[New oral polio vaccine: A turning point for the global polio eradication initiative?]
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ABSTRACT:
SUBMITTER: Bessaud M
PROVIDER: S-EPMC9283809 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Despite a strong global commitment, polio eradication efforts continue now more than 30 years after the 1988 World Health Assembly resolution that established the Global Polio Eradication Initiative (GPEI), and 20 years after the original target of the year 2000. Prior health economic analyses estimated incremental net benefits of the GPEI of 40-50 billion in 2008 U.S. dollars (US$2008, equivalent to 48-59 billion US$2019), assuming the achievement of polio eradication by 2012. Given the delays in achieving polio eradication and increased costs, we performed an updated economic analysis of the GPEI using an updated integrated global model, and considering the GPEI trajectory as of the beginning of 2020. Applying similar methods and assuming eradication achievement in 2023, we estimate incremental net benefits of the GPEI of 28 billion US$2019, which falls below the prior estimate. Delays in achieving polio eradication combined with the widescale introduction of relatively expensive inactivated poliovirus vaccine significantly increased the costs of the GPEI and make it less cost-effective, although the GPEI continues to yield expected incremental net benefits at the global level when considered over the time horizon of 1988-2029. The overall health and financial benefits of the GPEI will depend on whether and when the GPEI can achieve its goals, when eradication occurs, the valuation method applied, and the path dependence of the actions taken. Reduced expected incremental net benefits of the GPEI and the substantial economic impacts of the COVID-19 pandemic pose large financial risks for the GPEI.
| S-EPMC7894996 | biostudies-literature
Project description:The oral polio vaccine (OPV) contains live-attenuated polioviruses that induce immunity by causing low virulence infections in vaccine recipients and their close contacts. Widespread immunization with OPV has reduced the annual global burden of paralytic poliomyelitis by a factor of 10,000 or more and has driven wild poliovirus (WPV) to the brink of eradication. However, in instances that have so far been rare, OPV can paralyze vaccine recipients and generate vaccine-derived polio outbreaks. To complete polio eradication, OPV use should eventually cease, but doing so will leave a growing population fully susceptible to infection. If poliovirus is reintroduced after OPV cessation, under what conditions will OPV vaccination be required to interrupt transmission? Can conditions exist in which OPV and WPV reintroduction present similar risks of transmission? To answer these questions, we built a multi-scale mathematical model of infection and transmission calibrated to data from clinical trials and field epidemiology studies. At the within-host level, the model describes the effects of vaccination and waning immunity on shedding and oral susceptibility to infection. At the between-host level, the model emulates the interaction of shedding and oral susceptibility with sanitation and person-to-person contact patterns to determine the transmission rate in communities. Our results show that inactivated polio vaccine (IPV) is sufficient to prevent outbreaks in low transmission rate settings and that OPV can be reintroduced and withdrawn as needed in moderate transmission rate settings. However, in high transmission rate settings, the conditions that support vaccine-derived outbreaks have only been rare because population immunity has been high. Absent population immunity, the Sabin strains from OPV will be nearly as capable of causing outbreaks as WPV. If post-cessation outbreak responses are followed by new vaccine-derived outbreaks, strategies to restore population immunity will be required to ensure the stability of polio eradication.
| S-EPMC5942853 | biostudies-literature
Project description:The CORE Group Polio Project (CGPP) has contributed to polio eradication by successfully engaging civil society, particularly the non-governmental organization (NGO) community. This engagement, which began with a grant from the U.S. Agency for International Development in 1999, has contributed to improvements in routine immunization programs, polio campaign quality, and surveillance for acute flaccid paralysis in many challenging geographic areas. The CGPP has worked closely with polio eradication partners in a collaborative and supportive role. The CGPP has focused largely on high-risk areas with marginalized or hard-to-reach populations where health systems and immunization programs have also been weak and where transmission of poliovirus had not been stopped. The CGPP has engaged local civic leaders and communities in ways to complement top-down vertical efforts of ministries of health and other partners in the Global Polio Eradication Initiative. The CGPP has developed innovative strategies to detect cases using community-based surveillance, promoted independent campaign monitoring, established cross-border initiatives, and developed a strong and creative cadre of community mobilizers to track missed children and deliver behavior change education. Many of the innovations and approaches that the CGPP helped to develop are now being replicated by governments and international agencies to tackle other public health priorities in underserved and marginalized communities around the world. This article is the first in a series of articles describing the work of the CGPP. Because the article describes the work of more than 40 NGOs in 11 countries over 20 years, it provides only an overview, leaving many important details and variations of the CGPP's work to be described elsewhere, including in other articles included in this series.
