Adingra
- Unité de Recherche « Trypanosomoses », Institut Pierre Richet, Bouaké, Côte d’Ivoire
| | - Djakaridja Berté
- Unité de Recherche « Trypanosomoses », Institut Pierre Richet, Bouaké, Côte d’Ivoire
| | - Bi Tra Dieudonné Ta
- Unité de Recherche « Trypanosomoses », Institut Pierre Richet, Bouaké, Côte d’Ivoire
| | - Minayégninrin Koné
- Unité de Recherche « Trypanosomoses », Institut Pierre Richet, Bouaké, Côte d’Ivoire
- Laboratoire de Biodiversité et Gestion des Ecosystèmes Tropicaux, Unité de Recherche en Génétique et Epidémiologie Moléculaire, UFR Environnement, Université Jean Lorougnon Guédé, Daloa, Côte d’Ivoire
| | - Barkissa Mélika Traoré
- Laboratoire de Biodiversité et Gestion des Ecosystèmes Tropicaux, Unité de Recherche en Génétique et Epidémiologie Moléculaire, UFR Environnement, Université Jean Lorougnon Guédé, Daloa, Côte d’Ivoire
| | - Samuel A. Sutherland
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematical Sciences Building, The University of Warwick, Coventry, United Kingdom
- Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Ronald E. Crump
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematical Sciences Building, The University of Warwick, Coventry, United Kingdom
- Mathematics Institute, Zeeman Building, The University of Warwick, Coventry, United Kingdom
| | - Ching-I Huang
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematical Sciences Building, The University of Warwick, Coventry, United Kingdom
- Mathematics Institute, Zeeman Building, The University of Warwick, Coventry, United Kingdom
| | - Jason Madan
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematical Sciences Building, The University of Warwick, Coventry, United Kingdom
- Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | | | - Antoine Barreaux
- Unité Mixte de Recherche IRD-CIRAD 177, INTERTRYP, Institut de Recherche pour le Développement, Université de Montpellier, Montpellier, France
| | - Philippe Solano
- Unité Mixte de Recherche IRD-CIRAD 177, INTERTRYP, Institut de Recherche pour le Développement, Université de Montpellier, Montpellier, France
| | - Emily H. Crowley
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematical Sciences Building, The University of Warwick, Coventry, United Kingdom
- Mathematics Institute, Zeeman Building, The University of Warwick, Coventry, United Kingdom
| | - Kat S. Rock
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematical Sciences Building, The University of Warwick, Coventry, United Kingdom
- Mathematics Institute, Zeeman Building, The University of Warwick, Coventry, United Kingdom
| | - Vincent Jamonneau
- Unité de Recherche « Trypanosomoses », Institut Pierre Richet, Bouaké, Côte d’Ivoire
- Unité Mixte de Recherche IRD-CIRAD 177, INTERTRYP, Institut de Recherche pour le Développement, Université de Montpellier, Montpellier, France
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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.
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Thompson KM, Kalkowska DA, Badizadegan K. Oral polio vaccine stockpile modeling: insights from recent experience. Expert Rev Vaccines 2023; 22:813-825. [PMID: 37747090 DOI: 10.1080/14760584.2023.2263096] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 09/21/2023] [Indexed: 09/26/2023]
Abstract
BACKGROUND Achieving polio eradication requires ensuring the delivery of sufficient supplies of the right vaccines to the right places at the right times. Despite large global markets, decades of use, and large quantity purchases of polio vaccines by national immunization programs and the Global Polio Eradication Initiative (GPEI), forecasting demand for the oral poliovirus vaccine (OPV) stockpile remains challenging. RESEARCH DESIGN AND METHODS We review OPV stockpile experience compared to pre-2016 expectations, actual demand, and changes in GPEI policies related to the procurement and use of type 2 OPV vaccines. We use available population and immunization schedule data to explore polio vaccine market segmentation, and its role in polio vaccine demand forecasting. RESULTS We find that substantial challenges remain in forecasting polio vaccine needs, mainly due to (1) deviations in implementation of plans that formed the basis for earlier forecasts, (2) lack of alignment of tactics/objectives among GPEI partners and other key stakeholders, (3) financing, and (4) uncertainty about development and licensure timelines for new polio vaccines and their field performance characteristics. CONCLUSIONS Mismatches between supply and demand over time have led to negative consequences associated with both oversupply and undersupply, as well as excess costs and potentially preventable cases.
