Regulatory Aspects of Sabin Type 2 Withdrawal From Trivalent Oral Poliovirus Vaccine: Process and Lessons Learned

[New oral polio vaccine: A turning point for the global polio eradication initiative?]

Launched in 1988, the Global Polio Eradication Initiative (GPEI) aims to eradicate polioviruses, which are the etiologic agents of poliomyelitis. Coordinated by the World Health Organization, this program relies on two pillars: mass vaccination campaigns that target children and active surveillance of the virus circulation. The GPEI has led to the eradication of two out of three serotypes of wild polioviruses and to the containment of the last serotype in two countries.Two polio vaccines exist: the injectable vaccine and the oral one. Both induce an efficient protection against poliomyelitis, but only the oral vaccine is able to stop poliovirus transmission chains. Therefore, the oral vaccine is essential to contain polioviruses and, finally, to eradicate them. In some contexts where the vaccine coverage is not sufficient, the attenuated strains contained in the oral vaccine can circulate for months and recover a pathogenic phenotype through genetic drift. In order to prevent this phenomenon, a new vaccine strain has been developed through genetic engineering: it has been designed to be as immunogenic as the historical vaccine strain, but more genetically stable to prevent the loss of its attenuation determinants. After being evaluated in vitro and through clinical trials, the novel strain has been rolled out in several African countries and in Tajikistan in 2021.

Worldwide Assessment of Low- and Middle-Income Countries' Regulatory Preparedness to Approve Medical Products During Public Health Emergencies

Background: Regulatory preparedness for public health emergencies is critical. However, responses to past emergencies, such as the 2009 H1N1 influenza pandemic and medical product shortages, have revealed sizable gaps in countries' regulatory capacity and preparedness. A systematic analysis of the regulatory preparedness of countries around the world has not yet been performed. The purpose of this study was to analyze and document the current regulatory preparedness status, highlight the related gaps and challenges in order to propose strategic, harmonized, and sustainable regulatory solutions to improve future responses to public health emergencies.

Methods: From 2016 to 2020, we used the World Health Organization (WHO)'s Global Benchmarking Tool (GBT), a standardized instrument for identifying national regulatory authorities' strengths and gaps, to analyze the regulatory preparedness of 84 Member States, 95% of which were low- or middle-income countries. We analyzed whether participating Member States had not implemented, displayed ongoing implementation, had partially implemented, or had fully implemented 10 of the GBT's 268 sub-indicators most relevant to regulatory preparedness for public health emergencies.

Findings: Only 10 Member States (12%) that underwent benchmarking had fully implemented all 10 sub-indicators related to regulatory preparedness for public health emergencies; 34 (40%) had fully implemented ≥50% of the emergency sub-indicators, and 20 (24%) had not fully implemented any of the sub-indicators. With regard to individual sub-indicators, regulatory preparedness ranged from 19 Member States (23%) fully implementing reliance on clinical trial decisions of others to 45 (59%) fully implementing legal provisions to fast-track (or expedite) marketing authorization applications.

Interpretation: Many WHO Member States have limited regulatory preparedness for a public health emergency. Strengthening regulatory systems and promoting Good Regulatory Practices and reliance in these countries, to enable efficient response to emergencies, should be a global health priority.

Addressing the Challenges and Opportunities of the Polio Endgame: Lessons for the Future

The Global Commission for the Certification of the Eradication of Poliomyelitis certified the eradication of type 2 poliovirus in September 2015, making type 2 poliovirus the first human pathogen to be eradicated since smallpox. The eradication of type 2 poliovirus, the absence of detection of type 3 poliovirus worldwide since November 2012, and cornering type 1 poliovirus to only a few geographic areas of 3 countries has enabled implementation of the endgame of polio eradication which calls for a phased withdrawal of oral polio vaccine beginning with the type 2 component, introduction of inactivated poliovirus vaccine, strengthening of routine immunization in countries with extensive polio resources, and initiating activities to transition polio resources, program experience, and lessons learned to other global health initiatives. This supplement focuses on efforts by global partners to successfully launch polio endgame activities to permanently secure and sustain the enormous gains of polio eradication forever.

Considerations for the Full Global Withdrawal of Oral Polio Vaccine After Eradication of Polio

Eliminating the risk of polio from vaccine-derived polioviruses is essential for creating a polio-free world, and eliminating that risk will require stopping use of all oral polio vaccines (OPVs) once all types of wild polioviruses have been eradicated. In many ways, the experience with the global switch from trivalent OPV (tOPV) to bivalent OPV (bOPV) can inform the eventual full global withdrawal of OPV. Significant preparation will be needed for a thorough, synchronized, and full withdrawal of OPV, and such preparation would be aided by setting a reasonably firm date for OPV withdrawal as far in advance as possible, ideally at least 24 months. A shorter lead time would provide valuable flexibility for decisions about when to stop use of OPV in the context of uncertainty about whether or not all types of wild polioviruses had been eradicated, but it might increase the cost of OPV withdrawal.