Polio Vaccine Research Articles

Influence of trust on the acceptance of the RTS,S malaria vaccine in the Kassena-Nankana districts of Ghana

BackgroundVaccines have increasingly become some of the most effective public health tools for promoting health and reducing the burden of infectious diseases. The availability of a malaria vaccine for routine use will be a major milestone, nonetheless, trust by the public for the vaccine could pose a major challenge for its acceptance. Documented evidence such as the boycott of the oral polio vaccine in northern Nigeria and the failure of the Ebola vaccine trial in Ghana among others highlight the impact of public trust on vaccine acceptance.MethodsThis is an explorative cross-sectional mixed-method study conducted in the Kassena Nankana districts. The study was conducted in the Kassena Nankana Districts between May and December 2020. A total of 390 structured questionnaires were administrated to mothers and caregivers of children under five years of age while 15 in-depth interviews were conducted with mothers and health workers. STATA software Version 16.0 was used to interpret the quantitative data, where bivariate and multivariate regression analysis was performed to determine the influence of trust on vaccine acceptance while QSR NVivo 12 software was used to code the qualitative data to aid the thematic analysis.ResultsThe results revealed that the level of knowledge of the RTS,S vaccine among participants was high. About 95.4% of the mothers had good knowledge of the malaria vaccine and more than half 61.2% of them got information about the vaccine from the health facility. The level of trust for the malaria vaccine was equally high with 91.4% of the mothers reporting that the vaccine treats childhood malaria. In a bivariate analysis, educational status (P = 0.013), ethnicity (P = 0.008), marital status (P = 0.041), education on the vaccine and perceived ineffectiveness P < 0.05, and trust for the malaria vaccine (P < 0.05) were found to be statistically associated with vaccine acceptance. Compared with participants who agree that vaccines are harmless to children, those who disagree were significantly less likely to accept vaccines (OR = 0.25, 95%CI [0.08, 0.83], p = 0.017). The qualitative data correspondingly revealed that mothers trusted vaccines which thus accounted for the high uptake of the malaria vaccine in the districts.ConclusionThe results of this study suggest that trust in the malaria vaccine is critical for its uptake. Therefore, efforts towards improving acceptance of the vaccine should be focused on building and sustaining trust for the vaccine among mothers and community members.

Polio Epidemiology: Strategies and Challenges for Polio Eradication Post the COVID-19 Pandemic

The Global Polio Eradication Initiative (GPEI), launched in 1988, has successfully reduced wild poliovirus (WPV) cases by over 99.9%, with WPV type 2 and WPV3 declared eradicated in 2015 and 2019, respectively. However, as of 2024, WPV1 remains endemic in Afghanistan and Pakistan. Since 2000, outbreaks of circulating virus derived of polio vaccines (cVDPVs) have emerged in multiple regions, primary driven by low vaccine coverage rates (VCRs). The COVID-19 pandemic disrupted routine immunization, resulting in millions of unvaccinated children, and leaving many countries vulnerable to both WPV1 and cVDPVs outbreaks. This paper reviews the epidemiological landscape of poliomyelitis post the COVID-19 pandemic, and the strategies and challenges to achieve the global polio eradication.

The importance of quality of health campaign information for outcome evaluation. A case study from Guinea-Bissau and Bangladesh

