Decline in Vaccination Coverage against Poliomyelitis in the municipalities of Vale do Paraíba (SP) under a spatial approach.

OBJECTIVE: To analyze vaccination coverage (VC) for polio in the municipalities of Vale do Paraíba in the State of São Paulo. METHODS: This is an ecological and exploratory study of VC in 35 municipalities using a spatial approach; VC data were obtained from the IT Department of the Unified Health System (DATASUS), for the years 2015 and 2019, and categorized into Low (VC<95%) and ideal (≥95%). Information was obtained on gross domestic product (GDP), professional rates and number of basic health units (UBS) and maternal data such as age, marital status (MS) and education. Univariate and bivariate Moran indices were estimated for the years 2015 and 2019, and thematic maps were created for CV values. RESULTS: The average VC values were 107.7%±27.2 in 2015, and 94.2%±27.8 in 2019 (p<0.05). In 2015 vs. 2019, there were 10 vs. 25 municipalities in the Low category. In 2015, the variables VC, number of UBS, age, education, and MS were spatially correlated, but in 2019 only maternal age and education were spatially correlated. The bivariate Moran was significant and negative for VC in 2019 with maternal education. There was an increase in municipalities with worsening VC values. CONCLUSIONS: The spatial approach identified a decrease in polio vaccination coverage in the studied region.

15th Meeting of the Regional Certification Commission for the Polio Endgame in the Region of the Americas. Meeting Report. Atlanta, 25-27 October 2022

The 15th Meeting of the Regional Certification Commission for the Eradication of Poliomyelitis in the Region of the Americas (RCC) was held in Atlanta, Georgia, United States of America from 25-27 October 2022. All members of the RCC discussed and approved the validation results and the final report of the meeting. The objectives of the meeting were: meet with the National Poliovirus Containment Coordinators (NPCCs) of the countries that had not received validation of the survey/inventory process of facilities with poliovirus material; review the updated containment reports that were submitted by the countries; meet with representatives of the United States’ domestic polio program and the National Certification Committee (NCC) to discuss the current cVDPV2 outbreak situation in New York, United States of America; review annual reports from countries that did not submit the 2021 Annual Report on time for review during the 14th Meeting; and update the annual report format and review the validation questions. The Regional Certification Commission greatly appreciates the hard work of the NCCs and countries in preparing their reports to be reviewed by the Regional Certification Commission. The Regional Certification Commission would like to thank the Task Force for Global Health, which serves as the United States’ NCC Secretariat, for its kind support in preparing for and convening the meeting and for lending its facilities to the Regional Certification Commission for this meeting. The Regional Certification Commission also recognizes and values the work of PAHO in its ongoing support to the RCC.

Evolution of global polio eradication strategies: targets, vaccines, and supplemental immunization activities (SIAs).

BACKGROUND: Despite multiple revisions of targets and timelines in polio eradication plans since 1988, including changes in supplemental immunization activities (SIAs) that increase immunity above routine immunization (RI) coverage, poliovirus transmission continues as of 2024. METHODS: We reviewed polio eradication plans and Global Polio Eradication Initiative (GPEI) annual reports and budgets to characterize key phases of polio eradication, the evolution of poliovirus vaccines, and the role of SIAs. We used polio epidemiology to provide context for successes and failures and updated prior modeling to show the contribution of SIAs in achieving and maintaining low polio incidence compared to expected incidence for the counterfactual of RI only. RESULTS: We identified multiple phases of polio eradication that included shifts in targets and timelines and the introduction of different poliovirus vaccines, which influenced polio epidemiology. Notable shifts occurred in GPEI investments in SIAs since 2001, particularly since 2016. Modeling results suggest that SIAs play(ed) a key role in increasing (and maintaining) high population immunity to levels required to eradicate poliovirus transmission globally. CONCLUSIONS: Shifts in polio eradication strategy and poliovirus vaccine usage in SIAs provide important context for understanding polio epidemiology, delayed achievement of polio eradication milestones, and complexity of the polio endgame.

Progress Toward Poliomyelitis Eradication - Worldwide, January 2022-December 2023.

