Progress Toward Polio Eradication - Worldwide, January 2017-March 2019

Immune Response of Inactivated Rabies Vaccine Inoculated via Intraperitoneal, Intramuscular, Subcutaneous and Needle-Free Injection Technology-Based Intradermal Routes in Mice

Inoculation routes may significantly affect vaccine performance due to the local microenvironment, antigen localization and presentation, and, therefore, final immune responses. In this study, we conducted a head-to-head comparison of immune response and safety of inactivated rabies vaccine inoculated via intraperitoneal (IP), intramuscular (IM), subcutaneous (SC) and needle-free injection technology-based intradermal (ID) routes in ICR mice. Immune response was assessed in terms of antigen-specific antibodies, antibody subtypes and neutralizing antibodies for up to 28 weeks. A live rabies virus challenge was also carried out to evaluate vaccine potency. The dynamics of inflammatory cell infiltration at the skin and muscle levels were determined via histopathological examination. The kinetics and distribution of a model antigen were also determined by using in vivo fluorescence imaging. Evidence is presented that the vaccine inoculated via the ID route resulted in the highest antigen-specific antibody and neutralizing antibody titers among all administration routes, while IP and IM routes were comparable, followed by the SC route. Antibody subtype analysis shows that the IP route elicited a Th1-biased immune response, while SC and IM administration elicited a prominent Th2-type immune response. Unexpectedly, the ID route leads to a balanced Th1 and Th2 immune response. In addition, the ID route conferred effective protection against lethal challenge with 40 LD50 of the rabies CVS strain, which was followed by IP and IM routes. Moreover, a one-third dose of the vaccine inoculated via the ID route provided comparable or higher efficacy to a full dose of the vaccine via the other three routes. The superior performance of ID inoculation over other routes is related to longer local retention at injection sites and higher lymphatic drainage. Histopathology examination reveals a transient inflammatory cell infiltration at ID and IM injection sites which peaked at 48 h and 24 h, respectively, after immunization, with all side effects disappearing within one week. These results suggest that needle-free injection technology-based ID inoculation is a promising strategy for rabies vaccination in regard to safety and efficacy.

Sensitive poliovirus detection using nested PCR and nanopore sequencing: a prospective validation study

Timely detection of outbreaks is needed for poliovirus eradication, but gold standard detection in the Democratic Republic of the Congo takes 30 days (median). Direct molecular detection and nanopore sequencing (DDNS) of poliovirus in stool samples is a promising fast method. Here we report prospective testing of stool samples from suspected polio cases, and their contacts, in the Democratic Republic of the Congo between 10 August 2021 and 4 February 2022. DDNS detected polioviruses in 62/2,339 (2.7%) of samples, while gold standard combination of cell culture, quantitative PCR and Sanger sequencing detected polioviruses in 51/2,339 (2.2%) of the same samples. DDNS provided case confirmation in 7 days (median) in routine surveillance conditions. DDNS enabled confirmation of three serotype 2 circulating vaccine-derived poliovirus outbreaks 23 days (mean) earlier (range 6-30 days) than the gold standard method. The mean sequence similarity between sequences obtained by the two methods was 99.98%. Our data confirm the feasibility of implementing DDNS in a national poliovirus laboratory.

Recent Advancements and Novel Approaches Contributing to the Present Arsenal of Prophylaxis and Treatment Strategies Against Category A Bacterial Biothreat Agents

Bacterial pathogens have always been a part of the ecosystem in which we thrive. Some pathogens have caused deadly outbreaks in the past and have been exploited as an agent of threat. Natural hotspots for these biological pathogens are widely distributed throughout the world and hence they remain clinically important. Technological advancement and change in general lifestyle has driven the evolution of these pathogens into more virulent and resistant variants. There has been a growing concern over the development of multidrug-resistant bacterial strains that could be used as bioweapons. This rapid change in pathogens also propels the field of science to develop and innovate new strategies and methodologies which are superior and safer to the existing ones. Some bacterial agents like-Bacillus anthracis, Yersinia pestis, Francisella tularensis and toxins produced by strains of Clostridium botulinum, have been segregated as Category A substances as they pose imminent threat to public health with a history of life threatening and catastrophic disease. This review highlights some encouraging developments and value additions in the current plan of action for protection against these select biothreat bacterial pathogens.

Protease-Independent Production of Poliovirus Virus-like Particles in Pichia pastoris: Implications for Efficient Vaccine Development and Insights into Capsid Assembly

The production of enterovirus virus-like particles (VLPs) that lack the viral genome have great potential as vaccines for a number of diseases, such as poliomyelitis and hand, foot, and mouth disease. These VLPs can mimic empty capsids, which are antigenically indistinguishable from mature virions, produced naturally during viral infection. Both in infection and in vitro, capsids and VLPs are generated by the cleavage of the P1 precursor protein by a viral protease. Here, using a stabilized poliovirus 1 (PV-1) P1 sequence as an exemplar, we show the production of PV-1 VLPs in Pichia pastoris in the absence of the potentially cytotoxic protease, 3CD, instead using the porcine teschovirus 2A (P2A) peptide sequence to terminate translation between individual capsid proteins. We compare this to protease-dependent production of PV-1 VLPs. Analysis of all permutations of the order of the capsid protein sequences revealed that only VP3 could be tagged with P2A and maintain native antigenicity. Transmission electron microscopy of these VLPs reveals the classic picornaviral icosahedral structure. Furthermore, these particles were thermostable above 37°C, demonstrating their potential as next generation vaccine candidates for PV. Finally, we believe the demonstration that native antigenic VLPs can be produced using protease-independent methods opens the possibility for future enteroviral vaccines to take advantage of recent vaccine technological advances, such as adenovirus-vectored vaccines and mRNA vaccines, circumventing the potential problems of cytotoxicity associated with 3CD, allowing for the production of immunogenic enterovirus VLPs in vivo. IMPORTANCE The widespread use of vaccines has dramatically reduced global incidence of poliovirus infections over a period of several decades and now the wild-type virus is only endemic in Pakistan and Afghanistan. However, current vaccines require the culture of large quantities of replication-competent virus for their manufacture, thus presenting a potential risk of reintroduction into the environment. It is now widely accepted that vaccination will need to be extended posteradication into the foreseeable future to prevent the potentially catastrophic reintroduction of poliovirus into an immunologically naive population. It is, therefore, imperative that novel vaccines are developed which are not dependent on the growth of live virus for their manufacture. We have expressed stabilized virus-like particles in yeast, from constructs that do not require coexpression of the protease. This is an important step in the development of environmentally safe and commercially viable vaccines against polio, which also provides some intriguing insights into the viral assembly process.

Suboptimal Serologic Immunity Against Poliomyelitis Among New Migrant Children in Greece Calls for Organized Action

BACKGROUND

Migration-flows pose the risk of poliovirus reintroduction from endemic countries to Greece. This study aims to evaluate serologic-immunity/vaccination against poliomyelitis in newly-arriving migrant children.

METHODS

Demographic-immunisation data and blood-serum were obtained from migrants 1-14years-old, referred to a hospital-clinic in Athens-Greece within three months from arrival. Immunity to polioviruses-1-3 was determined by serum-neutralizing-antibodies(WHO guidelines). Titers ≥ 1:8 were considered positive.

RESULTS

From 9/2010 to 9/2013, 274 children(150 refugees/124 immigrants), mean age 7.1years-old, were enrolled. Only 57(20.8%) of them presented with vaccination-records. Children originated mainly from Asia(n = 198), Eastern Europe(n = 28), Middle East(n = 24) and Africa(n = 24) with 160(58.4%) from polio-endemic-countries(Afghanistan-112(40.8%), Pakistan-24(8.8%) and India-24(8.8%)). Seropositivity against polio-1-2&3 was 84.3%, 86.1% and 74.5%, respectively. Immigrants, had higher seroprotective rates against polioviruses-1-2&3 than refugees(polio-1:p = 0.002;polio-2:p = 0.004,polio-3:p < 0.001). Seronegativity to 1PVs-2PVs and all three polio serotypes was found in 37(13.5%),12 (4.4%), and 30 children(10.9%) respectively. Increasing number of vaccine-doses, and younger-age, were positively-associated with seropositivity.