| S-EPMC6776098 | biostudies-literature
Project description:BackgroundImmunization programs have leveraged decades of research to maximize oral polio vaccine (OPV) response. Moving toward global poliovirus eradication, the WHO recommended phased OPV-to-IPV replacement on schedules in 2012. Using the MAL-ED prospective birth cohort data, we evaluated the influence of early life exposures impacting OPV immunization by measuring OPV response for serotypes 1 and 3.MethodsPolio neutralizing antibody assays were conducted at 7 and 15?months of age for serotypes 1 and 3. Analyses were conducted on children receiving ?3 OPV doses (n?=?1449). History of vaccination, feeding patterns, physical growth, home environment, diarrhea, enteropathogen detection, and gut inflammation were examined as risk factors for non-response [Log2(titer)?<?3] and Log2(titer) by serotype using multivariate regression.FindingsSerotype 1 seroconversion was significantly higher than serotype 3 (96.6% vs. 89.6%, 15?months). Model results indicate serotypes 1 and 3 failure was minimized following four and six OPV doses, respectively; however, enteropathogen detection and poor socioeconomic conditions attenuated response in both serotypes. At three months of age, bacterial detection in stool reduced serotype 1 and 3 Log2 titers by 0.34 (95% CI 0.14-0.54) and 0.53 (95% CI 0.29-0.77), respectively, and increased odds of serotype 3 failure by 3.0 (95% CI 1.6-5.8). Our socioeconomic index, consisting of Water, Assets, Maternal education, and Income (WAMI), was associated with a 0.79 (95% CI 0.15-1.43) and 1.23 (95% CI 0.34-2.12) higher serotype 1 and 3 Log2 titer, respectively, and a 0.04 (95% CI 0.002-0.40) lower odds of serotype 3 failure. Introduction of solids, transferrin receptor, and underweight were differentially associated with serotype response. Other factors, including diarrheal frequency and breastfeeding practices, were not associated with OPV response.InterpretationUnder real-world conditions, improved vaccination coverage and socio-environmental conditions, and reducing early life bacterial exposures are key to improving OPV response and should inform polio eradication strategies.
| S-EPMC6325791 | biostudies-literature
Project description:BackgroundQuantifying interference of maternal antibodies with immune responses to varying dose schedules of inactivated polio vaccine (IPV) is important for the polio endgame as IPV replaces oral polio vaccine (OPV).MethodsType 2 poliovirus humoral and intestinal responses were analyzed using pre-IPV type 2 seropositivity as proxy for maternal antibodies from 2 trials in Latin America. Infants received 1 or 2 doses of IPV in sequential IPV-bivalent oral polio vaccine (bOPV) or mixed bOPV-IPV schedules.ResultsAmong infants vaccinated with bOPV at age 6, 10, and 14 weeks of age and IPV at 14 weeks, those with type 2 pre-IPV seropositivity had lower seroprotection rates than seronegative infants at 4 weeks (92.7% vs 83.8%; difference, 8.9% [95% confidence interval, 0.6%-19.9%]; n = 260) and 22 weeks (82.7% vs 60.4%; difference, 22.3 [12.8%-32.4%]; n = 481) post-IPV. A second IPV at age 36 weeks resulted in 100% seroprotection in both groups. Among infants vaccinated with 1 IPV at age 8 weeks followed by 2 doses of bOPV, pre-IPV type 2-seropositive infants had lower seroprotection at age 28 weeks than those who were seronegative (93.0% vs 73.9%; difference, 19.6% [95% confidence interval, 7.3%-29.4%]; n = 168). A second dose of IPV at 16 weeks achieved >97% seroprotection at age 24 or 28 weeks, regardless of pre-IPV status. Poliovirus shedding after challenge with monovalent OPV, serotype 2, was higher in pre-IPV seropositive infants given sequential IPV-bOPV. No differences were observed in the mixed bOPV-IPV schedule.ConclusionsThe presence of maternal antibody is associated with lower type 2 post-IPV seroprotection rates among infants who receive a single dose of IPV. This impact persists until late in infancy and is overcome by a second IPV dose.
| S-EPMC6206111 | biostudies-literature
Project description:Worldwide efforts to eradicate polio caused a tipping point in polio vaccination strategies. A switch from the oral polio vaccine, which can cause circulating and virulent vaccine derived polioviruses, to inactivated polio vaccines (IPV) is scheduled. Moreover, a manufacturing process, using attenuated virus strains instead of wild-type polioviruses, is demanded to enhance worldwide production of IPV, especially in low- and middle income countries. Therefore, development of an IPV from attenuated (Sabin) poliovirus strains (sIPV) was pursued. Starting from the current IPV production process based on wild type Salk strains, adaptations, such as lower virus cultivation temperature, were implemented. sIPV was produced at industrial scale followed by formulation of both plain and aluminium adjuvanted sIPV. The final products met the quality criteria, were immunogenic in rats, showed no toxicity in rabbits and could be released for testing in the clinic. Concluding, sIPV was developed to manufacturing scale. The technology can be transferred worldwide to support post polio-eradication biosafety goals.