BackgroundNumerous national health intervention campaigns, e.g. supplementary immunization campaigns/activities (SIAs), have been conducted in low- and middle-income countries (LMIC) in the last decades. These campaigns are rarely evaluated for overall health outcomes. Information on campaigns is critical for evaluations. We investigated; 1) quality of campaign information sources and 2) implication of quality for outcome evaluations. MethodsWe focused on three campaign types: oral polio vaccine (OPV), vitamin A supplementation (VAS) and measles vaccine (MV) campaigns in two case countries, for which “gold standard” information on campaigns collected regularly at Health and Demographic Surveillance Systems (HDSS) sites: Guinea-Bissau and Bangladesh. We compared the campaign information from HDSS with information from the World Health Organisation (WHO) and the Rotary Foundation (Rotary, only OPV campaigns). First, campaigns were matched and compared based on intervention type, date of campaign and target age group. Second, we assessed the implications of using various sources of campaign information on the estimated effect of OPV campaigns on all-cause under-3-year mortality in Cox proportional hazards regression models. ResultsThe proportion of matched OPV campaigns was highest between HDSS and Rotary. VAS campaigns (only information from HDSS and WHO) matched poorly. The estimated effect of OPV campaigns information on child mortality in Bangladesh went from being statistically significant (HR = 0.69 (0.52–0.90)) using HDSS campaign information to not being significant (HR = 0.93 (0.71–1.21) using WHO campaign information. ConclusionCompared with the HDSS, Rotary had the best campaign information on the conduct of OPV campaigns, whereas the WHO quality of campaign information was low for both OPV and VAS. A low quality of campaign information may alter conclusions of health outcome evaluations. Reliable and precise information on campaigns is essential to assess their effects. Public and private campaign stakeholders should track campaign information meticulously and support that publicly data is available for researchers.

Cost of the typhoid conjugate vaccine introduction through an integrated campaign and follow-on routine immunization in Malawi

Malawi introduced typhoid conjugate vaccine (TCV) in 2023 through an integrated campaign delivering TCV alongside other vaccines and interventions (measles rubella vaccine (MRV), bivalent oral polio vaccine (OPV), and vitamin A Supplementation). The campaign sought to reach all children 9 months to younger than 14 years, representing more than 9 million individuals, and about half the country’s population. Following the campaign, TCV was incorporated into the routine immunization program for 9-month-old infants. We conducted a micro-costing study at 50 randomly selected health facilities, 10 districts, and at national level to retrospectively assess the financial and economic cost of the integrated campaign, as well as prospectively estimate the cost of delivering TCV in the routine immunization system. The financial and economic costs per dose for all interventions delivered in the campaign were $0.49 ($0.42;$0.57) and $0.84 ($0.67;$1.02), respectively. The main activities and cost types varied; human resources represented the main resource at health facility level, and per diem at district and national levels. The financial and economic cost to routinely deliver a dose of TCV were $0.44 ($0.17;$0.87), and $2.37 ($1.39;$3.53), respectively, with human resources as the main resource used by the routine program at all levels.The cost per dose delivered in the integrated campaign in Malawi was comparable with other integrated campaigns and was lower than the reported cost to deliver TCV in single antigen campaigns in India and Zimbabwe. Integrated campaigns may represent an opportunity to introduce new vaccines such as TCV to lower the cost per dose delivered. Attention should be given to challenges coming with integration, such as the burden for healthcare workers.Evidence produced by this study can be used in Malawi to inform financial sustainability of the TCV program and should inform decisions and strategies for implementation by other countries.

Antisera-Neutralizing Capacity of a Highly Evolved Type 2 Vaccine-Derived Poliovirus from an Immunodeficient Patient.

The serotype 2 oral poliovirus vaccine (OPV2) can revert to regain wild-type neurovirulence and spread, causing the emergence of vaccine-derived poliovirus (VDPV2) and immunodeficiency-related vaccine-derived polioviruses (iVDPVs). In the United States, testing carried out by the CDC of type II iVDPV (iVDPV2) with human immune serum from the vaccine has shown that the presence of the virus poses a threat to eradication efforts. We analyzed the major neutralization sites of VP1, VP2, and VP3 of the iVDPV using bioinformatics techniques and homology modeling (SWISS-MODEL). The three amino acid residues 679, 680, and 141 of the P1 region changed, which had an impact on the spatial conformation of the viral-neutralizing site. We tested polio-vaccinated human sera and rabbit anti-Sabin II polyantibodies against a panel of iVDPV pseudoviruses. The results demonstrated that the serum's capacity to neutralize mutant pseudoviruses diminished when amino acid substitutions were introduced into the P1 encapsidated protein, particularly when 141 and 679 were mutated together. This study emphasizes the significance of continually monitoring individuals who are known to be immunocompromised and maintaining high vaccination rates in OPV-using communities.