DISCUSSION

A remarkable fraction of newly-arrived migrant-children were seronegative to one or more polioviruses.

Vaccine Hesitancy and Perceptions of the Community about Polio in High-Risk Areas of Karachi, Sindh, Pakistan

The study aimed to determine the reasons for polio vaccine hesitancy among parents of persistently missed children (PMCs) in the high-risk areas of Karachi, Pakistan. A cross-sectional survey of parents of PMCs was conducted in April 2019 in 34 high-risk union councils of Karachi. PMCs were randomly selected from the polio program database, and further information was collected on a questionnaire by trained staff using face-to-face interviews with parents of PMCs. A total of 325 participants were included in the study. Among refusals, 112 (37.3%) had no trust in vaccine quality, followed by 45 (15.0%) who were afraid of side effects, 42 (14.0%) whose elders did not allow polio vaccination, 39 (13.0%) who refused due to the influence of negative social media videos, and 20 (6.7%) who had no trust in polio teams. We concluded that misconception is still a big challenge, and the program needs to strive for community acceptance. Low levels of trust in vaccines and teams as well as fear of OPV side effects were among the main reason for vaccine hesitancy. The participant communities recommended involving famous medical doctors, religious influencers, and TV or sports stars to enhance knowledge and acceptance of polio vaccination.

Immunogenicity of Catch-Up Immunization with Conventional Inactivated Polio Vaccine among Japanese Adults

Most Japanese adults are vaccinated twice with the Sabin trivalent oral polio vaccine. Booster vaccination is recommended for Japanese travelers to polio-endemic/high-risk countries. We assessed the catch-up immunization of healthy Japanese adults aged ≥20 years with two doses of standalone conventional inactivated polio vaccine (cIPV). Immunogenicity was evaluated by serum neutralization titers (pre-booster vaccination, 4-6 weeks after each vaccination) against type 1, 2, and 3 poliovirus strains. The participants were 61 healthy Japanese adults (26 men/35 women; mean age ± standard deviation age 35.8 ± 8.0 years). Seropositivity rates (percentage of participants with anti-poliovirus antibody titers ≥1:8) pre-vaccination were 88.5%, 95.1%, and 52.5% for Sabin strains (type 1, 2, and 3); 72.1%, 93.4%, and 31.1% for virulent poliovirus strains (type 1: Mahoney; type 2: MEF-1; and type 3: Saukett); and 93.4%, 93.4%, 93.4%, and 88.5% for type 2 vaccine-derived poliovirus strains (SV3128, SV3130, 11,196, and 11,198). After one cIPV dose, all seropositivity rates increased to 98.4-100.0%. After two cIPV doses, the seropositivity rates reached 100% for all strains. cIPV was well tolerated, with no safety concerns. Catch-up immunization with standalone cIPV induced robust immune responses in Japanese adults, indicating that one booster dose boosted serum-neutralizing antibodies to many strains.

Importance of Population Education in Implementation of Compulsory Immunization Against Polyomyelitis in Children

Poliomyelitis is a contagious disease characterized by the appearance of fever, malaise, scratching in the throat, gastrointestinal signs, and after a few days the appearance of muscle paralysis, as well as respiratory and vasomotor disorders. Today, this disease is very rare, due to systemic active immunization. The aim of this study was to assess the level of knowledge and attitudes toward poliomyelitis and importance of immunization against it.

A specially designed survey questionnaire was used for interviewing purposes. Data analysis and processing were performed using a statistical data processing package (SPSS for Windows, version 20). A chi-square test was used from the statistical tests.

The educated profile of the respondents was as follows: medical sciences - 37 (50%), natural sciences and mathematics - 6 (8,1%), social sciences - 5 (6,8%), technical sciences - 19 (25,7%) and arts - 7 (9,5%). The study findings indicate a high level of awareness and knowledge of the population regarding polio, as well as good health awareness of the population about immunization i.e. polio vaccination. 34 respondents from the field of medical education answered the question exactly how the vaccine protects against the disease. In the field of natural mathematical sciences, a total of 3 gave the correct answer, which makes 50% of the total number of persons (6) in the mentioned field. In addition, majority of the study sample (70,3%) is aware that child should be vaccinated. Furthermore, 91,9% of respondents agree that education of parents regarding children vaccination is of great importance for whole community.

Based on findings of present study it can be concluded that efforts still need to be made in education of the wider population toward polio and the importance of vaccination. In addition to healthcare professionals, the entire community should participate in this strategic task.

Plant-made poliovirus vaccines - Safe alternatives for global vaccination

Human polioviruses are highly infectious viruses that are spread mainly through the fecal-oral route. Infection of the central nervous system frequently results in irreversible paralysis, a disease called poliomyelitis. Children under five years are mainly affected if they have not acquired immunity through natural infection or via vaccination. Current polio vaccines comprise the injectable inactivated polio vaccine (IPV, also called the Salk vaccine) and the live-attenuated oral polio vaccine (OPV, also called the Sabin vaccine). The main limitations of the IPV are the reduced protection at the intestinal mucosa, the site of virus replication, and the high costs for manufacturing due to use of live viruses. While the OPV is more effective and stimulates mucosal immunity, it is manufactured using live-attenuated strains that can revert into pathogenic viruses resulting in major safety concerns and vaccine-derived outbreaks. During the last fifteen years, plant-based poliovirus vaccines have been explored by several groups as a safe and low-cost alternative, and promising results in protection against challenges with viruses and induction of neutralizing antibodies have been obtained. However, low yields and a high frequency in dose administration highlight the need for improvements in polioviral antigen production. In this review, we provide insights into recent efforts to develop plant-made poliovirus candidates, with an emphasis on strategies to optimize the production of viral antigens.

Production and Characterisation of Stabilised PV-3 Virus-like Particles Using Pichia pastoris

Following the success of global vaccination programmes using the live-attenuated oral and inactivated poliovirus vaccines (OPV and IPV), wild poliovirus (PV) is now only endemic in Afghanistan and Pakistan. However, the continued use of these vaccines poses potential risks to the eradication of PV. The production of recombinant PV virus-like particles (VLPs), which lack the viral genome offer great potential as next-generation vaccines for the post-polio world. We have previously reported production of PV VLPs using Pichia pastoris, however, these VLPs were in the non-native conformation (C Ag), which would not produce effective protection against PV. Here, we build on this work and show that it is possible to produce wt PV-3 and thermally stabilised PV-3 (referred to as PV-3 SC8) VLPs in the native conformation (D Ag) using Pichia pastoris. We show that the PV-3 SC8 VLPs provide a much-improved D:C antigen ratio as compared to wt PV-3, whilst exhibiting greater thermostability than the current IPV vaccine. Finally, we determine the cryo-EM structure of the yeast-derived PV-3 SC8 VLPs and compare this to previously published PV-3 D Ag structures, highlighting the similarities between these recombinantly expressed VLPs and the infectious virus, further emphasising their potential as a next-generation vaccine candidate for PV.

