Wild poliovirus makes comeback in Afghanistan and Pakistan.

2024 target of ending all transmission will likely be missed.

Intestinal mucosal immunity is unimportant for polio eradication: the failure of oral polio vaccination.

AIMS: To explore if intestinal immunity induced by infection with live viruses in the oral poliovirus vaccine (OPV) is essential, necessary or even helpful in interrupting transmission of wild poliovirus (WPV) for global polio eradication. METHODS: We reviewed the biology of virus-host interactions in WPV infection and its alterations by OPV-induced immunity for direct evidence of the usefulness of intestinal immunity. We also explored indirect evidence by way of the effect of the inactivated poliovirus vaccine (IPV) on the biology and on transmission dynamics of WPV. RESULTS: Immunity, systemic and intestinal, induced by infection with WPV or vaccine viruses, does not prevent re-infection with WPV or vaccine viruses respectively, when exposed. Such re-infected hosts shed virus in the throat and in faeces and are sources of further transmission. Immunity protects against polio paralysis-hence reinfection always remain asymptommatic and silent. CONCLUSION: Vaccine virus-induced intestinal immunity is not necessary for polio eradication. The continued and intensive vaccination efforts using OPV under the assumption of its superiority over IPV have resulted in the well-known undesirable effects, namely vaccine associated paralytic polio and the emergence of de-attenuated circulating vaccine-derived polioviruses, in addition to the delay in completing global WPV eradication.

Development of a Consolidated Health Facility Masterlist Using Data From Polio Electronic Surveillance in the World Health Organization African Region.

Geospatial data reporting from surveillance and immunization efforts is a key aspect of the World Health Organization (WHO) Global Polio Eradication Initiative in Africa. These activities are coordinated through the WHO Regional Office for Africa Geographic Information Systems Centre. To ensure the accuracy of field-collected data, the WHO Regional Office for Africa Geographic Information Systems Centre has developed mobile phone apps such as electronic surveillance (eSURV) and integrated supportive supervision (ISS) geospatial data collection programs. While eSURV and ISS have played a vital role in efforts to eradicate polio and control other communicable diseases in Africa, disease surveillance efforts have been hampered by incomplete and inaccurate listings of health care sites throughout the continent. To address this shortcoming, data compiled from eSURV and ISS are being used to develop, update, and validate a Health Facility master list for the WHO African region that contains comprehensive listings of the names, locations, and types of health facilities in each member state. The WHO and Ministry of Health field officers are responsible for documenting and transmitting the relevant geospatial location information regarding health facilities and traditional medicine sites using the eSURV and ISS form; this information is then used to update the Health Facility master list and is also made available to national ministries of health to update their respective health facility lists. This consolidation of health facility information into a single registry is expected to improve disease surveillance and facilitate epidemiologic research for the Global Polio Eradication Initiative, as well as aid public health efforts directed at other diseases across the African continent. This review examines active surveillance using eSURV at the district, country, and regional levels, highlighting its role in supporting polio surveillance and immunization efforts, as well as its potential to serve as a fundamental basis for broader public health initiatives and research throughout Africa.

The evolution, facilitators, barriers, and additional activities of acute flaccid paralysis surveillance platform in polio eradication programme Bangladesh: a mixed-method study.

BACKGROUND: The Global Polio Eradication Initiative (GPEI) helped develop the standard acute flaccid paralysis surveillance (AFP) system worldwide, including, knowledge, expertise, technical assistance, and trained personnel. AFP surveillance can complement any disease surveillance system. OBJECTIVE: This study outlines AFP surveillance evolution in Bangladesh, its success and challenging factors, and its potential to facilitate other health goals. METHODS: This mixed-method study includes a grey literature review, survey, and key informant interviews (KIIs). We collected grey literature from online websites and paper documentation from GPEI stakeholders. Online and in-person surveys were conducted in six divisions of Bangladesh, including Dhaka, Rajshahi, Rangpur, Chittagong, Sylhet, and Khulna, to map tacit knowledge ideas, approaches, and experiences. We also conducted KIIs, and Data were then combined on focused emerging themes, including the history, challenges, and successes of AFP surveillance programme. RESULTS: According to the grey literature review, survey, and KII, AFP surveillance successfully contributed to decreasing polio in Bangladesh. The major facilitating factors were multi-sectoral collaboration, Surveillance Immunization Medical Officer (SIMO) network activities, social environment, community-based surveillance, and promising political commitment. On the other hand, high population growth, hard-to-reach areas, people residing in risky zones, and polio transition planning were significant challenges. Bangladesh is also utilizing these polio surveillance assets for other vaccine-preventable diseases. CONCLUSION: As the world is so close to eradicating polio, the knowledge, and other assets of the AFP surveillance, could be used for other health programmes. In addition, its strengths can be leveraged for combating new and emerging diseases.