Analysis of the current status of the protection in children from of polio

Introduction. There is a risk of an exponential increase in the incidence of polio in the world, if there is a deviation from the current plan of measures to localize endemic areas of polio and until global eradication of the virus achieved. Routine immunization against polio and widespread vaccination is the main goal of the polio control strategy. There is currently no need to strengthen planned vaccination work in Russia to consolidate the results of the polio control program, as evidenced by the data of dynamic serological monitoring. Aim: Evaluate the level of seroconversion after administration of poliovaccine and the duration of protective antibody titer maintenance in children. Materials and methods. A single-stage, single-center determination of the titer of antibodies to poliovirus types 1 and 3 was carried out using the neutralization method. There were studied 162 samples collected as part of the assignment from the Center of Hygiene and Epidemiology of the Republic of Buryatia (1.44% of the pediatric population of the children’s polyclinic): three groups of 1–2 years, 3–4 years and 15–17 years children. The average age in the group 1 was 1.64 ± 0.48 years, group 2 — 3.48 ± 0.54 years, and group 3 — 15.38 ± 0.67 years. Medical documentation was analyzed and compared: completed preventive vaccination cards (form 063/u) and preventive vaccination sheet in the child development card (form 112/u) for a complete collection children’s vaccination history. Results. Deviations of vaccination dates from the current national calendar of preventive vaccinations noted in all age groups with a high frequency. In our analysis, 100% of children demonstrate the presence of protective antibodies to poliomyelitis types 1 and 3. The duration of preservation of neutralizing antibodies is 13.05 ± 0.94 years, with an average of 9–15 years. Conclusion. The analyzed serological monitoring of postvaccinal immunity to poliomyelitis testifies to the high efficiency of the preventive work.

Evaluation of the Intensive Acute Flaccid Paralysis Surveillance System in Ghana: Post the Switch from tOPV to bOPV.

The Global Polio Eradication Initiative was adopted by Ghana in 1996, and through robust AFP surveillance was able to interrupt the circulation of wild poliovirus in 2008. However, the country suffered vaccine-derived poliovirus type 2 outbreaks in 2019 and 2022. We conducted a retrospective analysis of all AFP surveillance data received by the polio program in Ghana from 2018 to 2022. An analysis of the WHO performance indicators for evaluating a surveillance system was conducted using Epi Info 3.5.4 and Microsoft Excel. Of the 4832 cases investigated, 56.3% were males, 71.1% comprised children aged 5 years and below, and more than half (65.2%) had received a maximum of three doses of OPV. Over 77% (3028) had a fever at the onset of paralysis, and 67.8% had paralysis progression within 3 days. The non-polio AFP rate of ≥2 and the stool adequacy rate exceeded the target of ≥80% in nearly every study year. The proportion of non-polio enteroviruses isolated surpassed the target of ≥10% in all years except 2018. The AFP surveillance system in Ghana is sensitive and representative. Though the surveillance became more intensive and proactive during the outbreak, the system needs to focus on improving the completeness of the data as well as the timeliness of the arrival of stool specimens within 3 days of collection.

Detection of circulating type 3 vaccine-derived polioviruses in French Guiana, May to August 2024.

Circulating type 3 vaccine-derived polioviruses (cVDPV3s) were detected in three wastewater samples collected in French Guiana from May through August 2024. As the oral polio vaccine is not used in French Guiana, this event involved an import either of cVDPV3s themselves or of a vaccine strain from which the cVDPV3s emerged in French Guiana. This highlights the importance of environmental surveillance for the detection of silent poliovirus circulation. Eliminating any pockets of cVDPVs is crucial for the polio eradication programme.

Antiviral Development for the Polio Endgame: Current Progress and Future Directions.

As the world is approaching the eradication of wild poliovirus serotype 1, the last of the three wild types, the question of how to maintain a polio-free world becomes imminent. To mitigate the risk of sporadic vaccine-associated paralytic polio (VAPP) caused by oral polio vaccines (OPVs) that are routinely used in global immunization programs, the Polio Antivirals Initiative (PAI) was established in 2006. The primary goal of the PAI is to facilitate the discovery and development of antiviral drugs to stop the excretion of immunodeficiency-associated vaccine-derived poliovirus (iVDPV) in B cell-deficient individuals. This review summarizes the major progress that has been made in the development of safe and effective poliovirus antivirals and highlights the candidates that have shown promising results in vitro, in vivo, and in clinical trials.