CaFÉ: A Sensitive, Low-Cost Filtration Method for Detecting Polioviruses and Other Enteroviruses in Residual Waters

Acute flaccid paralysis (AFP) surveillance has been used to identify polio cases and target vaccination campaigns since the inception of the Global Poliovirus Eradication Initiative (GPEI) in 1988. To date, only Afghanistan and Pakistan have failed to interrupt wild poliovirus transmission. Circulation of vaccine-derived polioviruses (VDPV) continues to be a problem in high-risk areas of the Eastern Mediterranean, African, and Southeast Asian regions. Environmental surveillance (ES) is an important adjunct to AFP surveillance, helping to identify circulating polioviruses in problematic areas. Stools from AFP cases and contacts (>200,000 specimens/year) and ES samples (>642 sites) are referred to 146 laboratories in the Global Polio Laboratory Network (GPLN) for testing. Although most World Health Organization supported laboratories use the two-phase separation method due to its simplicity and effectiveness, alternative simple, widely available, and cost-effective methods are needed. The CAFÉ (Concentration and Filtration Elution) method was developed from existing filtration methods to handle any type of sewage or residual waters. At $10-20 US per sample for consumable materials, CAFÉ is cost effective, and all equipment and reagents are readily available from markets and suppliers globally. The report describes the results from a parallel study of CAFÉ method with the standard two-phase separation method. The study was performed with samples collected from five countries (Guatemala, Haïti, Thailand, Papua New Guinea, and the Philippines), run in three laboratories-(United States, Thailand and in the Philippines) to account for regional and sample-to-sample variability. Samples from each site were divided into two 500 ml aliquots and processed by both methods, with no other additional concentration or manipulation. The results of 338 parallel-tested samples show that the CAFÉ method is more sensitive than the two-phase separation method for detection of non-polio enteroviruses (p-value < 0.0001) and performed as well as the two-phase separation method for polioviruses detection with no significant difference (p-value > 0.05). The CAFÉ method is a robust, sensitive, and cost-effective method for isolating enteroviruses from residual waters.

Polio eradication in a chronic conflict setting lessons from the Republic of South Sudan, 2010-2020

INTRODUCTION

in 1988 the World Health Assembly set an ambitious target to eradicate Wild Polio Virus (WPV) by 2000, following the successful eradication of the smallpox virus in 1980. South Sudan and the entire African region were certified WPV free on August 25, 2020. South Sudan has maintained its WPV free status since 2010, and this paper reviewed the country's progress, outlined lessons learned, and describes the remaining challenges in polio eradication.

METHODS

secondary data analysis was conducted using the Ministry of Health and WHO polio surveillance datasets, routine immunisation coverage, polio campaign data, and surveys from 2010 to 2020. Relevant technical documents and reports on polio immunisation and surveillance were also reviewed. Data analysis was conducted using EPI Info 7 software.

RESULTS

administrative routine immunisation coverage for bivalent Oral Polio Vaccine (OPV) 3rd dose declined from 77% in 2010 to 56% in 2020. In contrast, the administrative and post-campaign evaluation coverage recorded for the nationwide supplemental polio campaigns since 2011 was consistently above 85%; however, campaigns declined in number from four in 2011 to zero in 2020. Overall, 76% of notified cases of Acute Flaccid Paralysis (AFP) received three or more doses of the oral polio vaccine. The Annualized Non-AFP rate ranged between 4.0 to 5.4 per 100,000 under 15 years populations, and stool adequacy ranged from 83% to 94%.

CONCLUSION

South Sudan's polio-free status documentation was accepted by the ARCC in 2020, thereby enabling the African Region to be certified WPV free on August 25, 2020. However, there are concerns as the country continues to report low routine immunisation coverage and a reduction in the number of polio campaigns conducted each year. It is recommended that the country conduct high-quality nationwide supplemental polio campaigns yearly to achieve and maintain the required herd immunity. It invests in its routine immunisation program while ensuring optimal AFP surveillance performance indicators.

Poliovirus non-permissive CD155 knockout cells derived from RD cell line for handling poliovirus potentially infectious materials in virology laboratories

STATEMENTS OF THE PROBLEM

Destruction of all poliovirus containing materials, safe and secure handling of retained polioviruses for vaccine production and research will be obligatory to eliminate facility-associated risks. Polioviruses and poliovirus potentially infectious materials (PIM) include fecal or respiratory samples requiring containment have been defined in WHO-GAPIII documents. Non-polio laboratories culturing viruses from PIM are most affected as cell cultures of human and monkey origin are also poliovirus permissive.

METHOD OF STUDY

CRISPR gene-editing technology was used to knockout the poliovirus receptor (PVR/CD155) gene in RD cell line. PVR knockout RD cell susceptibility was tested using known non-polio enterovirus types. A selected clone (RD-SJ40) was field evaluated for virus isolation from 626 stool samples of AFP cases.

RESULTS

Poliovirus non-permissive cells derived from RD cell line did not show CD155-specific cell-surface immunofluorescence. CD155 gene sequencing confirmed nucleotide base pair deletions within exon2 and exon3. The CD155 knockout RD-SJ40 cells did not support the growth of poliovirus from positive stool samples. All NPEV types were isolated in RD and RD-SJ40 cells.

CONCLUSION

CRISPR correctly edited CD155 gene of RD cells to render them poliovirus non-permissive while susceptibility to NPEV remained unchanged. RD-SJ40 cells are safe for NPEV isolation from poliovirus PIM without derogating GAPIII containment requirements. This article is protected by copyright. All rights reserved.

Facilitators and barriers of infectious diseases surveillance activities: lessons from the Global Polio Eradication Initiative - a mixed-methods study

OBJECTIVES

To document lessons from the Global Polio Eradication Initiative (GPEI) by determining factors associated with successful surveillance programme globally as well as at national and subnational levels. The process of conducting surveillance has been previously recognised in the literature as important for the success of polio surveillance activities.

DESIGN

A cross-sectional survey with closed and open-ended questions.

SETTINGS

Survey of persons involved in the implementation of surveillance activities under the GPEI at the global level and in seven low-income and middle-income countries.

PARTICIPANTS

Individuals (n=802) with ≥12 months of experience implementing surveillance objective of the GPEI between 1988 and 2019.

MAIN OUTCOME MEASURES AND METHODS

Quantitative and qualitative analyses were conducted. Logistic regression analyses were used to assess factors associated with implementation process as a factor for successful surveillance programme. Horizontal analysis was used to analyse qualitative free-text responses on facilitators and barriers identified for conducting surveillance activities successfully.

RESULTS

Overall, participants who reported challenges relating to GPEI programme characteristics had 50% lower odds of reporting implementation process as a factor for successful surveillance (adjusted OR (AOR): 0.50, 95% CI: 0.29 to 0.85). Challenges were mainly perceptions of external intervention source (ie, surveillance perceived as 'foreign' to local communities) and the complexity of surveillance processes (ie, surveillance required several intricate steps). Those who reported organisational challenges were almost two times more likely to report implementation process as a factor for successful surveillance (AOR: 1.89, 95% CI: 1.07 to 3.31) overall, and over threefolds (AOR: 3.32, 95% CI: 1.14 to 9.66) at the national level.

CONCLUSIONS

Programme characteristics may have impeded the process of conducting surveillance under the GPEI, while organisational characteristics may have facilitated the process. Future surveillance programmes should be designed with inputs from local communities and frontline implementers.

Planning and implementing a targeted polio vaccination campaign for Somali mobile populations in Northeastern Kenya based on migration and settlement patterns

Supporting the global eradication of wildpoliovrisu (WPV), this project aimed to provide polio and measles vaccines to a population frequenty missed by immunization services and campaigns, ethnic Somali children living among mobile populations within Kenya's Northeastern Region. Additionally, nutritional support, albendazole (for treatment of intestinal parasites) and vitamin A were provided to improve children's health and in accordance with regional vaccination campaign practices. To better understand movement patterns and healthcare-seeking behaviors within this population, we trained community-based data collectors in qualitative and geospatial data collection methods. Data collectors conducted focus group and participatory mapping discussions with ethnic Somalis living in the region. Qualitative and geospatial data indicated movement patterns that followed partially definable routes and temporary settlement patterns with an influx of ethnic Somali migrants into Kenya at the start of the long rainy season (April-June). Community members also reported concerns about receiving healthcare services in regional health facilities. Using these data, an 8-week vaccination campaign was planned and implemented: 2196 children aged 0-59 months received polio vaccine (9% had not previously received polio vaccine), 2524 children aged 9-59 months received measles vaccine (27% had not previously received measles vaccine), 113 were referred for the treatment of severe acute malnourishment, 150 were referred to a supplementary feeding program due to moderate acute malnourishment, 1636 children aged 12-59 months were provided albendazole and 2008 children aged 6-59 months were provided with vitamin A. This project serves as an example for how community-based data collectors and local knowledge can help adapt public health programming to the local context and could aid disease eradication in at-risk populations.