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Thompson KM, Kalkowska DA, Badizadegan K. Health economic analysis of vaccine options for the polio eradication endgame: 2022-2036. Expert Rev Vaccines 2022; 21:1667-1674. [PMID: 36154436 PMCID: PMC10116513 DOI: 10.1080/14760584.2022.2128108] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND : Multiple vaccine options are available for polio prevention and risk management. Integrated global risk, economic, and poliovirus transmission modeling provides a tool to explore the dynamics of ending all use of one or more poliovirus vaccines to simplify the polio eradication endgame. RESEARCH DESIGN AND METHODS : With global reported cases of poliomyelitis trending higher since 2016, we apply an integrated global model to simulate prospective vaccine policies and strategies for OPV-using countries starting with initial conditions that correspond to the epidemiological poliovirus transmission situation at the beginning of 2022. RESULTS : Abruptly ending all OPV use in 2023 and relying only on IPV to prevent paralysis with current routine immunization coverage would lead to expected reestablished endemic transmission of poliovirus types 1 and 2, and approximately 150,000 expected cases of poliomyelitis per year. Alternatively, if OPV-using countries restart trivalent OPV (tOPV) use for all immunization activities and end IPV use, the model shows the lowest anticipated annual polio cases and lowest costs. CONCLUSIONS : Poor global risk management and coordination of OPV cessation remain a critical failure mode for the polio endgame, and national and global decision makers face difficult choices due to multiple available polio vaccine options and immunization strategies.
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Affiliation(s)
| | - Dhanya Dharmapalan
- Paediatric Infectious Diseases, Apollo Hospitals, Navi Mumbai 400614, India.
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Badizadegan K, Kalkowska DA, Thompson KM. Polio by the Numbers - A Global Perspective. J Infect Dis 2022; 226:1309-1318. [PMID: 35415741 PMCID: PMC9556648 DOI: 10.1093/infdis/jiac130] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 04/05/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Investments in national immunization programs and the Global Polio Eradication Initiative (GPEI) have resulted in substantial reductions in paralytic polio worldwide. However, cases prevented because of investments in immunization programs and GPEI remain incompletely characterized. METHODS Using a global model that integrates polio transmission, immunity, and vaccine dynamics, we provide estimates of polio incidence and numbers of paralytic cases prevented. We compare the results with reported cases and estimates historically published by the World Health Organization. RESULTS We estimate that the existence and use of polio vaccines prevented 5 million cases of paralytic polio between 1960-1987 and 24 million cases worldwide for 1988-2021 compared to a counterfactual world with no polio vaccines. Since the 1988 resolution to eradicate polio, our estimates suggest GPEI prevented 2.5 to 6 million cases of paralytic polio compared to counterfactual worlds without GPEI that assume different levels of intensity of polio vaccine use in routine immunization programs. DISCUSSION Analysis of historical cases provides important context for understanding and communicating the benefits of investments made in polio eradication. Prospective studies will need to explore the expected benefits of future investments, the outcomes of which will depend on whether and when polio is globally eradicated.
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Thompson KM, Kalkowska DA, Badizadegan K. Polio health economics: assessing the benefits and costs of polio, non-polio, and integrated activities of the Global Polio Eradication Initiative. Gates Open Res 2022; 6:5. [PMID: 35280345 PMCID: PMC8881365 DOI: 10.12688/gatesopenres.13524.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/25/2022] [Indexed: 01/03/2023] Open
Abstract
Background: Investments made by countries and donors to support polio eradication and the Global Polio Eradication Initiative (GPEI) over the past 35 years provided financial support for significant health interventions beyond the prevention of polio. Prior economic analyses that sought to quantify the economic benefits of some interventions encountered insufficient data and evidence associated with non-polio-specific activities. The 2022-2026 GPEI Strategic Plan explicitly identified integration and gender equity as funded mandates that must move forward in parallel with polio eradication, but these goals remain vaguely defined from a health economic perspective. Methods: To ensure unambiguous and full accounting for all financial investments in the GPEI, polio eradication, and other desirable objectives, we identify the health economic analysis methods and inputs needed to ensure transparent financial accountability and cost-effective use of funds. Results: Sufficient inputs and methods exist to characterize the health and economic benefits of polio-specific activities, but we identified the need for additional information and method development for some non-polio-specific and cost-sharing activities. Donors who seek to support non-polio-specific objectives as part of the GPEI may want to provide dedicated support financing for which it may be difficult to apply typical health economic criteria and to expect net health and/or net economic benefits. Conclusions: Given the mixture of funding sources provided to the GPEI, which includes support by governments and private donors, we recommend that the GPEI separately account for financial needs that represent necessities for polio eradication from those used for other stated objectives. An added layer of specificity that identifies all funds according to each activity, the accountable party and/or parties, and the associated measurable health or other outcome(s), will enable improved health economic analyses and reporting to donors who seek to track returns on their investments.