Polio Disease and Immunization: Knowledge and Attitude of Filipino Mothers in a Rural Community

Background: In response to the 2019 Polio outbreak in the Philippines, it is crucial to examine the current understanding and beliefs about the disease. This study assessed the knowledge and attitudes of mothers towards Polio and Polio vaccination in a rural community. Materials and Methods: Sixty-two mothers in a selected rural barangay in Negros Occidental, Philippines, participated in this cross-sectional study using a survey questionnaire in July 2021. Descriptive statistics and correlation analysis were employed. Results: The results showed that 43.50% of mothers had a high level of knowledge and 74.20% had a favorable attitude towards Polio and Polio immunization. There was a significant relationship (p = 0.05) between knowledge and attitude towards Polio and Polio immunization. Conclusions: This study underscores addressing knowledge gaps through public health campaigns may improve beliefs and perceptions about immunization programs.

Wastewater Surveillance for Poliovirus in Selected Jurisdictions, United States, 2022-2023.

Wastewater testing can inform public health action as a component of polio outbreak response. During 2022-2023, a total of 7 US jurisdictions (5 states and 2 cities) participated in prospective or retrospective testing of wastewater for poliovirus after a paralytic polio case was identified in New York state. Two distinct vaccine-derived poliovirus type 2 viruses were detected in wastewater from New York state and New York City during 2022, representing 2 separate importation events. Of those viruses, 1 resulted in persistent community transmission in multiple New York counties and 1 paralytic case. No poliovirus was detected in the other participating jurisdictions (Connecticut, New Jersey, Michigan, and Illinois and Chicago, IL). The value of routine wastewater surveillance for poliovirus apart from an outbreak is unclear. However, these results highlight the ongoing risk for poliovirus importations into the United States and the need to identify undervaccinated communities and increase vaccination coverage to prevent paralytic polio.

Cost of integrated immunization campaigns in Nigeria and Sierra Leone: bottom-up costing studies

BackgroundTo improve the efficient use of scarce resources, low- and middle-income countries and development partners are increasingly encouraged to deliver multiple vaccines and other interventions in a single integrated campaign. However, little is known regarding the cost of delivering vaccines through integrated campaigns, and the extent to which efficiencies are achieved. To fill this evidence gap, we estimated the cost of integrated immunization campaigns in Nigeria and Sierra Leone, and the potential savings from integration.MethodsWe conducted a retrospective ingredients-based costing study from a payer perspective of a campaign held in 2019 in Sierra Leone with measles-rubella vaccine and oral polio vaccine, during which nutrition supplements were also offered in part of the country, and yellow fever campaigns held in three states in Nigeria in 2019 and 2020, where in one state (Anambra) meningococcal A vaccines were co-delivered. We collected data from 108 health facilities, all relevant administrative levels, and implementing partners. We estimated the full financial and economic cost of each campaign, the average unit cost of delivery, as well as the cost by activity and resource type. We also estimated the cost savings from integration in Anambra state by modelling out the cost of the alternative of two standalone campaigns.ResultsThe average financial delivery cost was $0.34 per dose in Sierra Leone, and the economic cost was $0.73 per dose. In Nigeria, the financial cost per dose was $0.29–$0.35 across the three states, and the economic cost per dose was $0.62–$0.85. Facilities and wards delivering more doses achieved a lower financial and economic unit cost of delivery, demonstrating evidence of economies of scale. We estimated that Anambra may have saved at least $1,204,133 in financial resources by integrating yellow fever and meningitis A vaccine delivery, amounting to $0.17 per dose delivered. When including opportunity costs, the economic cost saving was estimated at $0.34 per dose delivered.ConclusionsThe study offers evidence on what it costs to deliver integrated campaigns, and shows that integrated delivery is likely to result in significant cost savings. Where high delivery volumes can be achieved, integrated campaigns can benefit from economies of scale. The findings can be used to inform planning and budgeting for immunization campaigns in low- and middle-income countries.