Relationship Between Helicobacter pylori IgG Seroprevalence and the Immune Response to Poliovirus Vaccine Among School-Age Children From a Population With Near-Universal Immunity Level

Objectives

To examine the association between Helicobacter pylori seroprevalence and serum pepsinogens (PGs) as markers of gastric inflammation), with high neutralizing antibody titers to poliovirus type 1 and 3 vaccine strains among children age 3–4 years, subsequent to sub-clinical infection acquired during a wild-type poliovirus type 1 outbreak in Israel.

Methods

A serosurvey was conducted among 336 children aged 5–17 years who were vaccinated with both inactivated polio vaccine and oral polio vaccines. H. pylori serum IgG antibodies and PG concentrations were measured using ELISA. Neutralizing antibodies to poliovirus vaccine strains were measured and children with a titer ≥1:8 were considered immune. High-level immunity was defined as having a serum NA titer >1:2048. Propensity score inverse weighting was used to account for confounders.

Results

Neutralizing antibodies titers ≥1:8 to poliovirus type 1 and 3 vaccine strains were found in 99.4 and 98.2% of the children, respectively. An inverse association was found between H. pylori seropositivity accompanied by PGI:PGII ratio ≤6.5 (marker of gastric inflammation) and high-level immunity to poliovirus type 1: OR 0.39 (95% CI 0.68–0.91), p = 0.027. The association between H. pylori seropositivity of CagA virulent phenotype and polio high immunity was not significant. The association between H. pylori seropositivity and high neutralizing antibodies to type 3 poliovirus was of low magnitude and not significant.

Conclusions

H. pylori seroprevalence accompanied by evidence of gastric inflammation was inversely correlated with high titers of neutralizing antibodies to poliovirus in children from a population with near universal polio immunity.

Attitude and perception towards vaccination against poliomyelitis in Peshawar, Pakistan

OBJECTIVE:

This research aimed to quantitatively assess the general public's awareness, attitude and perception of polio and its vaccination in Peshawar KPK, Pakistan.

METHODS:

We conducted a survey-based study to understand the surge in polio cases from 2015 to 2019 in the Peshawar city of the Khyber Pakhtunkhwa (KPK), Pakistan. A pre-tested questionnaire-based study was conducted in 2019 to assess the attitude and general perception of residents of Peshawar KPK towards polio vaccination.

RESULTS:

Out of 241 country-wide polio cases, 63 (26.1%) polio cases were reported in Peshawar city from 2015–2019. The questionnaire revealed that individuals between 18–30 years of age had sufficient knowledge (65.1%) about polio. Male and female participants had equal awareness (~ 43%). Participants with higher education (45.9%), those with better financial status (49.5%), individuals with children < 5 years of age (46.4%), and those who had experience of a polio patient (63.1%) had better knowledge. Participants inhabiting the central city were better aware (50.5%) of polio than individuals living in the outskirts.

CONCLUSION:

The data indicated that poor knowledge and negative attitudes of people towards polio vaccination are the main causes of the polio eradication program's failure. Moreover, religious beliefs, unchecked migration between the Pak-Afghan border, and lack of knowledge about polio vaccination are identified as critical barriers to polio eradication.

Assessing the impact of polio supplementary immunisation activities on routine immunisation and health systems: a systematic review

Introduction

The Global Polio Eradication Initiative uses polio supplementary immunisation activities (SIAs) as a strategy to increase vaccine coverage and cease poliovirus transmission. Impact of polio SIAs on immunisation systems is frequently debated. We reviewed the impact of polio SIAs on routine immunisation and health systems during the modern era of polio eradication.

Methods

We searched nine databases for studies reporting on polio SIAs and immunisation coverage, financial investment, workforce and health services delivery. We conducted a narrative synthesis of evidence. Records prior to 1994, animal, modelling or case studies data were excluded.

Results

20/1637 unique records were included. Data on vaccine coverage were included in 70% (14/20) studies, workforce in 65% (13/20) and health services delivery in 85% (17/20). SIAs positively contributed to vaccination uptake of non-polio vaccines in seven studies, neutral in three and negative in one. Some polio SIAs contributed to workforce strengthening through training and capacity building. Polio SIAs were accompanied with increased social mobilisation and community awareness building confidence in vaccination programmes. Included studies were programmatic in nature and contained variable data, thus could not be justly critically appraised.

Conclusion

Polio SIAs are successful at increasing polio vaccine coverage, but the resources and infrastructures were not always utilised for delivery of non-polio vaccines and integration into routine service delivery. We found a gap in standardised tools to evaluate SIAs, which can then inform service integration. Our study provides data to inform SIAs evaluations, and provides important considerations for COVID-19 vaccine roll-out to strengthen health systems.

PROSPERO registration number

CRD42020152195.

Enhancing acute flaccid paralysis surveillance system towards polio eradication: reverse cold chain monitoring in Nigeria, 2017 to 2019

INTRODUCTION

Highly sensitive acute flaccid paralysis (AFP) surveillance is critical for detection of poliovirus circulation and documentation for polio-free certification. The reverse cold chain (RCC) is a system designed to maintain stool specimens in appropriate temperature for effective detection of poliovirus in the laboratory. We monitored the RCC of AFP surveillance in Nigeria to determine its effectiveness in maintaining viability of enterovirus.

METHODS

A descriptive cross-sectional study was conducted from November 2017 to December 2019. We included AFP cases from 151 Local Government Areas and monitored RCC of paired stool specimens from collection to arrival at laboratories. The national guideline recommends RCC temperature of +2 to +8°C and a non-polio enterovirus (NPENT) detection rate of ≥10%. We analyzed data with Epi Info 7, and presented results as frequencies and proportions, using Chi-square statistic to test for difference in enterovirus isolation.

RESULTS

Of the 1,042 tracked paired stool specimens, 1,038(99.6%) arrived at the laboratory within 72 hours of collection of second specimen, 824(79.1%) were maintained within recommended temperature range, and 271(26%) yielded enteroviruses: 200(73.8%) NPENT, 66(24.4%) Sabin, 3(1.1%) vaccine derived poliovirus type 2 and 2(0.7%) mixture of Sabin and NPENT. The NPENT and Sabin rates were 19.2% and 6.7% respectively. Twenty-five percent of 824 specimens maintained within recommended temperature range, compared with 29.8% of 218 specimens with temperature excursion yielded enteroviruses (P=0.175).

CONCLUSION

the RCC of AFP surveillance system in the study area was optimal and effective in maintaining the viability of enteroviruses. It was unlikely that poliovirus transmission was missed during the intervention.

To be, or not to be… Guillain-Barré Syndrome

Guillain-Barré Syndrome (GBS) is currently the most frequent cause of acute flaccid paralysis on a global scale, being an autoimmune disorder wherein demyelination of the peripheral nerves occurs. Its main clinical features are a symmetrical ascending muscle weakness with reduced osteotendinous reflexes and variable sensory involvement. GBS most commonly occurs after an infection, especially viral (including COVID-19), but may also transpire after immunization with certain vaccines or in the development of specific malignancies. Immunoglobulins, plasmapheresis, and glucocorticoids represent the principal treatment modalities, however patients with severe disease progression may require supportive therapy in an intensive care unit. Due to its symptomology, which overlaps with numerous neurological and infectious illnesses, the diagnosis of GBS may often be misattributed to pathologies that are essentially different from this syndrome. Moreover, many of these require specific treatment methods distinct to those recommended for GBS, in lack of which the prognosis of the patient is drastically affected. Such diseases include exposure to toxins either environmental or foodborne, central nervous system infections, metabolic or serum ion alterations, demyelinating pathologies, or even conditions amenable to neurosurgical intervention. This extensive narrative review aims to systematically and comprehensively tackle the most notable and challenging differential diagnoses of GBS, emphasizing on the clinical discrepancies between the diseases, the appropriate paraclinical investigations, and suitable management indications.