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Thompson KM. Polio eradication: what kind of world do we want? THE LANCET INFECTIOUS DISEASES 2022; 22:161-163. [PMID: 34648732 PMCID: PMC8504921 DOI: 10.1016/s1473-3099(21)00458-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 07/23/2021] [Indexed: 11/28/2022]
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Thompson KM, Badizadegan K. Health economic analyses of secondary vaccine effects: a systematic review and policy insights. Expert Rev Vaccines 2021; 21:297-312. [PMID: 34927511 DOI: 10.1080/14760584.2022.2017287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
INTRODUCTION : Numerous analyses demonstrate substantial health economic impacts of primary vaccine effects (preventing or mitigating clinical manifestations of the diseases they target), but vaccines may also be associated with secondary effects, previously known as non-specific, heterologous, or off-target effects. AREAS COVERED : We define key concepts to distinguish primary and secondary vaccine effects for health economic analyses, summarized terminology used in different fields, and perform a systematic review of health economic analyses focused on secondary vaccine effects (SVEs). EXPERT OPINION : Health economists integrate evidence from multiple fields, which often use incomplete or inconsistent definitions. Like regulators and policy makers, health economists require high-quality evidence of specific effects. Consistent with the limited evidence on mechanisms of action for SVEs, the associated health economic literature remains highly limited, with 4 studies identified by our systematic review. The lack of specific and well-controlled evidence that supports quantification of specific SVEs limits the consideration of these effects in vaccine research, development, regulatory, and recommendation decisions and health economic analyses.
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Wilson N, Mansoor OD, Boyd MJ, Kvalsvig A, Baker MG. We should not dismiss the possibility of eradicating COVID-19: comparisons with smallpox and polio. BMJ Glob Health 2021; 6:e006810. [PMID: 34373261 PMCID: PMC8375448 DOI: 10.1136/bmjgh-2021-006810] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 07/13/2021] [Indexed: 01/26/2023] Open
Affiliation(s)
- Nick Wilson
- Public Health, University of Otago Wellington, Wellington, New Zealand
| | | | | | - Amanda Kvalsvig
- Public Health, University of Otago Wellington, Wellington, New Zealand
| | - Michael G Baker
- Public Health, University of Otago Wellington, Wellington, New Zealand
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Kalkowska DA, Pallansch MA, Cochi SL, Thompson KM. Modeling Poliovirus Surveillance and Immunization Campaign Quality Monitoring Costs for Pakistan and Afghanistan for 2019-2023. Open Forum Infect Dis 2021; 8:ofab264. [PMID: 34295942 DOI: 10.1093/ofid/ofab264] [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: 04/07/2021] [Accepted: 05/19/2021] [Indexed: 11/13/2022] Open
Abstract
Background The Global Polio Eradication Initiative (GPEI) Strategic Plan for 2019-2023 includes commitments to monitor the quality of immunization campaigns using lot quality assurance sampling surveys (LQAS) and to support poliovirus surveillance in Pakistan and Afghanistan. Methods We analyzed LQAS and poliovirus surveillance data between 2016 and 2020, which included both acute flaccid paralysis (AFP) case-based detection and the continued expansion of environmental surveillance (ES). Using updated estimates for unit costs, we explore the costs of different options for future poliovirus monitoring and surveillance for Pakistan and Afghanistan. Results The relative value of the information provided by campaign quality monitoring and surveillance remains uncertain and depends on the design, implementation, and performance of the systems. Prospective immunization campaign quality monitoring (through LQAS) and poliovirus surveillance will require tens of millions of dollars each year for the foreseeable future for Pakistan and Afghanistan. Conclusions LQAS campaign monitoring as currently implemented in Pakistan and Afghanistan provides limited and potentially misleading information about immunization quality. AFP surveillance in Pakistan and Afghanistan provides the most reliable evidence of transmission, whereas ES provides valuable supplementary information about the extent of transmission in the catchment areas represented at the time of sample collection.
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Affiliation(s)
| | - Mark A Pallansch
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Stephen L Cochi
- Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Thompson KM, Kalkowska DA, Badizadegan K. Hypothetical emergence of poliovirus in 2020: part 1. Consequences of policy decisions to respond using nonpharmaceutical interventions. Expert Rev Vaccines 2021; 20:465-481. [PMID: 33624568 DOI: 10.1080/14760584.2021.1891888] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVES As efforts to control COVID-19 continue, we simulate hypothetical emergence of wild poliovirus assuming an immunologically naïve population. This differs from the current global experience with polio and serves as a model for responding to future pandemics. METHODS Applying an established global model, we assume a fully susceptible global population to polioviruses, independently introduce a virus with properties of each of the three stable wild poliovirus serotypes, and explore the impact of strategies that range from doing nothing to seeking global containment and eradication. RESULTS We show the dynamics of paralytic cases as the virus spreads globally. We demonstrate the difficulty of eradication unless aggressive efforts begin soon after initial disease detection. Different poliovirus serotypes lead to different trajectories and burdens of disease. In the absence of aggressive measures, the virus would become globally endemic in 2-10 years, and cumulative paralytic cases would exceed 4-40 million depending on serotype, with the burden of disease shifting to younger ages. CONCLUSIONS The opportunity to eradicate emerging infections represents an important public policy choice. If the world first observed the emergence of wild poliovirus in 2020, adopting aggressive control strategies would have been required to prevent a devastating global pandemic.