Main findings: The research found that Bangladesh has achieved a world-standard surveillance system, with facilitating factors including multi-sectoral collaboration, GPEI partners, and political and community support. However, high population growth, hard-to-reach areas and people, and polio transition planning were found to be challenges.Added knowledge: In addition, Bangladesh is now utilizing these polio surveillance assets to monitor other vaccine-preventable diseases.Global health impact for policy and action: Since polio is still a threat to some LMICs, the knowledge gained from AFP surveillance of Bangladesh could assist those countries in eradicating the cases of polio from the earth and serve VPDs and other health programmes as well.

Persistent Transmission of Circulating Vaccine-Derived Poliovirus - Somalia, January 2017-March 2024.

Since the launch of the Global Polio Eradication Initiative in 1988, substantial progress has been made in the interruption of wild poliovirus (WPV) transmission worldwide: global eradication of WPV types 2 and 3 were certified in 2015 and 2019, respectively, and endemic transmission of WPV type 1 continues only in Afghanistan and Pakistan. After the synchronized global withdrawal of all serotype 2 oral poliovirus vaccines (OPVs) in 2016, widespread outbreaks of circulating vaccine-derived poliovirus type 2 (cVDPV2) have occurred, which are linked to areas with low population immunity to poliovirus. Officials in Somalia have detected ongoing cVDPV2 transmission since 2017. Polio vaccination coverage and surveillance data for Somalia were reviewed to assess this persistent transmission. During January 2017-March 2024, officials in Somalia detected 39 cVDPV2 cases in 14 of 20 regions, and transmission has spread to neighboring Ethiopia and Kenya. Since January 2021, 28 supplementary immunization activities (SIAs) targeting cVDPV2 were conducted in Somalia. Some parts of the country are security-compromised and inaccessible for vaccination campaigns. Among 1,921 children with nonpolio acute flaccid paralysis, 231 (12%) had not received OPV doses through routine immunization or SIAs, 95% of whom were from the South-Central region, and 60% of whom lived in inaccessible districts. Enhancing humanitarian negotiation measures in Somalia to enable vaccination of children in security-compromised areas and strengthening campaign quality in accessible areas will help interrupt cVDPV2 transmission.

Application of MPBT Assay for Multiplex Determination of Infectious Titers and for Selection of the Optimal Formulation for the Trivalent Novel Oral Poliovirus Vaccine.

Recently, a multiplex PCR-based titration (MPBT) assay was developed for simultaneous determination of infectious titers of all three Sabin strains of the oral poliovirus vaccine (OPV) to replace the conventional CCID50 assay, which is both time-consuming and laborious. The MPBT assay was shown to be reproducible, robust and sensitive. The conventional and MPBT assays showed similar results and sensitivity. The MPBT assay can be completed in two to three days, instead of ten days for the conventional assay. To prevent attenuated vaccine strains of poliovirus from reversion to virulence, a novel, genetically stable OPV (nOPV) was developed by modifying the genomes of conventional Sabin strains used in OPV. In this work, we evaluated the MPBT assay as a rapid screening tool to support trivalent nOPV (tnOPV) formulation development by simultaneous titration of the three nOPV strains to confirm stability as needed, for the selection of the lead tnOPV formulation candidate. We first assessed the ability of the MPBT assay to discriminate a 0.5 log10 titer difference by titrating the two tnOPV samples (undiluted and threefold-diluted) on the same plate. Once the assay was shown to be discriminating, we then tested different formulations of tnOPV drug products (DPs) that were subjected to different exposure times at 37 °C (untreated group and treated groups: 2 and 7 days at 37 °C), and to three freeze and thaw (FT) cycles. Final confirmation of the down selected formulation candidates was achieved by performing the conventional CCID50 assay, comparing the stability of untreated and treated groups and FT stability testing on the top three candidates. The results showed that the MPBT assay generates similar titers as the conventional assay. By testing two trivalent samples in the same plate, the assay can differentiate a 0.5 log10 difference between the titers of the tested nOPV samples. Also, the assay was able to detect the gradual degradation of nOPV viruses with different formulation compositions and under different time/temperature conditions and freeze/thaw cycles. We found that there were three tnOPV formulations which met the stability criteria of less than 0.5 log10 loss after 2 days' exposure to 37 ℃ and after three FT cycles, maintaining the potency of all three serotypes in these formulations. The ability of the MPBT assay to titrate two tnOPV lots (six viruses) in the same plate makes it cheaper and gives it a higher throughput for rapid screening. The assay detected the gradual degradation of the tnOPV and was successful in the selection of optimal formulations for the tnOPV. The results demonstrated that the MPBT method can be used as a stability indicating assay to assess the thermal stability of the nOPV. It can be used for rapid virus titer determination during the vaccine manufacturing process, and in clinical trials. The MPBT assay can be automated and applied for other viruses, including those with no cytopathic effect.