Complete genome sequences of nine double recombinant vaccine-derived novel oral poliovirus type 2 genomes from Nigeria 2023-2024.

We report the complete genome sequences of nine double recombinant vaccine-derived novel oral poliovirus type 2 genomes from acute flaccid paralysis (AFP) cases (n = 3), AFP case contacts (n = 4), and environmental surveillance sampling (n = 2) in Nigeria.

Optimizing vaccination to reduce waste and boost coverage in Primary Health Care Units

Abstract Background In immunization, vaccine consumption typically exceeds the number of recipients. The number of doses per vial influences wastage and vaccination coverage goals. In Brazil, 48% of the National Immunization Program’s vaccines are multidose, with 4 having limited shelf-life post-opening. Strategies to reduce wastage aim to optimize dose utilization, enhance process quality, and broaden coverage effectiveness. The objective was to outline strategies for reducing wastage and expanding coverage for children under 5 in 14 São Paulo city Primary Health Care Units (PHCUs). Methods The Lean Six Sigma approach guided the stages. A group conducted contextual analysis to identify PHCU barriers. Data on wasted doses and vaccination were gathered. Weekly meetings for data analysis began in May 2023, following DMAIC phases: Define, Measure, Analyze, Improve, Control. An action plan stemmed from these phases for PHCU implementation. Results Data analysis, from January 2022 to June 2023, revealed a significant vaccine wastage trend, reaching 59% from January to December 2022 and increasing to 63% from January to June 2023. This wastage incurs an average annual cost of R$614,416.26, due to lost doses from expiration after vial opening and expiration of shelf life. The vaccines analyzed were BCG, Oral Polio Vaccine (OPV), Measles, Mumps, and Rubella (MMR), and Yellow Fever. At the project start in May 2023, vaccination coverage was 90%, increasing to 93% afterward. This rise resulted from actions taken and improved data monitoring. Post-project, vaccine wastage reduced by 7 percentage points (from 62% to 56%). Conclusions Addressing vaccine wastage and expanding vaccination coverage for children under 5 are critical in healthcare. Utilizing Lean Six Sigma, key issues in PHCUs were identified, leading to an action plan that reduced wastage, increased coverage, and standardized processes. Key messages • Vaccines are valuable resources and wasting them means reducing financial resources in health. • Vaccination coverage is crucial to protect the population’s health, prevent disease outbreaks, and maintain the country’s economic health, reducing costs for treating preventable diseases.

Coverage with Selected Vaccines and Exemption Rates Among Children in Kindergarten - United States, 2023-24 School Year.

In the United States, states and local jurisdictions set vaccination requirements for school attendance, conditions and procedures for exemptions from these requirements, grace periods for submitting documentation, and provisional enrollment for students who need more time to be vaccinated. States annually report data to CDC on the number of children in kindergarten who meet, are exempt from, or are in the process of meeting requirements. Data reported by 49 states and the District of Columbia (DC) for the 2023-24 school year were used for national- and state-level estimates of the following measures: complete vaccination with required doses of measles, mumps, and rubella vaccine (MMR), diphtheria, tetanus, and acellular pertussis vaccine (DTaP), poliovirus vaccine (polio), and varicella vaccine (VAR); exemptions from vaccination; and school attendance while meeting requirements. The 2023-24 kindergarten class became age-eligible to complete most state-required vaccinations during the COVID-19 pandemic, after schools had returned to routine in-person learning. Compared with approximated national coverage levels across all reported vaccines for the 2019-20 (95%) and 2022-23 (93%) school years, coverage dropped below 93% for the 2023-24 school year, ranging from 92.3% for DTaP to 92.7% for MMR. Exemptions increased to 3.3%, compared with those during the 2022-23 (3.0%) and 2021-22 school years (2.6%). Coverage with MMR, DTaP, polio, and VAR decreased in 35, 32, 33, and 36 jurisdictions, respectively, compared with the 2022-23 school year. Exemptions increased in 41 jurisdictions, with 14 reporting that >5% of kindergartners had an exemption from one or more vaccine. Efforts by health departments, schools, and providers are needed to ensure that students begin school fully vaccinated.