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The impact of disruptions caused by the COVID-19 pandemic on global polio eradication. Vaccine 2021; 41 Suppl 1:A12-A18. [PMID: 33962838 PMCID: PMC10045205 DOI: 10.1016/j.vaccine.2021.04.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 03/29/2021] [Accepted: 04/14/2021] [Indexed: 12/21/2022]
Abstract
In early 2020, the COVID-19 pandemic led to substantial disruptions in global activities. The disruptions also included intentional and unintentional reductions in health services, including immunization campaigns against the transmission of wild poliovirus (WPV) and persistent serotype 2 circulating vaccine-derived poliovirus (cVDPV2). Building on a recently updated global poliovirus transmission and Sabin-strain oral poliovirus vaccine (OPV) evolution model, we explored the implications of immunization disruption and restrictions of human interactions (i.e., population mixing) on the expected incidence of polio and on the resulting challenges faced by the Global Polio Eradication Initiative (GPEI). We demonstrate that with some resumption of activities in the fall of 2020 to respond to cVDPV2 outbreaks and full resumption on January 1, 2021 of all polio immunization activities to pre-COVID-19 levels, the GPEI could largely mitigate the impact of COVID-19 to the delays incurred. The relative importance of reduced mixing (leading to potentially decreased incidence) and reduced immunization (leading to potentially increased expected incidence) depends on the timing of the effects. Following resumption of immunization activities, the GPEI will likely face similar barriers to eradication of WPV and elimination of cVDPV2 as before COVID-19. The disruptions from the COVID-19 pandemic may further delay polio eradication due to indirect effects on vaccine and financial resources.
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Thompson KM. Modeling and Managing Poliovirus Risks: We are Where we are…. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2021; 41:223-228. [PMID: 33590520 PMCID: PMC7894995 DOI: 10.1111/risa.13668] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 08/28/2020] [Indexed: 05/07/2023]
Abstract
This introduction for the third special issue on modeling poliovirus risks provides context for the current status of global polio eradication efforts and gives an overview of the individual papers included in the issue. Although risk analysis continues to support the Global Polio Eradication Initiative (GPEI), efforts to finish the job remained off track at the beginning of 2020 and prior to the COVID-19 pandemic, as discussed in the special issue. The disruptions associated with COVID-19 occurring now will inevitably change the polio eradication trajectory, and future studies will need to characterize the impacts of these disruptions on the polio endgame.
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Thompson KM, Kalkowska DA, Badizadegan K. No Role for Reintroducing OPV into the United States with Respect to Controlling COVID-19 [Response to the letter to the Editor by Chumakov et al.]. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2021; 41:389-392. [PMID: 33590518 PMCID: PMC8014295 DOI: 10.1111/risa.13671] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 12/14/2020] [Indexed: 05/04/2023]
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Kalkowska DA, Thompson KM. Health and Economic Outcomes Associated with Polio Vaccine Policy Options: 2019-2029. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2021; 41:364-375. [PMID: 33590519 PMCID: PMC7895457 DOI: 10.1111/risa.13664] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 12/04/2020] [Indexed: 05/08/2023]
Abstract
The polio endgame remains complicated, with many questions about future polio vaccines and national immunization policies. We simulated possible future poliovirus vaccine routine immunization policies for countries stratified by World Bank Income Levels and estimated the expected costs and cases using an updated integrated dynamic poliovirus transmission, stochastic risk, and economic model. We consider two reference cases scenarios: one that achieves the eradication of all wild polioviruses (WPVs) by 2023 and one in which serotype 1 WPV (WPV1) transmission continues. The results show that the addition of inactivated poliovirus vaccine (IPV) to routine immunization in all countries substantially increased the expected costs of the polio endgame, without substantially increasing its expected health or economic benefits. Adding a second dose of IPV to the routine immunization schedules of countries that currently include a single IPV dose further increases costs and does not appear economically justified in the reference case that does not stop WPV transmission. For the reference case that includes all WPV eradication, adding a second IPV dose at the time of successful oral poliovirus vaccine (OPV) cessation represents a cost-effective option. The risks and costs of needing to restart OPV use change the economics of the polio endgame, although the time horizon used for modeling impacts the overall economic results. National health leaders will want to consider the expected health and economic net benefits of their national polio vaccine strategies recognizing that preferred strategies may differ.
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