In 1988, poliomyelitis (polio) was targeted for eradication. Global efforts have led to the eradication of two of the three wild poliovirus (WPV) serotypes (types 2 and 3), with only WPV type 1 (WPV1) remaining endemic, and only in Afghanistan and Pakistan. This report describes global polio immunization, surveillance activities, and poliovirus epidemiology during January 2022-December 2023, using data current as of April 10, 2024. In 2023, Afghanistan and Pakistan identified 12 total WPV1 polio cases, compared with 22 in 2022. WPV1 transmission was detected through systematic testing for poliovirus in sewage samples (environmental surveillance) in 13 provinces in Afghanistan and Pakistan, compared with seven provinces in 2022. The number of polio cases caused by circulating vaccine-derived polioviruses (cVDPVs; circulating vaccine virus strains that have reverted to neurovirulence) decreased from 881 in 2022 to 524 in 2023; cVDPV outbreaks (defined as either a cVDPV case with evidence of circulation or at least two positive environmental surveillance isolates) occurred in 32 countries in 2023, including eight that did not experience a cVDPV outbreak in 2022. Despite reductions in paralytic polio cases from 2022, cVDPV cases and WPV1 cases (in countries with endemic transmission) were more geographically widespread in 2023. Renewed efforts to vaccinate persistently missed children in countries and territories where WPV1 transmission is endemic, strengthen routine immunization programs in countries at high risk for poliovirus transmission, and provide more effective cVDPV outbreak responses are necessary to further progress toward global polio eradication.

Erradicación de la poliomielitis en España: ¿qué ha pasado en la última década? / Eradication of poliomyelitis in Spain: What has happened in the last decade?

Al cumplirse sesenta años desde el inicio de la campaña de vacunación frente a la poliomielitis en España, se destaca el importante hito en el control de la enfermedad que ha supuesto el cambio desde una incidencia de más de 2.000 casos anuales en la década de los 60 a una ausencia mantenida de poliovirus (PV) salvaje desde 1988. A pesar del impacto negativo observado en las coberturas de vacunación de poliomielitis al inicio de la pandemia de COVID-19, estas se fueron recuperando, alcanzando un 98,2% en la primovacunación en 2022. En la última década, se han identificado dos elementos esenciales para mantener el objetivo de eliminación de la poliomielitis y que, además, refuerzan la importancia de mantener altas coberturas de vacunación: los sistemas de vigilancia epidemiológica robustos y la respuesta rápida a las alertas para proteger a la población vulnerable y evitar la circulación del virus. Es crucial interrumpir la transmisión a nivel internacional para lograr la erradicación, manteniendo una vigilancia continua de alta calidad y una coordinación efectiva entre los diferentes niveles frente a cualquier detección de PV, ya sea salvaje o derivado de la vacuna.(AU)

On the 60th anniversary of the initiation of the polio vaccination campaign in Spain, the significant milestone in achieving disease control is highlighted. There has been a shift from an incidence of over 2,000 yearly cases in the 1960s to a sustained absence of wild poliovirus (WPV) since 1988. Despite the observed negative impact on polio vaccination coverage at the onset of the COVID-19 pan-demic, these rates gradually recovered, reaching 98.2% in primary vaccination in 2022. Over the past decade, two essential elements have been identified to maintain the goal of polio elimination and that reinforces the importance of sustaining high vaccination co-verage: robust epidemiological surveillance systems and a swift response to alerts to protect the vulnerable population and prevent virus reintroduction. In order to achieve eradication, it is crucial to interrupt international transmission and maintain continuous high-quality surveillance and effective coordination across different levels in response to any detection of PV, wild or vaccine derived.This article aimed to provide a comprehensive view of the polio eradication situation in Spain, focusing on the key events that occu-rred in the last decade and the present and future challenges.(AU)

Establishment of the Daucus carota SMC-1 Cell Suspension Line for Poliovirus Vaccine Development.

The development of virus-free, oral vaccines against poliovirus capable of inducing mucosal protective immunity is needed to safely combat this pathogen. In the present study, a carrot cell line expressing the poliovirus VP2 antigen was established at the level of callus and cell suspensions, exploring the effects of culture media (MS and B5), supplementation with urea, phytoregulators (2,4-D : KIN), and light conditions (continuous light, photoperiod, and total darkness). The best callus growth was obtained on B5 medium supplemented with 2 mg/L of 2,4-D + 2 mg/L kinetin and 0.0136 g/L of urea and in continuous light conditions. Suspension cultures of the SMC-1 line in 250 mL Erlenmeyer flasks had a maximum growth of 16.07 ± 0.03 g/L DW on day 12 with a growth rate of µ=0.3/d and a doubling time of 2.3 days. In a 2 L airlift bioreactor, the biomass yield achieved was 25.6 ± 0.05 g/L DW at day 10 with a growth rate of µ= 0.58/d and doubling time of 1.38 d. Cell growth was 1.5 times higher in bioreactors than in shake flasks, highlighting that both systems resulted in the accumulation of VP2 throughout the time in culture. The maximum VP2 yield in flasks was 387.8 µg/g DW at day 21, while in the reactor it was 550.2 µg/g DW at day 18. In conclusion, bioreactor-based production of the VP2 protein by the SMC-1 suspension cell line offers a higher productivity when compared to flask cultures, offering a key perspective to produce low-cost vaccines against poliomyelitis.