The association of online search interest with polio cases and vaccine coverage: an infodemiological and ecological study

Achievement of universal eradication of paralytic poliomyelitis has remained a challenge. Despite the general decline in cases, multiple outbreaks attributed to poor vaccination still occur. Noncompliance from vaccination can be improved through education on various media platforms. In the internet age, online health-seeking behavior plays a significant role in this regard. Hence, our study investigated the association between global online search interest in polio with the number of polio cases and vaccination coverage. This infodemiological and ecological study utilized Google Trends' search volume index (SVI) for "polio" and the World Health Organization data on the number of polio cases (PC) and vaccine coverage rate (VCR) per country between 2006 and 2019. Associations between SVI for "polio" with PC and with VCR were evaluated. From the years 2006 to 2019, the global inquiry for this term was highest (i.e., SVI at 100) last October 2018. There was a direct correlation between the SVI for "polio" and PC while there was an inverse relationship between SVI and VCR per country per year. Both relationships have weak to moderate strength of associations. Based on our models, a one-unit increase in the SVI leads to a 3.8% increase in the number of polio cases. On the other hand, a one-unit increase in the SVI leads to a 0.01% decrease in the VCR.Conclusions: Dynamic changes in global SVIs for polio may reflect fluctuations in the number of polio cases and rates of vaccine coverage. Our study brings into light the largely untapped and potential use of online search behavior for polio to anticipate changes in PC and VCR in real-time. What is Known: •Parental vaccine hesitancy is a strong hindrance to the eradication of vaccine-preventable diseases. •The internet is a major source of information that modifies this attitude. What is New: •Internet health-seeking behavior can be measured using Google Trends' search volume index and can be used to correlate to certain aspects of public health determinants of a certain disease. •Google Trends' search volume index correlates with the number of polio cases/immunization rates, and this provides a basis for considering public health measures online.

Role of Oral Rabies Vaccines in the Elimination of Dog-Mediated Human Rabies Deaths

Domestic dogs are responsible for nearly all the »59,000 global human rabies deaths that occur annually. Numerous control measures have been successful at eliminating dog-mediated human rabies deaths in upper-income countries, including dog population management, parenteral dog vaccination programs, access to human rabies vaccines, and education programs for bite prevention and wound treatment. Implementing these techniques in resource-poor settings can be challenging; perhaps the greatest challenge is maintaining adequate herd immunity in free-roaming dog populations. Oral rabies vaccines have been a cornerstone in rabies virus elimination from wildlife populations; however, oral vaccines have never been effectively used to control dog-mediated rabies. Here, we convey the perspectives of the World Organisation for Animal Health Rabies Reference Laboratory Directors, the World Organisation for Animal Health expert committee on dog rabies control, and World Health Organization regarding the role of oral vaccines for dogs. We also issue recommendations for overcoming hesitations to expedited field use of appropriate oral vaccines.

The Current State: Epidemiology and Working Toward Eradication

Acute polio, once epidemic and a significant source of paralysis and disability, has been dramatically reduced through global vaccination programs. Although vaccination efforts have experienced a setback because of COVID-19, resulting in increased number of vaccine-associated and wild virus infections, polio eradication is still a realistic goal that will result in significant cost savings. The secondary health issues related to aging with the residual effects of polio, including postpolio syndrome, will persist for many years posteradication. Continued education of medical professionals is essential to ensure provision of the necessary care to this population.

Bile Acids Impair Vaccine Response in Children With Biliary Atresia

Background

Vaccination is the best way to protect children under 5 years from death or disability. Children with biliary atresia (BA), which is the most common pediatric cholestatic end-stage liver disease (PELD), are more vulnerable to infectious diseases. However, the vaccination coverage and factors modulating vaccine responses in children with BA are largely unknown.

Methods

In this study, 288 children (median age: 7 months) diagnosed with BA before liver transplantation were enrolled for the evaluation of vaccination status and the factors affecting the immune response to the hepatitis B (HBV) vaccine. Moreover, 49 BA children (median age: 4 months) were enrolled for flow cytometric analysis of CD4⁺ T cells and CD19⁺ B cell subsets and correlations with serum bile acid levels.

Results

Generally, these children had very low routine vaccination rates for the meningococcal serogroup AC (Men AC) (41.2%), measles-mumps-rubella (MMR) (31.3%), poliomyelitis (Polio) (25.3%), hepatitis A (HAV) (25.0%), Japanese encephalitis (JE) (15.0%), diphtheria-tetanus-pertussis (DTP) (14.2%), meningococcal serogroup A (Men A) (13.5%) and varicella (VAR) (10.8%) vaccines, but not for the HBV (96.2%) and bacillus Calmette-Guérin (BCG) (84.7%) vaccines. Remarkably, 19.8% (57/288) of the patients had HBV infection. Out of 220 patients vaccinated for HBV, 113 (51.4%), 85 (38.6%) and 22 (10%) had one, two or three doses of the HBV vaccine, respectively. Furthermore, logistic regression analysis revealed that the bile acid level was an independent factor associated with poor HBV vaccine response (p = 0.03; OR = 0.394; 95% CI = 0.170-0.969). Immunophenotyping showed that bile acids were only negatively correlated with the CD19⁺CD27⁺IgG⁺ post-class-switched memory B cell ratio (p = 0.01).

Conclusion

This study reveals the overall vaccination rates of routine vaccines in Chinese BA children are very low and the poor HBV vaccine responses are associated with bile acids, possibly via the inhibition of CD19⁺CD27⁺IgG⁺ post-class-switched memory B cell response.

Clinical Trial Registration

http://www.chictr.org.cn, identifier ChiCTR1800019165.

Variability of in vivo potency tests of Diphtheria, Tetanus and acellular Pertussis (DTaP) vaccines

For batch release of legacy vaccines such as DTaP, in vivo potency release assays are required. We quantified the variability of in vivo potency release assays for four DTaP (Diphtheria, Tetanus, acellular Pertussis) products of different manufacturers. With their large CV (Coefficients of Variance) ranging from 16% to 132%, these in vivo assays are of limited value to ensure their potency is consistent and similar to the clinical batches used for the marketing authorisation. Our data show that, although individual potency test results show high variability, the DTaP batches are manufactured with great consistency, because repeated potency testing yields similar averages for the different batches. The economic impact of variability of in vivo tests is significant since it may result in the need for greater amount of antigen than may be required or for repeating a test. For monitoring the consistency of potency, in vitro assays are superior to in vivo assays. Animal-free potency determination is common practice for newly developed vaccines under modern GMP quality systems. However, replacement of in vivo potency tests for legacy vaccines like DTaP is challenging and would require a 'reverse characterisation' strategy in which the antigens are further characterised at the level of drug substance and drug product to identify critical quality attributes (CQA) that can be tested with in vitro assays. Based on these an updated set of release tests without animal tests can be proposed. Our data can serve as benchmark for the innovative methods.

Encapsulating Polyethyleneimine-DNA Nanoplexes into PEGylated Biodegradable Microparticles Increases Transgene Expression In Vitro and Reduces Inflammatory Responses In Vivo

Encapsulating genetic material into biocompatible polymeric microparticles is a means to improving gene transfection while simultaneously decreasing the tendency for inflammatory responses; and can be advantageous in terms of delivering material directly to the lungs via aerosolization for applications such as vaccinations. In this study, we investigated the advantages of using polymeric microparticles carrying the luciferase reporter gene in increasing transfection efficiency in the readily transfectable HEK293 cell line and the difficult to transfect RAW264.7 cell line. The results indicated that there was a limit to the ratio of nitrogen in polyethylenimine (PEI) to phosphate in DNA (N/P ratio) beyond which further increases in transgene expression no longer, or only marginally, occurred. Microparticles encapsulating PEI:DNA nanoplexes induced cellular toxicity in a dose-dependent manner. PEGylation increased transgene expression, likely related to enhanced degradation of particles. Furthermore, intra-tracheal instillation in rats allowed us to investigate the inflammatory response in the lung as a function of PEGylation, porosity, and size. Porosity did not influence cell counts in bronchoalveolar lavage fluid in the absence of PEG, but in particles containing PEG, non-porous particles recruited fewer inflammatory cells than their porous counterparts. Finally, both 1 μm and 10 μm porous PLA-PEG particles recruited more neutrophils than 4 μm particles. Thus, we have shown that PEGylation and lack of porosity are advantageous for faster release of genetic cargo from microparticles and a reduced inflammatory response, respectively.