Update on Vaccine-Derived Poliovirus Outbreaks - Worldwide, January 2023-June 2024.

Circulating vaccine-derived polioviruses (cVDPVs) can emerge and lead to outbreaks of paralytic polio as well as asymptomatic transmission in communities with a high percentage of undervaccinated children. Using data from the World Health Organization Polio Information System and Global Polio Laboratory Network, this report describes global polio outbreaks due to cVDPVs during January 2023-June 2024 and updates previous reports. During the reporting period, 74 cVDPV outbreaks were detected in 39 countries or areas (countries), predominantly in Africa. Among these 74 cVDPV outbreaks, 47 (64%) were new outbreaks, detected in 30 (77%) of the 39 countries. Three countries reported cVDPV type 1 (cVDPV1) outbreaks and 38 countries reported cVDPV type 2 (cVDPV2) outbreaks; two of these countries reported cocirculating cVDPV1 and cVDPV2. In the 38 countries with cVDPV2 transmission, 70 distinct outbreaks were reported. In 15 countries, cVDPV transmission has lasted >1 year into 2024. In Nigeria and Somalia, both countries with security-compromised areas, persistent cVDPV2 transmission has spread to neighboring countries. Delayed implementation of outbreak response campaigns and low-quality campaigns have resulted in further international spread. Countries can control cVDPV outbreaks with timely allocation of resources to implement prompt, high-quality responses after outbreak confirmation. Stopping all cVDPV transmission requires effectively increasing population immunity by overcoming barriers to reaching children.

Introduction of a hexavalent vaccine containing acellular pertussis into the national immunization program for infants in Peru: a cost-consequence analysis of vaccination coverage

BackgroundInfant vaccination coverage rates in Peru have declined in recent years, exacerbated by the COVID-19 pandemic. Introduction of the fully-liquid diphtheria, tetanus, and acellular pertussis (DTaP)-inactivated polio vaccine (IPV)-hepatitis B (HB)-Haemophilus influenzae type B (Hib) hexavalent vaccine (DTaP-IPV-HB-Hib) in Peru’s infant National Immunization Program may help improve coverage. We evaluated costs and healthcare outcomes, including coverage, of switching from a pentavalent vaccine containing whole-cell pertussis component (DTwP-HB-Hib) plus IPV/oral polio vaccine (IPV/OPV) to the hexavalent vaccine for the primary vaccination scheme (2, 4 and 6 months).MethodsThe analysis was performed over a 5-year period on a cohort of children born in Peru in 2020 (N = 494,595). Four scenarios were considered: the pentavalent plus IPV/OPV scheme (S1); replacing the pentavalent plus IPV/OPV scheme with the hexavalent scheme (S2); expanded delivery of the pentavalent plus IPV/OPV scheme (S3); expanded delivery of the hexavalent scheme (S4). Vaccine coverage and incidence of adverse reactions (ARs) were estimated using Monte Carlo simulations and previous estimates from the literature. Cases of vaccine-preventable diseases were estimated using a Markov model. Logistical and healthcare costs associated with these outcomes were estimated. Impact of key variables (including coverage rates, incidence of ARs and vaccine prices) on costs was evaluated in sensitivity analyses.ResultsThe overall cost from a public health payer perspective associated with the pentavalent plus IPV/OPV vaccine scheme (S1) was estimated at $56,719,350, increasing to $61,324,263 (+ 8.1%), $59,121,545 (+ 4.2%) and $64,872,734 (+ 14.4%) in scenarios S2, S3 and S4, respectively. Compared with the status quo (S1), coverage rates were estimated to increase by 3.1% points with expanded delivery alone, and by 9.4 and 14.3% points, if the hexavalent vaccine is deployed (S2 and S4, respectively). In both scenarios with the hexavalent vaccine (S2 and S4), pertussis cases would also be 5.7% and 8.7% lower, and AR rates would decrease by 32%. The cost per protected child would be reduced when the hexavalent vaccine scheme. Incidence of ARs was an important driver of cost variability in the sensitivity analysis.ConclusionsImplementation of the hexavalent vaccine in Peru’s National Immunization Program has a positive public health cost consequence.