16th meeting of the Regional Certification Commission for the Polio Endgame in the Region of the Americas: Meeting report. 24- 27 July 2023, Panama City, Panama

The 16th Meeting of the Regional Certification Commission (RCC) for Polio Eradication in the Region of the Americas was held in Panama City, Panama, from July 24 to 27 2023. During the meeting, the RCC discussed and validated the annual reports of 22 countries and the report of the Caribbean subregion, which includes information from 13 countries and 9 territories. The reports were presented with information on the performance of the polio vaccination program and the eradication status in 2022. All RCC members discussed and approved the general recommendations, country validation results, and the report. end of the meeting.

16ª Reunión de la Comisión Regional de Certificación de la Erradicación de la Polio en la Región de las Américas

La 16ª Reunión de la Comisión Regional de Certificación de la Erradicación de la Poliomielitis en la Región de las Américas (RCC) se celebró en Ciudad de Panamá, Panamá, del 24 al 27 de julio de 2023. La RCC recibió los informes de los 22 países y el informe de la subregión del Caribe, tal como estaba previsto. El informe anual incluye información sobre el desempeño del programa contra la poliomielitis y el estado de la erradicación de la poliomielitis en el 2022 de cada país de las Américas. La RCC revisó y validó los informes en torno a 7 preguntas sobre la cobertura de vacunación contra la poliomielitis, la vigilancia de la poliomielitis, la contención de poliovirus, la evaluación y mitigación de riesgos, la preparación para eventos y brotes de poliomielitis, el riesgo de circulación de poliovirus no detectados y la evaluación de que el país esté libre de poliomielitis. La RCC evaluó el riesgo de que los países tuvieran circulación de poliovirus en caso de importación o aparición de poliovirus, y los países se clasificaron como de riesgo muy alto, alto, medio o bajo. Aunque el número de países clasificados como de riesgo alto y muy alto de poliomielitis ha disminuido con respecto al año anterior, los países deben seguir aplicando medidas de mitigación del riesgo. La RCC concluyó que, dada la identificación del VDPV en tres países de la Región (Canadá, Perú y los Estados Unidos de América) durante el 2022, este fue un año especialmente difícil. El presente informe incluye un resumen de la reunión, los resultados de la validación de los informes anuales presentados por los países, la evaluación regional del riesgo de brotes de poliomielitis para el 2023 y las recomendaciones generales formuladas por la RCC para los países de las Américas.

Polio outbreak response, Yemen.

Problem: A decrease in vaccine coverage in conflict-affected areas has placed Yemen at higher risk of polio outbreaks caused by vaccine-derived poliovirus strains. Approach: In response to polio outbreaks, the Yemeni health ministry and partners initiated multiple vaccination campaigns to deliver vaccines to children. We also implemented several measures to enhance communication, education, health promotion and hygiene, especially in camps for internally displaced people. Local setting: In 2009, Yemen achieved polio-free status and maintained it until 2019. However, the ongoing political conflict since 2015, coupled with challenges in delivering the polio vaccine to conflict-affected areas, resulted in two polio outbreaks: 35 cases caused by vaccine-derived poliovirus strain 1 between 2019 and 2021, and 230 cases due to vaccine-derived poliovirus strain 2 between November 2021 and December 2022. Relevant changes: In response to the first outbreak, by the end of 2020, we vaccinated 7.2 million children through nationwide vaccination campaigns, except in Sa'ada governorate due to a ban by the authorities. By the end of 2021, 3 800 313 children younger than 5 years had received polio vaccines. For the second outbreak, by the end of 2022, 4 463 389 vaccines had been given to children younger than 10 years, and 1 217 423 to those younger than 5 years. Lessons learnt: Vaccination campaigns in conflict-affected areas with low vaccine coverage remain crucial in eradicating polio. Efforts are needed to reach vulnerable groups such as displaced populations. Advocacy, communication and social mobilization actions help ensure broader public inclusion and participation in vaccination efforts to prevent polio outbreaks.