Mammalian expression of virus-like particles as a proof of principle for next generation polio vaccines

Global vaccination programs using live-attenuated oral and inactivated polio vaccine (OPV and IPV) have almost eradicated poliovirus (PV) but these vaccines or their production pose significant risk in a polio-free world. Recombinant PV virus-like particles (VLPs), lacking the viral genome, represent safe next-generation vaccines, however their production requires optimisation. Here we present an efficient mammalian expression strategy producing good yields of wild-type PV VLPs for all three serotypes and a thermostabilised variant for PV3. Whilst the wild-type VLPs were predominantly in the non-native C-antigenic form, the thermostabilised PV3 VLPs adopted the native D-antigenic conformation eliciting neutralising antibody titres equivalent to the current IPV and were indistinguishable from natural empty particles by cryo-electron microscopy with a similar stabilising lipidic pocket-factor in the VP1 β-barrel. This factor may not be available in alternative expression systems, which may require synthetic pocket-binding factors. VLPs equivalent to these mammalian expressed thermostabilized particles, represent safer non-infectious vaccine candidates for the post-eradication era.

Advances in Oral Subunit Vaccine Design

Many pathogens invade the host at the intestinal surface. To protect against these enteropathogens, the induction of intestinal secretory IgA (SIgA) responses is paramount. While systemic vaccination provides strong systemic immune responses, oral vaccination is the most efficient way to trigger protective SIgA responses. However, the development of oral vaccines, especially oral subunit vaccines, is challenging due to mechanisms inherent to the gut. Oral vaccines need to survive the harsh environment in the gastrointestinal tract, characterized by low pH and intestinal proteases and need to reach the gut-associated lymphoid tissues, which are protected by chemical and physical barriers that prevent efficient uptake. Furthermore, they need to surmount default tolerogenic responses present in the gut, resulting in suppression of immunity or tolerance. Several strategies have been developed to tackle these hurdles, such as delivery systems that protect vaccine antigens from degradation, strong mucosal adjuvants that induce robust immune responses and targeting approaches that aim to selectively deliver vaccine antigens towards specific immune cell populations. In this review, we discuss recent advances in oral vaccine design to enable the induction of robust gut immunity and highlight that the development of next generation oral subunit vaccines will require approaches that combines these solutions.

Randomized Controlled Clinical Trial of bivalent Oral Poliovirus Vaccine and Inactivated Poliovirus Vaccine in Nigerian Children

BACKGROUND

We conducted a trial in Nigeria to assess the immunogenicity of the new bOPV + IPV immunization schedule and gains in type 2 immunity with addition of second dose of IPV. The trial was conducted in August 2016-March 2017 period, well past the tOPV-bOPV switch in April 2016.

METHODS

This was an open-label, two-arm, non-inferiority, multi-center, randomized controlled trial. We enrolled 572 infants of age ≤14 days and randomized them into two arms. Arm A received bOPV at birth, 6 and 10 weeks, bOPV+IPV at week 14 and IPV at week 18. Arm B received IPV each at 6, 10, 14 weeks and bOPV at 18 weeks of age.

RESULTS

Seroconversion rates for poliovirus types 1 and 3, respectively, were 98.9% (95%CI:96.7-99.8) and 98.1% (95%CI:88.2-94.8) in Arm A, and 89.6% (95%CI:85.4-93.0) and 98.5% (95%CI:96.3-99.6) in Arm B. Type 2 seroconversion with one dose IPV in Arm A was 72.0% (95%CI:66.2-77.3), which increased significantly with addition of second dose to 95.9% (95%CI:92.8-97.9).

CONCLUSION

This first trial on the new EPI schedule in a sub-Saharan African country demonstrated excellent immunogenicity against poliovirus types 1 and 3, and substantial/enhanced immunogenicity against poliovirus type 2 after 1 to 2 doses of IPV respectively.

The Risk of Bone Fractures in Post-Poliomyelitis Patients Transitioning to Middle Adulthood

ObjectiveWhile osteoporotic fractures are reported in up to 40% of adults with post-poliomyelitis syndrome (PPS), clinical guidelines regarding bone mineral density (BMD) and indications for treatment are scarce. We investigated the characteristics of PPS patients, focusing on fractures and osteoporosis as the primary outcomes.

METHODS

A cross-sectional retrospective data analysis from medical records of 204 PPS patients regarding their clinical characteristics and long-term outcome, with emphasis on bone metabolism status.

RESULTS

Our cohort included 53% women; mean age was 65 years at study entry and 1.7 years at the diagnosis of acute poliomyelitis. The lower limb was involved in 97.5% of patients, and the BMD in the affected limb tended to be lower than the unaffected, with a mean T-score of -1.64 vs. -1.19, respectively (P = .06). Recurrent falls were documented in 39.2% of patients, and osteoporosis in 20.6%, being more frequent in women (P = .003) and patients with fractures (P = .002). At least one fracture occurred in 52.2% of patients, and more than one in 40.3%. The median age for the first fracture was 57.5 years (range, 30 to 83 years), and most fractures occurred in the affected limb (73.2%).

CONCLUSIONS

Underdiagnosis and delayed treatment of osteoporosis in late-adulthood post-poliomyelitis patients underlie the need for comprehensive clinical guidelines to manage these patients, including recommendations on bone health assessment, medical treatment, and their inclusion as a high-risk group for bone fractures.

Vaccines as remedy for antimicrobial resistance and emerging infections

Life expectancy has grown tremendously. This incredible achievement for mankind has been obtained mostly thanks to three pillars: hygiene, antibiotics and vaccines. They represent one of the most effective forms of medical intervention. From Jenner's work to new vaccines, immunization has reduced the consequences of infectious diseases. In the last years antimicrobial resistance (AMR) as well as emerging infectious diseases have been rated as major threats for our society, as their toll is forecasted to drastically impinge on human health and economies. Indeed, recently, the whole world has experienced such problems because of the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of Covid-19. Herein, we propose an excursus through the three main pillars (hygiene, antibiotics and vaccination) that contributed to improving life expectancy, their clinical and economic impact and the role of vaccines to fight AMR-related diseases and emerging infectious diseases like Covid-19.

An epidemiological analysis of Acute Flaccid Paralysis (AFP) surveillance in Kenya, 2016 to 2018

Background

The poliovirus has been targeted for eradication since 1988. Kenya reported its last case of indigenous Wild Poliovirus (WPV) in 1984 but suffered from an outbreak of circulating Vaccine-derived Poliovirus type 2 (cVDPV2) in 2018. We aimed to describe Kenya’s polio surveillance performance 2016–2018 using WHO recommended polio surveillance standards.

Methods

Retrospective secondary data analysis was conducted using Kenyan AFP surveillance case-based database from 2016 to 2018. Analyses were carried out using Epi-Info statistical software (version 7) and mapping was done using Quantum Geographic Information System (GIS) (version 3.4.1).

Results

Kenya reported 1706 cases of AFP from 2016 to 2018. None of the cases were confirmed as poliomyelitis. However, 23 (1.35%) were classified as polio compatible. Children under 5 years accounted for 1085 (63.6%) cases, 937 (55.0%) cases were boys, and 1503 (88.1%) cases had received three or more doses of Oral Polio Vaccine (OPV). AFP detection rate substantially increased over the years; however, the prolonged health workers strike in 2017 negatively affected key surveillance activities. The mean Non-Polio (NP-AFP) rate during the study period was 2.87/ 100,000 children under 15 years, and two adequate specimens were collected for 1512 (88.6%) AFP cases. Cumulatively, 31 (66.0%) counties surpassed target for both WHO recommended AFP quality indicators.

