Monovalent type 2 OPV (mOPV2) management in the field: Interventions and lessons learned.

The polio endgame strategy calls for ending the use of and removal of all Sabin vaccines globally given the risks of generation and spread of cVDPVs. With the successful eradication of wild poliovirus type 2 in 2015, the process of removing type 2 Sabin vaccines began with the switch from tOPV to bOPV across national vaccination programs. Following the tOPV to bOPV switch in April/May 2016, monovalent type 2 OPV (mOPV2) has been put into use in response to detected cVDPV2 polioviruses outbreaks. Between 31 May 2016 and 30 Jun 2020, 453 million doses of mOPV2 were provided to 21 countries to conduct 235 campaigns to respond to cVDPV2 outbreaks and high-risk events. However, the use of this vaccine paradoxically reintroduces live attenuated type 2 poliovirus into the populations and the environment, therefore, poses a risk for the emergence of new VDPV2s. Thus, it is critical to carefully and appropriately manage all in-country mOPV2 stocks utilized in outbreak response to minimize this risk. In this article, we examine the performance of mOPV2 vaccine management utilized for various outbreak responses after the switch.We present the major challenges faced and the lessons learned, to improve technical guidance and future response activities. Performance varied significantly across countries in terms of each of the activity areas evaluated. There were major gaps, especially in terms of vaccine accountability, and in many instances large numbers of vials went unaccounted presenting additional risk for further VDPV2 emergences. We have shown that especially at the beginning of implementation, insufficient attention has been given to mOPV2 vaccine management. Enhanced focus on mOPV2 vaccine management in line with the lessons learned presented in this paper should be a priority for public health programs and countries to consider and adapt in future VDPV2 responses as well as potential future activities associated with eventual complete withdrawal & cessation of OPV.These experiences can also be extended to other vaccines for which strict stock management and containment measures are required.

The global switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV): facts, experiences and lessons learned from the south-south zone; Nigeria, April 2016.

BACKGROUND: The globally synchronized switch from trivalent Oral Polio Vaccine (tOPV) to bivalent Oral Polio Vaccine (bOPV) took place in Nigeria on April 18th 2016. The country is divided into six geopolitical zones. This study reports the experiences and lessons learned from the switch process in the six states that make up Nigeria's south-south geopolitical zone. METHODS: This was a descriptive retrospective review of Nigeria's switch plan and structures used for implementing the tOPV-bOPV switch in the south-south zone. Nigeria's National Polio Emergency Operation Centre (NPEOC) protocols, global guidelines and reports from switch supervisors during the switch were used to provide background information for this study. Quantitative data were derived from reviewing switch monitoring and validation documents as submitted to the NPEOC RESULTS: The switch process took place in all 3078 Health Facilities (HFs) and 123 Local Government Areas (LGAs) that make up the six states in the zone. A total of $139,430 was used for this process. The 'healthcare personnel' component received the highest budgetary allocation (59%) followed by the 'logistics' component (18%). Akwa Ibom state was allocated the highest number of healthcare personnel and hence received the most budgetary allocation compared to the six states (total healthcare personnel = 458, total budgetary allocation = $17,428). Validation of the switch process revealed that eight HFs in Bayelsa, Cross-River, Edo and Rivers states still possessed tOPV in cold-chain while six HFs in Cross-River and Rivers states had tOPV out of cold-chain but without the 'do not use' sticker. Akwa-Ibom was the only state in the zone to have bOPV and Inactivated Polio Vaccine (IPV) available in all its HFs monitored. CONCLUSION: The Nigerian tOPV-bOPV switch was successful. For future Oral Polio Vaccine (OPV) withdrawals, implementation of the switch plan would be more feasible with an earlier dissemination of funds from global donor organizations, which would greatly aid timely planning and preparations. Increased budgetary allocation to the 'logistics' component to accommodate unexpected hikes in transportation prices and the general inefficiencies with power supply in the country is also advised.