Oral polio vaccine stockpile modeling: insights from recent experience.

BACKGROUND: Achieving polio eradication requires ensuring the delivery of sufficient supplies of the right vaccines to the right places at the right times. Despite large global markets, decades of use, and large quantity purchases of polio vaccines by national immunization programs and the Global Polio Eradication Initiative (GPEI), forecasting demand for the oral poliovirus vaccine (OPV) stockpile remains challenging. RESEARCH DESIGN AND METHODS: We review OPV stockpile experience compared to pre-2016 expectations, actual demand, and changes in GPEI policies related to the procurement and use of type 2 OPV vaccines. We use available population and immunization schedule data to explore polio vaccine market segmentation, and its role in polio vaccine demand forecasting. RESULTS: We find that substantial challenges remain in forecasting polio vaccine needs, mainly due to (1) deviations in implementation of plans that formed the basis for earlier forecasts, (2) lack of alignment of tactics/objectives among GPEI partners and other key stakeholders, (3) financing, and (4) uncertainty about development and licensure timelines for new polio vaccines and their field performance characteristics. CONCLUSIONS: Mismatches between supply and demand over time have led to negative consequences associated with both oversupply and undersupply, as well as excess costs and potentially preventable cases.

The role of a genetically stable, novel oral type 2 poliovirus vaccine in the poliomyelitis endgame

[ABSTRACT]. Poliovirus infection causes paralysis in up to 1 in 200 infected persons. The use of safe and effective inactivated poliovirus vaccines and live attenuated oral poliovirus vaccines (OPVs) means that only two pockets of wild- type poliovirus type 1 remain, in Afghanistan and Pakistan. However, OPVs can revert to virulence, causing outbreaks of circulating vaccine-derived poliovirus (cVDPV). During 2020–2022, cVDPV type 2 (cVDPV2) was responsible for 97–99% of poliomyelitis cases, mainly in Africa. Between January and August 2022, cVDPV2 was detected in sewage samples in Israel, the United Kingdom and the United States of America, where a case of acute flaccid paralysis caused by cVDPV2 also occurred. The Pan American Health Organization has warned that Brazil, the Dominican Republic, Haiti and Peru are at very high risk for the reintroduction of polio- virus and an additional eight countries in Latin America are at high risk, following dropping vaccination rates (average 80% coverage in 2022). Sabin type 2 monovalent OPV has been used to control VDPV2 outbreaks, but its use could also lead to outbreaks. To address this issue, a more genetically stable, novel OPV2 (nOPV2) was developed against cVDPV2 and in 2020 was granted World Health Organization Emergency Use Listing. Rolling out a novel vaccine under the Emergency Use Listing in mass settings to contain outbreaks requires unique local regulatory and operational preparedness.

[RESUMEN]. La infección por poliovirus ocasiona parálisis en hasta 1 de cada 200 personas infectadas. La utilización de vacunas con poliovirus inactivados y de vacunas antipoliomielíticas orales con poliovirus vivos atenuados (OPV) seguras y eficaces ha logrado que solo queden dos focos de poliovirus salvaje de tipo 1, en Afganistán y Pakistán. Sin embargo, las vacunas con OPV pueden revertir a la virulencia y producir brotes de poliovi- rus circulantes de origen vacunal (cVDPV). Durante el período 2020-2022, el cVDPV de tipo 2 (cVDPV2) fue la causa del 97-99% de los casos de poliomielitis, sobre todo en África. Entre enero y agosto del 2022, se encontró el cVDPV2 en muestras de aguas residuales en Estados Unidos de América, donde se produjo un caso de parálisis flácida aguda por el cVDPV2, Israel y Reino Unido y. La Organización Panamericana de la Salud ha advertido que, tras la caída de las tasas de vacunación (con una cobertura promedio del 80% en el 2022), Brasil, Haití, Perú y República Dominicana corren un riesgo muy alto de reintroducción del poliovirus, en tanto que otros ocho países de América Latina se encuentran en una situación de alto riesgo. La OPV mon- ovalente de tipo 2 de Sabin se ha utilizado para controlar los brotes de VDPV2, pero su empleo también podría ocasionar brotes. Para hacer frente a este problema, se creó una nueva OPV2 (nOPV2) contra el cVDPV2, genéticamente más estable, que en el 2020 se incluyó en la lista de uso en emergencias de la Organización Mundial de la Salud. El despliegue a gran escala de una nueva vacuna incluida en la lista de uso en emergen- cias con el fin de contener los brotes exige una extraordinaria preparación regulatoria y operativa local.