Conclusions

The performance of Kenya’s AFP surveillance system surpassed the minimum WHO recommended targets for both non-polio AFP rate and stool adequacy during the period studied. In order to strengthen the country’s polio free status, health worker’s awareness on AFP surveillance and active case search should be strengthened in least performing counties to improve case detection. Similar analyses should be done at the sub-county level to uncover underperformance that might have been hidden by county level analysis.

Assessment of acute flaccid paralysis surveillance performance in East and Southern African countries 2012 - 2019

Introduction:

polio eradication initiatives started in 1988, this is almost the past 32 years following the WHA resolution 41.8 of eradicating polio by the year 2000. As of 2019, only 3 countries remained to be polio endemic globally, Afghanistan, Pakistan and Nigeria. The east and southern sub-region countries had shown progressive achievement towards polio eradication and to start with the African regional certification. The availability of sensitive AFP surveillance performance is among important strategies in the achievement of polio eradication. We, therefore, decided to conduct this assessment of AFP performance from 2012 to 2019 in the ESA sub-region have evidence documentation and support the certification process of the WHO AFRO region.

Methods:

we reviewed all reported acute flaccid paralysis (AFP) cases from 19 countries in the ESA sub region with the date of onset of paralysis from 1 January 2012 to 31 December 2019. The data were run to descriptive analysis based on the personal characteristics and AFP surveillance performance indicators parameters.

Results:

a total of 46,014 AFP cases were reported from 19 countries in the ESA countries who were paralyzed from 1 January 2012 to 31 December 2019. The most affected age group was children aged 0 to 3 years old where 19,740 children with acute paralysis were reported representing 42.9% of the total reported AFP for the period. The overall assessment of the non-polio AFP rate, there is an increase from a rate of 2.7 in 2012 to 3.5 in 2019 per 100,000 population aged less than 15 years, reflects a significant change with a p-value of 0.040 (95% C.I. ranges from 0.035 to 1.564). Furthermore, the percentage of stool adequacy raised from 86.4% in 2012 to 88.5% in 2019, with an observed 2.1% difference and no significant change over the 8 years.

Conclusion:

we observed an overall increase in the sensitivity of the AFP surveillance performance for the ESA sub-region countries from 2012 to 2019 using the national performance indicators. The COVID-19 pandemic paused an operational challenge for AFP surveillance performances from 2020. A further subnational surveillance performance analysis is suggested.

Environmental Surveillance Complements Case-Based Surveillance of Acute Flaccid Paralysis in Polio Endgame Strategy 2019-2023

The Polio Endgame Strategy 2019-2023 has been developed. However, more effective and efficient surveillance activities should be conducted with the preparedness of emergence for vaccine-derived poliovirus (VDPV) or wild poliovirus (WPV). We reviewed the impact of the case-based acute flaccid paralysis (AFP) surveillance (1991 to 2018) and environmental surveillance (2011 to 2018) in polio eradication in Shandong province of China. Clinical characteristics of AFP cases and enterovirus (EV) investigation of research samples were assessed. During the period, 10,224 AFP cases were investigated, and 352 sewage samples were collected. The nonpolio AFP rate sustained at over 2.0/100,000 since 1997. Of 10,224 cases, males and young children experienced a higher risk of severe diseases, and 68.5% suffered lower limb paralysis. We collected 1,707 EVs from AFP cases, including 763 polioviruses and 944 nonpolio enteroviruses (NPEVs). No WPV was isolated since 1992. The AFP surveillance showed high sensitivity in detecting 143 vaccine-associated paralytic poliomyelitis (VAPP) cases and 6 VDPVs. For environmental surveillance, 217 (61.6%) samples were positive for poliovirus, and altogether, 838 polioviruses and 2,988 NPEVs were isolated. No WPV was isolated in environmental surveillance, although one VDPV2 was identified. Phylogenetic analysis revealed environmental surveillance had the capacity to detect a large scope of NPEVs. The case-based AFP surveillance will be indispensable for detecting VAPP cases and VDPV circulation in countries using oral polio vaccine. Environmental surveillance is advantageous in identifying EV circulation and responding to ongoing circulating VDPV outbreaks and should be expanded to complement the AFP surveillance.IMPORTANCE Interrupting wild poliovirus transmission and stopping circulating vaccine-derived poliovirus (cVDPV) outbreaks have been proposed as two global goals by the World Health Organization in the Global Polio Eradication Initiative (GPEI). This analysis, based on the 28-year acute flaccid paralysis (AFP) surveillance and 8-year environmental surveillance, provides continued high-quality surveillance performance in achieving the GPEI and detecting the circulation of enterovirus. Given the ongoing cVDPV outbreaks in the world, we present the surveillance capacity of environmental surveillance in capturing enterovirus circulation. The final poliovirus (especially VDPV) elimination has become increasingly complex, and the case-based AFP surveillance alone will lead to difficulties in early detecting dynamics of poliovirus transmission and monitoring the extent of environmental circulation. This study goes beyond previous work to provide a detailed comprehensive evaluation of the enterovirus surveillance and can be used to formulate a set of implementation plan and performance indicators for environmental surveillance.

Progress Toward Polio Eradication - Worldwide, January 2018-March 2020

Since the Global Polio Eradication Initiative (GPEI) was established in 1988, two of the three wild poliovirus (WPV) serotypes (types 2 and 3) have been eradicated.* Transmission of WPV type 1 (WPV1) remains uninterrupted only in Afghanistan and Pakistan. This report summarizes progress toward global polio eradication during January 1, 2018-March 31, 2020 and updates previous reports (1,2). In 2019, Afghanistan and Pakistan reported the highest number of WPV1 cases (176) since 2014. During January 1-March 31, 2020 (as of June 19), 54 WPV1 cases were reported, an approximate fourfold increase from 12 cases during the corresponding period in 2019. Paralytic poliomyelitis can also be caused by circulating vaccine-derived poliovirus (cVDPV), which emerges when attenuated oral poliovirus vaccine (OPV) virus reverts to neurovirulence following prolonged circulation in underimmunized populations (3). Since the global withdrawal of type 2-containing OPV (OPV2) in April 2016, cVDPV type 2 (cVDPV2) outbreaks have increased in number and geographic extent (4). During January 2018-March 2020, 21 countries reported 547 cVDPV2 cases. Complicating increased poliovirus transmission during 2020, the coronavirus disease 2019 (COVID-19) pandemic and mitigation efforts have resulted in suspension of immunization activities and disruptions to poliovirus surveillance. When the COVID-19 emergency subsides, enhanced support will be needed to resume polio eradication field activities.

Surveillance to Track Progress Toward Polio Eradication - Worldwide, 2018-2019

Since the Global Polio Eradication Initiative (GPEI) was launched in 1988, the number of polio cases worldwide has declined approximately 99.99%; only two countries (Afghanistan and Pakistan) have never interrupted wild poliovirus (WPV) transmission (1). The primary means of detecting poliovirus circulation is through surveillance for acute flaccid paralysis (AFP) among children aged <15 years with testing of stool specimens for WPV and vaccine-derived polioviruses (VDPVs) (genetically reverted strains of the vaccine virus that regain neurovirulence) in World Health Organization (WHO)-accredited laboratories (2,3). In many locations, AFP surveillance is supplemented by environmental surveillance, the regular collection and testing of sewage to provide awareness of the extent and duration of poliovirus circulation (3). This report presents 2018-2019 poliovirus surveillance data, focusing on 40 priority countries* with WPV or VDPV outbreaks or at high risk for importation because of their proximity to a country with an outbreak. The number of priority countries rose from 31 in 2018 to 40 in 2019 because of a substantial increase in the number of VDPV outbreaks^† (2,4). In areas with low poliovirus immunity, VDPVs can circulate in the community and cause outbreaks of paralysis; these are known as circulating vaccine derived polioviruses (cVDPVs) (4). In 2019, only 25 (63%) of the 40 designated priority countries met AFP surveillance indicators nationally; subnational surveillance performance varied widely and indicated focal weaknesses. High quality, sensitive surveillance is important to ensure timely detection and response to cVDPV and WPV transmission.