Vaccine-associated paralytic poliomyelitis in oral polio vaccine recipients: disproportionality analysis using VAERS and systematic review.

BACKGROUND: Vaccine-associated paralytic poliomyelitis (VAPP) is a rare adverse event of oral poliovirus vaccines (OPV), particularly affecting immunodeficient individuals. RESEARCH DESIGN AND METHODS: This study aimed to (1) Assess the association between OPV and VAPP using Vaccine Adverse Event Reporting System (VAERS) database (2) Outline patient characteristics and risk factors associated with the occurrence of VAPP in OPV recipients through a systematic review of case reports and case series. A disproportionality analysis was conducted using the data from VAERS, encompassing adverse events reported from 1990 till February 2023. Additionally, we conducted a systematic review of case reports and case series using PubMed, Scopus, and Embase databases. RESULTS: The VAERS data revealed 130 VAPP reports among 1,739,903 OPV linked adverse events, with year 2010 reporting the strongest association. The systematic review of 37 studies highlighted VAPP occurrence within 2 months to 4 years post-vaccination, typically with acute flaccid paralysis. Immunodeficiency and perianal abscess emerged as major risk factors. Out of the 37 included studies, 27 showed consistent causal association of VAPP with OPV using WHO-AEFI causality assessment tool. CONCLUSION: The study emphasized the seriousness of VAPP and highlights its association with OPV, identifying immunodeficiency as a prominent contributor to VAPP manifestation.

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.

The history of polio vaccination with "Sabin's OPV" 60 years after its introduction in Italy: an unforgivable "delay".

In the spring of 1964, polio vaccination with the oral vaccine developed by Albert Sabin began in Italy. Polio was feared in the world and in Italy. Thus, between 1957 and the beginning of 1958, Italian children began receiving the "Salk vaccine", though the results were not particularly convincing. In July 1960, the international scientific community was able to verify the data from the mass testing of the Sabin vaccine. It became clear that the OPV, could prevent the virus from multiplying, thereby providing greater protection and determining the eradication of the disease. In 1960 over 70 million people in the USSR alone had already received the oral vaccine and mass vaccination in the USA would start in March 1961. However, in Italy there was no similar initiative; only later the new vaccine was accepted but was not made compulsory at the beginning. As a result of the commission's report, registration of the "Polioral" vaccine, was authorized in September 1962 but the sale of the vaccine was not authorized until November 1963. At the beginning of 1964, the production of "Polioral" started and the product was marketed and on the 1 st of March 1964, anti-polio vaccination with the "Sabin anti-polio vaccine" also began in Italy. This manuscript focuses on a crucial issue about a historical delay for public health and it points out as the preparation and diffusion of the Sabin polio vaccine demonstrates that decisions regarding health treatments, and specifically vaccination campaigns, must be based exclusively on the results of clinical studies and on independent evaluation by the scientific community. This process ensures trust in vaccines, adequate protection of public health andcitizens' well-being.

Immunogenicity evaluation of primary polio vaccination schedule with inactivated poliovirus vaccines and bivalent oral poliovirus vaccine.

BACKGROUND: To assess the immunogenicity of the current primary polio vaccination schedule in China and compare it with alternative schedules using Sabin or Salk-strain IPV (sIPV, wIPV). METHODS: A cross-sectional investigation was conducted at four sites in Chongqing, China, healthy infants aged 60-89 days were conveniently recruited and divided into four groups according to their received primary polio vaccination schedules (2sIPV + bOPV, 2wIPV + bOPV, 3sIPV, and 3wIPV). The sero-protection and neutralizing antibody titers against poliovirus serotypes (type 1, 2, and 3) were compared after the last dose. RESULTS: There were 408 infants completed the protocol. The observed seropositivity was more than 96% against poliovirus types 1, 2, and 3 in all groups. IPV-only groups induced higher antibody titers(GMT) against poliovirus type 2 (Median:192, QR: 96-384, P<0.05) than the "2IPV + bOPV" group. While the "2IPV + bOPV" group induced significantly higher antibody titers against poliovirus type 1 (Median:2048, QR: 768-2048, P<0.05)and type 3 (Median:2048, QR: 512-2048, P<0.05) than the IPV-only group. CONCLUSIONS: Our findings have proved that the two doses of IPV with one dose of bOPV is currently the best polio routine immunization schedule in China.

Report offers harsh verdict on global polio vaccine switch.

Draft evaluation calls 2016 decision to change oral vaccines a "failure".

From legacy to integration in the Global Polio Eradication Initiative: looking back to look forward.