[RESUMO]. A infecção pelo poliovírus causa paralisia em 1 de cada 200 pessoas infectadas. O uso de vacinas seguras e eficazes, tanto vacinas inativadas contra o poliovírus quanto vacinas orais contendo poliovírus atenuado (VOP), significa que restam apenas dois bolsões de poliovírus selvagem tipo 1, um no Afeganistão e outro no Paquistão. No entanto, a VOP pode reverter à virulência, causando surtos de poliovírus circulante derivado de vacina (cPVDV). No período 2020-2022, o cPVDV tipo 2 (cPVDV2) foi responsável por 97% a 99% dos casos de poliomielite, principalmente na África. Entre janeiro e agosto de 2022, o cPVDV2 foi detectado em amostras de esgoto em Israel, no Reino Unido e nos Estados Unidos da América, onde também houve um caso de paralisia flácida aguda causada pelo cPVDV2. A Organização Pan-Americana da Saúde alertou que, devido à queda nas taxas de vacinação (cobertura média de 80% em 2022), o Brasil, o Haiti, o Peru e a República Dominicana correm um risco muito alto de reintrodução do poliovírus e outros oito países da América Latina correm um risco alto. A VOP monovalente Sabin tipo 2 tem sido usada para controlar surtos de PVDV2, mas seu uso também pode levar a surtos. Para resolver esse problema, foi desenvolvida uma nova VOP2 (nVOP2), mais estável geneticamente, para combater o cPVDV2. Em 2020, a nVOP2 entrou na Lista de Uso Emergencial da Organização Mundial da Saúde. A distribuição de uma nova vacina incluída na Lista de Uso Emergencial em contextos de massa para conter surtos requer medidas originais de preparação operacional e regulatória em âmbito local.

Prevalence of poliovirus neutralizing antibodies in Italian population: A systematic review and meta-analysis.

INTRODUCTION: The introduction of anti-poliomyelitis vaccines has driven progress toward the global eradication of wild polioviruses, a millennium goal of the World Health Organization. With the vaccination campaigns carried out since 1964, in 2002 Italy was certified polio-free, considering that no cases had been recorded since 1983. Nevertheless, it is crucial to guarantee high level of immunization coverage also in low-endemicity countries, considering that sporadic polio cases can be recorded. To evaluate the presence of susceptible subjects in the population, seroepidemiological studies are key actions. METHODS: We conducted a systematic review of the relevant literature to evaluate the prevalence of anti-PV neutralizing antibodies in Italian population. Seven studies, selected among scientific articles available in MEDLINE/PubMed, ISI Web of Knowledge and Scopus and published from January 1, 2012, to November 15, 2022, were included. RESULTS: The pooled prevalence of subjects without PV1 neutralizing antibodies was 6.4% (95%CI = 0.5-16.9), for PV2 it was 5.3% (95%CI = 0.4-14.2), and for PV3 it was 13.0% (95%CI = 4.0-25.7; I2 = 98.5%). Levels of neutralizing antibodies appears to decrease with increasing age; this decline is a proxy for the real risk factor, which is the time since the last vaccine dose. CONCLUSIONS: Public health institutions must be aware of the risk of reintroduction of wild PV in polio-free countries and therefore they must keep high level of immunization in population and reinforce the active surveillance systems.

PAHO Strategic Response Plan and Appeal: Polio

This publication contains information on the response plan and financial appeal to respond to the emergency declared in relations to Polio.

Polio eradication: Addressing the hurdles on the last mile.

1988, the World Health Assembly committed to eradicate poliomyelitis, a viral disease that can cause permanent paralysis. Today, only type 1 of the three wild poliovirus types remains circulating in limited geographic areas following widespread use of different poliovirus vaccines. While we are close to zero new cases of wild polio, it is a fragile situation, and there are many remaining and new hurdles to overcome. Here, experts discuss how to address them.