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The Global Polio Eradication Initiative (GPEI) has seen significant progress since it began in 1988, largely due to the worldwide use of oral poliovirus vaccine (OPV). In order to achieve polio eradication the global cessation of OPV is necessary because OPV contains live attenuated poliovirus, which in rare circumstances could re-gain wild poliovirus (WPV) characteristics with potential to establish transmission. The GPEI endgame strategy for the period 2013-2018 recommends the globally synchronised sequential cessation of the Sabin strains contained in the OPV, starting with type 2 Sabin. The withdrawal of Sabin type 2 took place in April 2016, with the introduction of at least one dose of inactivated poliovirus vaccine (IPV) as a risk mitigation strategy. The introduction of IPV into 126 countries since 2013 has required a rapid scale-up of IPV production by the two manufacturers supplying the global public sector market. This scale-up has been fraught with challenges, resulting in reductions of 40-50% of initial supply commitments. Consequently, 22 countries will not be supplied until 2018, and another 23 countries will experience serious stock-outs. In the last decade repeated calls-for-action were made to the global community to invigorate their vision and investment in developing "new poliovirus vaccines" including the development of IPV from less-virulent strains, such as Sabin-IPV (S-IPV). The conventional Salk-IPV production is limited to high-income industrialized-country manufacturers due to the containment requirements (i.e., high sanitation, low force-of-poliovirus-infection, and high population immunity). The use of Sabin strains in the production of S-IPV carries a lower biosafety risk, and was determined to be suitable for production in developing countries, expanding the manufacturing base and making IPV more affordable and accessible in the long term. Significant progress in the S-IPV has been made since 2006. S-IPV is now licensed as S-IPV in Japan and as standalone S-IPV in China, demonstrating the feasibility of this vaccine. In addition, production process improvements can further reduce the cost of production. The latter are critical to the economic success of this vaccine in the global market. We summarize the progress made to date in S-IPV technology, the scientific data and economic evidence in support of S-IPV development., (Copyright © 2016 International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.)

Monitoring the quality of supplementary immunization activities (SIAs) is a key tool for polio eradication. Regular monitoring data, however, are often unreliable, showing high coverage levels in virtually all areas, including those with ongoing virus circulation. To address this challenge, lot quality assurance sampling (LQAS) was introduced in 2009 as an additional tool to monitor SIA quality. Now used in 8 countries, LQAS provides a number of programmatic benefits: identifying areas of weak coverage quality with statistical reliability, differentiating areas of varying coverage with greater precision, and allowing for trend analysis of campaign quality. LQAS also accommodates changes to survey format, interpretation thresholds, evaluations of sample size, and data collection through mobile phones to improve timeliness of reporting and allow for visualization of campaign quality. LQAS becomes increasingly important to address remaining gaps in SIA quality and help focus resources on high-risk areas to prevent the continued transmission of wild poliovirus., (© Crown copyright 2014.)

Background: To assess the quality of supplementary immunization activities (SIAs), the Global Polio Eradication Initiative (GPEI) has used cluster lot quality assurance sampling (C-LQAS) methods since 2009. However, since the inception of C-LQAS, questions have been raised about the optimal balance between operational feasibility and precision of classification of lots to identify areas with low SIA quality that require corrective programmatic action., Methods: To determine if an increased precision in classification would result in differential programmatic decision making, we conducted a pilot evaluation in 4 local government areas (LGAs) in Nigeria with an expanded LQAS sample size of 16 clusters (instead of the standard 6 clusters) of 10 subjects each., Results: The results showed greater heterogeneity between clusters than the assumed standard deviation of 10%, ranging from 12% to 23%. Comparing the distribution of 4-outcome classifications obtained from all possible combinations of 6-cluster subsamples to the observed classification of the 16-cluster sample, we obtained an exact match in classification in 56% to 85% of instances., Conclusions: We concluded that the 6-cluster C-LQAS provides acceptable classification precision for programmatic action. Considering the greater resources required to implement an expanded C-LQAS, the improvement in precision was deemed insufficient to warrant the effort., (Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Since the resolution of the World Assembly in 1988 to eradicate polio globally, substantial progress toward this target has been achieved, but the final goal remains elusive. India and other tropical developing countries present a unique challenge because of the much lower oral poliovirus vaccine (OPV) immunogenicity compared to industrialized countries, both in terms of humoral and mucosal immunity. To overcome this challenge, further research is needed to elucidate the causes for the suboptimal OPV immunogenicity, better defining the optimal vaccine schedules and delivery strategies, developing and evaluating adjuvants to boost OPV immunogenicity, and improving the methods for directly measuring mucosal immunity., (Copyright © 2011 World Health Organization. Published by Elsevier Ltd.. All rights reserved.)