INTRODUCTION: The Global Polio Eradication Initiative (GPEI) is a global single-disease programme with an extensive infrastructure in some of the world's most underserved areas. It provides a key example of the opportunities and challenges of transition efforts-the process of shifting from donor-funded, single-disease programmes to programmes with more integrated and sustainable programmatic and funding streams. Our goal is to closely analyse the social and political dynamics of the polio transition in the 2010s to provide insights into today, as well as lessons for other programmes. METHODS: We conducted semistructured interviews with GPEI officials involved in transition planning across GPEI partner agencies (n=11). We also drew on document review and interviews with national and subnational actors in Nigeria, India, Ethiopia and the Democratic Republic of the Congo. We inductively analysed this material to capture emergent themes in the evolution of transition activities in the GPEI. RESULTS: Since the mid-2010s, GPEI actors expressed concern that polio's assets should not be lost when polio was eradicated. Planning for polio's legacy, however, proved complicated. The GPEI's commitment to and focus on eradication had taken precedence over strong collaborations outside the polio programme, making building alliances for transition challenging. There were also complex questions around who should be responsible for the transition process, and which agencies would ultimately pay for and deliver polio-funded functions. Current efforts to achieve 'integration' both have great promise and must grapple with these same issues. DISCUSSION: Within the GPEI, relinquishing control to other programmes and planning for significant, long-term funding for transition will be central to achieving successful integration and eventual transition. Beyond polio, other vertical programmes can benefit from going beyond transition 'planning' to integrate transition into the initial design of vertical programmes.

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.

Coverage, spatial distribution and determinants of childhood inactivated poliovirus vaccine immunization in Ethiopia.

INTRODUCTION: Polio eradication is a current and common strategy throughout the globe. The study of the newly introduced inactivated poliovirus vaccine provides a grasp on the current status of immunization and identifies any disparities in the implementation of the vaccine throughout Ethiopia. Thus, this study aimed to demonstrate the spatial distribution, coverage, and determinants of inactivated poliovirus vaccine immunization in Ethiopia. METHOD: Spatial distribution and determinants of inactivated poliovirus vaccine immunization in Ethiopia were conducted using Ethiopian mini-demographic and health survey 2019 data. A total of 2,056 weighted children aged 12 to 35 months were included in the analysis. The association between the outcome and explanatory variables was determined by commuting the adjusted odds ratio at a 95% confidence interval. The p-value of less than 0.05 was used to declare factors as significantly associated with the inactivated poliovirus vaccine immunization. RESULT: The weighted national coverage of inactivated poliovirus vaccine immunization in Ethiopia was 51.58% at a 95% confidence interval (49.42, 53.74). While the rates of inactivated poliovirus vaccine immunization were observed to be greater in Addis Ababa, Tigiray, Amahara, and Benishangul Gumuz provinces and lower in the Somali, Afar, and SNNPR provinces of Ethiopia, Antenatal care follow-up, place of delivery, place of residence, and region were significantly associated with inactivated poliovirus immunization in Ethiopia. CONCLUSION: The distribution of inactivated poliovirus immunization was spatially variable across Ethiopia. Only about half of the children aged twelve to thirty-five months received the inactivated poliovirus vaccine in the country. The factors, both at the individual and community level, were significantly associated with inactivated poliovirus immunization. Therefore, policies and strategies could benefit from considering antenatal care follow-up, place of delivery, place of residence, and region while implementing inactivated poliovirus vaccine immunization.

Impact of COVID -19 on expanded programme on Immunisation in District Dir lower Khyber Pakhtunkhwa.

Objectives: To study the impact of coronavirus disease-2019 on Expanded Programme on Immunisation in a rural setting. METHODS: The descriptive, cross-sectional study was conducted in five union councils of District Dir Lower, in the Khyber Pakhtunkhwa province of Pakistan. Data was collected from March to August 2020, which was a period of lockdowns in the wake of the coronavirus disease-2019, and then from March to August 2021. The sample comprised children aged <2 years. Data was analysed using SPSS 25. RESULTS: Of the 330 children, 210(63.6%) were boys, and 120(36.4%) were girls, and all 330(100%) were located in rural areas. First-phase data showed that the maximum coverage rate of immunisation was 258(78.2%) noted in OPV1(Oral Polio Vaccine) Penta1(Pentavalent vaccine), PCV10-1 (Pneumococcal pneumonia) and Rota 1(Rota Vaccine), and the least vaccination rate was 68.2% for Measle-1. In the second phase, 23% incline was noted in Measles-2 vaccination, followed by 16.3% in OPV2, Penta 2, PCV10-2 and Rota 2, 16% in Measles-1, 14% in OPV-3, Penta-3, PCV10-3, Rota-3 and IPV, 11.5% in OPV-1, Penta-1, PCV10-1, and Rota-1, and 10.6% in OPV-0 and BCG-0. CONCLUSIONS: Immunisation programme was affected by lockdowns during the active phase of the coronavirus disease-2019 pandemic.