The role of genetic sequencing and analysis in the polio eradication programme

Genetic sequencing of polioviruses detected through clinical and environmental surveillance is used to confirm detection, identify their likely origin, track geographic patterns of spread, and determine the appropriate vaccination response. The critical importance of genetic sequencing and analysis to the Global Polio Eradication Initiative has grown with the increasing incidence of vaccine-derived poliovirus (VDPV) infections in Africa specifically (470 reported cases in 2019), and globally, alongside persistent transmission of serotype 1 wild-type poliovirus in Pakistan and Afghanistan (197 reported cases in 2019). Adapting what has been learned about the virus genetics and evolution to address these threats has been a major focus of recent work. Here, we review how phylogenetic and phylogeographic methods have been used to trace the spread of wild-type polioviruses and identify the likely origins of VDPVs. We highlight the analysis methods and sequencing technology currently used and the potential for new technologies to speed up poliovirus detection and the interpretation of genetic data. At a pivotal point in the eradication campaign with the threat of anti-vaccine sentiment and donor and public fatigue, innovation is critical to maintain drive and overcome the last remaining circulating virus.

Valuing the cost of improving Chilean primary vaccination: a cost minimization analysis of a hexavalent vaccine

BACKGROUND

The phased withdrawal of oral polio vaccine (OPV) and the introduction of inactivated poliovirus vaccine (IPV) is central to the polio 'end-game' strategy.

METHODS

We analyzed the cost implications in Chile of a switch from the vaccination scheme consisting of a pentavalent vaccine with whole-cell pertussis component (wP) plus IPV/OPV vaccines to a scheme with a hexavalent vaccine with acellular pertussis component (aP) and IPV (Hexaxim®) from a societal perspective. Cost data were collected from a variety of sources including national estimates and previous vaccine studies. All costs were expressed in 2017 prices (US$ 1.00 = $Ch 666.26).

RESULTS

The overall costs associated with the vaccination scheme (4 doses of pentavalent vaccine plus 1 dose IPV and 3 doses OPV) from a societal perspective was estimated to be US$ 12.70 million, of which US$ 8.84 million were associated with the management of adverse events related to wP. In comparison, the cost associated with the 4-dose scheme with a hexavalent vaccine (based upon the PAHO reference price) was US$ 19.76 million. The cost of switching to the hexavalent vaccine would be an additional US$ 6.45 million. Overall, depending on the scenario, the costs of switching to the hexavalent scheme would range from an additional US$ 2.62 million to US$ 6.45 million compared with the current vaccination scheme.

CONCLUSIONS

The switch to the hexavalent vaccine schedule in Chile would lead to additional acquisition costs, which would be partially offset by improved logistics, and a reduction in adverse events associated with the current vaccines.

Development of a new oral poliovirus vaccine for the eradication end game using codon deoptimization

Enormous progress has been made in global efforts to eradicate poliovirus, using live-attenuated Sabin oral poliovirus vaccine (OPV). However, as the incidence of disease due to wild poliovirus has declined, vaccine-derived poliovirus (VDPV) has emerged in areas of low-vaccine coverage. Coordinated global cessation of routine, type 2 Sabin OPV (OPV2) use has not resulted in fewer VDPV outbreaks, and continued OPV use in outbreak-response campaigns has seeded new emergences in low-coverage areas. The limitations of existing vaccines and current eradication challenges warranted development of more genetically stable OPV strains, most urgently for OPV2. Here, we report using codon deoptimization to further attenuate Sabin OPV2 by changing preferred codons across the capsid to non-preferred, synonymous codons. Additional modifications to the 5′ untranslated region stabilized known virulence determinants. Testing of this codon-deoptimized new OPV2 candidate (nOPV2-CD) in cell and animal models demonstrated that nOPV2-CD is highly attenuated, grows sufficiently for vaccine manufacture, is antigenically indistinguishable from Sabin OPV2, induces neutralizing antibodies as effectively as Sabin OPV2, and unlike Sabin OPV2 is genetically stable and maintains an attenuation phenotype. In-human clinical trials of nOPV2-CD are ongoing, with potential for nOPV strains to serve as critical vaccine tools for achieving and maintaining polio eradication.

Wild Poliovirus Type 1 in Oman: A re-emerging threat that requires urgent, targeted and strategic preparedness

Poliomyelitis, also known as polio, is a highly infectious viral disease, predominantly affecting children under five years old. The virus is transmitted from person-to-person and mainly spreads through the fecal-oral route. The virus multiplies in the intestine, from where it can invade the nervous system via the bloodstream, potentially causing paralysis. Polio symptoms include fever, fatigue, headache, vomiting, neck stiffness and pain in the limbs. The disease causes permanent paralysis in one out of 200 infections. Currently, there is no cure for polio; it can only be prevented by immunisation.1

Molecular Characterization and Clinical Description of Non-Polio Enteroviruses Detected in Stool Samples from HIV-Positive and HIV-Negative Adults in Ghana

In the post-polio eradication era, increasing attention is given to non-polio enteroviruses. Most of the data about enteroviruses in sub-Saharan Africa are related to acute flaccid paralysis surveillance and target the pediatric population. This study aimed to investigate the presence of enterovirus in PLHIV (people living with HIV) and HIV-negative individuals in Ghana. Stool samples from HIV-positive individuals (n = 250) and healthy blood donors (n = 102) attending the Komfo Anokye Teaching Hospital in Kumasi, Ghana, were screened by real-time PCR for enterovirus. Molecular typing of the VP1 region was performed. Enterovirus-positive samples were tested for norovirus, adenovirus, rotavirus, sapovirus, and cosaviruses. Twenty-six out of 250 HIV-positive subjects (10.4%) and 14 out of 102 HIV-negative individuals (13.7%) were detected enterovirus-positive, not showing a significant different infection rate between the two groups. HIV-negative individuals were infected with Enterovirus C strains only. HIV-positive participants were detected positive for species Enterovirus A, Enterovirus B, and Enterovirus C. Co-infections with other viral enteric pathogens were almost exclusively detected among HIV-positive participants. Overall, the present study provides the first data about enteroviruses within HIV-positive and HIV-negative adults living in Ghana.

A erradicação da poliomielite em quatro tempos

O objetivo deste artigo é rever o “estado da arte” dos avanços, obstáculos e estratégias para atingir a erradicação global da pólio. As ações de controle da poliomielite iniciaram na década de 1960 com o advento das duas vacinas antipoliomielíticas, a vacina oral da pólio (VOP) e a vacina inativada da pólio (VIP). No período de 1985 a 2020, são implementadas estratégias para atingir a meta de erradicação do poliovírus selvagem (WPV). Após o sucesso da interrupção da transmissão autóctone do WPV na região da Américas, foi lançada a meta da erradicação global. Descrevemos o processo de erradicação em quatro tempos: (1) O advento das vacinas VIP e VOP iniciou a era do controle da poliomielite; (2) A utilização massiva e simultânea da VOP teve impacto significativo sobre a transmissão do poliovírus selvagem no final da década de 1970 no Brasil; (3) Políticas públicas (nacionais e internacionais) decidem pela erradicação da transmissão autóctone do poliovírus selvagem nas Américas e definem as estratégias epidemiológicas para interromper a transmissão; e (4) A implantação das estratégias de erradicação interrompeu a transmissão autóctone do WPV em quase todas as regiões do mundo, exceto no Paquistão e Afeganistão, onde, em 2020, cadeias de transmissão do WPV1 desafiam as estratégias de contenção do vírus. Por outro lado, a persistência e a disseminação da circulação do poliovírus derivado da VOP, em países com baixa cobertura vacinal, somadas às dificuldades para substituir a VOP pela VIP constituem, atualmente, os obstáculos para a erradicação a curto prazo. Finalmente, discutimos as estratégias para superar os obstáculos e os desafios na era pós-erradicação.