| S-EPMC3861478 | biostudies-other
Project description:There are currently huge efforts by the World Health Organization and partners to complete global polio eradication. With the significant decline in poliomyelitis cases due to wild poliovirus in recent years, rare cases related to the use of live-attenuated oral polio vaccine assume greater importance. Poliovirus strains in the oral vaccine are known to quickly revert to neurovirulent phenotype following replication in humans after immunisation. These strains can transmit from person to person leading to poliomyelitis outbreaks and can replicate for long periods of time in immunodeficient individuals leading to paralysis or chronic infection, with currently no effective treatment to stop excretion from these patients. Here, we describe an individual who has been excreting type 2 vaccine-derived poliovirus for twenty eight years as estimated by the molecular clock established with VP1 capsid gene nucleotide sequences of serial isolates. This represents by far the longest period of excretion described from such a patient who is the only identified individual known to be excreting highly evolved vaccine-derived poliovirus at present. Using a range of in vivo and in vitro assays we show that the viruses are very virulent, antigenically drifted and excreted at high titre suggesting that such chronic excreters pose an obvious risk to the eradication programme. Our results in virus neutralization assays with human sera and immunisation-challenge experiments using transgenic mice expressing the human poliovirus receptor indicate that while maintaining high immunisation coverage will likely confer protection against paralytic disease caused by these viruses, significant changes in immunisation strategies might be required to effectively stop their occurrence and potential widespread transmission. Eventually, new stable live-attenuated polio vaccines with no risk of reversion might be required to respond to any poliovirus isolation in the post-eradication era.
| S-EPMC4552295 | biostudies-literature
Project description:Poliomyelitis has nearly been eradicated through the efforts of the World Health Organization's Global Eradication Initiative raising questions on containment of the virus after it has been eliminated in the wild. Most manufacture of inactivated polio vaccines currently requires the growth of large amounts of highly virulent poliovirus, and release from a production facility after eradication could be disastrous; WHO have therefore recommended the use of the attenuated Sabin strains for production as a safer option although it is recognised that they can revert to a transmissible paralytic form. We have exploited the understanding of the molecular virology of the Sabin vaccine strains to design viruses that are extremely genetically stable and hyperattenuated. The viruses are based on the type 3 Sabin vaccine strain and have been genetically modified in domain V of the 5' non-coding region by changing base pairs to produce a cassette into which capsid regions of other serotypes have been introduced. The viruses give satisfactory yields of antigenically and immunogenically correct viruses in culture, are without measurable neurovirulence and fail to infect non-human primates under conditions where the Sabin strains will do so.
| S-EPMC4699825 | biostudies-other
Project description:Wild polioviruses still remain endemic in three countries (Afghanistan, Pakistan, and Nigeria) and re-emergency of wild polio has been reported in previously polio-free countries. Environmental surveillance has been used as a supplementary tool in monitoring the circulation of wild poliovirus (PVs) and/or vaccine-derived PVs even in the absence of acute flaccid paralysis cases. This study aimed to monitor the presence of polioviruses in wastewater samples collected at one wastewater treatment plant located in the municipality of Rio de Janeiro, Brazil. From December 2011 to June 2012 and from September to December 2012, 31 samples were collected and processed. RD and L20B cell cultures were able to isolate PVs and non-polio enteroviruses in 27/31 samples. Polioviruses were isolated in eight samples (type 1 Sabin = 1, type 2 Sabin = 5, and type 3 Sabin = 2). Vaccine-derived polioviruses were not detected nor evidence of recombination with other PVs or non-polio enterovirus serotypes were observed among the isolates. The Sabin-related serotypes 2 and 3 presented nucleotide substitutions in positions associated with the neurovirulent phenotype at the 5'-UTR. Changes in important Amino acid residues at VP1 were also observed in the serotypes 2 and 3. Environmental surveillance has been used successfully in monitoring the circulation of PVs and non-polio enteroviruses and it is of crucial importance in the final stages of the WHO global polio eradication initiative. Our results show the continuous circulation of Sabin-like PVs and non-polio enteroviruses in the analyzed area during the study period.
| S-EPMC4752579 | biostudies-literature
Project description:ObjectivesTo 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.DesignA cross-sectional survey with closed and open-ended questions.SettingsSurvey 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.ParticipantsIndividuals (n=802) with ≥12 months of experience implementing surveillance objective of the GPEI between 1988 and 2019.Main outcome measures and methodsQuantitative 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.ResultsOverall, 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.ConclusionsProgramme 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.
| S-EPMC9109099 | biostudies-literature