Immuno-persistence after the fourth and fifth doses of inactivated polio vaccines in school-aged children

ObjectivesThis study aimed to assess the long-term persistence of neutralizing antibodies (nAb) titres and seroprotection proportions after the fourth and fifth doses of inactivated polio vaccine (IPV). MethodsSerum samples from 299 children in Hong Kong were collected and used to estimate the persistence of nAb titres and seroprotection proportions by neutralisation test. ResultsThe mean nAb titres against poliovirus types 1, 2, and 3 (PV1, PV2, and PV3) 1 month after receiving the fourth dose of IPV at 19 months of age were 2068 (95% credible interval, 1517–2864); 4705 (3439–6436); and 2758 (1894–4086); respectively, but declined substantially in 4 years to 268 (222–325), 751 (630–900), and 411 (323–521), respectively. Administration of the fifth dose of IPV restored nAb titres among children aged 6 to 7 years, and the decline in nAb titres was slightly slower with the estimated mean titres of 355 (272–462), 538 (427–681), and 548 (378–786) against PV1, PV2, and PV3 at 4 years post the fifth dose. We estimated that the proportion of children who were seroprotected against PV1, PV2, and PV3 would drop below 90%: (i) 8.2, 10.8, and 8.7 years after the fourth dose; and (ii) 11.6, 11.2, and 11.0 years after the fifth dose. DiscussionThe results revealed the immuno-persistence after the fourth and fifth doses of IPV and highlighted the importance of completing immunization series to ensure high vaccination coverage, particularly among children in the developing countries affected by the COVID-19 pandemic.

Effect of a campaign with oral polio vaccine on general health: A cluster-randomised trial in rural Guinea-Bissau

To investigate in a cluster-randomised trial whether a campaign with oral polio vaccine (C-OPV) reduced mortality and morbidity. We randomised 222 village clusters under demographic surveillance to an intervention (health check and C-OPV) or control group (health check only). Children aged 0-8 months were eligible. In Cox proportional hazards models with age as the underlying timescale, we compared rates of non-accidental mortality/hospital admission (composite primary outcome) during 12 months of follow-up. Secondary analyses considered non-accidental admission and mortality as separate outcomes. Potential effect modifiers identified in prior studies including sex, season, and timing of the first routine OPV dose (OPV0, scheduled at birth) were assessed. Among 10,175 children (5,288 in 111 intervention clusters/4,887 in 111 control clusters), we observed 265 deaths/admissions during 7,616 person-years at risk (intervention: 129; control: 136). C-OPV did not reduce the composite endpoint, hazard ratio (HR): 0.87, 95%CI: 0.68-1.12 or its separate components. C-OPV reduced the risk in children receiving OPV0<15 days of birth (HR=0.66, 95%CI: 0.46-0.95), but not in other children (p for interaction: 0.03). Interactions for other potential effect modifiers were not statistically significant. C-OPV had no overall effect on mortality/admissions, but the effect differed by early priming with OPV0.

Protective role of antibodies in enteric virus infections: Lessons from primary and secondary immune deficiencies.

Enteric viruses are the main cause of acute gastroenteritis worldwide with a significant morbidity and mortality, especially among children and aged adults. Some enteric viruses also cause disseminated infections and severe neurological manifestations such as poliomyelitis. Protective immunity against these viruses is not well understood in humans, with most knowledge coming from animal models, although the development of poliovirus and rotavirus vaccines has extended our knowledge. In a classical view, innate immunity involves the recognition of foreign DNA or RNA by pathogen recognition receptors leading to the production of interferons and other inflammatory cytokines. Antigen uptake and presentation to T cells and B cells then activate adaptive immunity and, in the case of the mucosal immunity, induce the secretion of dimeric IgA, the more potent immunoglobulins in viral neutralization. The study of Inborn errors of immunity (IEIs) offers a natural opportunity to study nonredundant immunity toward pathogens. In the case of enteric viruses, patients with a defective production of antibodies are at risk of developing neurological complications. Moreover, a recent description of patients with low or absent antibody production with protracted enteric viral infections associated with hepatitis reinforces the prominent role of B cells and immunoglobulins in the control of enteric virus.