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

Area of Science:

• * Global Health
• * Vaccinology
• * Epidemiology

Background:

• * The polio endgame strategy aims to eliminate Sabin vaccines due to circulating vaccine-derived poliovirus (cVDPV) risks.
• * Following the wild poliovirus type 2 eradication and the switch from tOPV to bOPV, monovalent type 2 oral poliovirus vaccine (mOPV2) is used for cVDPV2 outbreak response.
• * The use of mOPV2 paradoxically risks reintroducing live poliovirus, necessitating stringent management.

Purpose of the Study:

• * To evaluate the performance of mOPV2 vaccine management in outbreak response activities post-tOPV to bOPV switch.
• * To identify challenges and lessons learned to improve future response strategies and technical guidance.
• * To highlight the importance of robust vaccine management for minimizing VDPV2 emergence risks.

Main Methods:

• * Review of mOPV2 vaccine management practices across various outbreak response campaigns.
• * Analysis of performance in vaccine accountability and stock management.
• * Qualitative assessment of challenges and lessons learned during implementation.

Main Results:

• * Significant variation in mOPV2 vaccine management performance across different countries and campaigns.
• * Major gaps identified in vaccine accountability, with numerous unaccounted vials.
• * Insufficient attention to mOPV2 management, particularly during the early stages of implementation.

Conclusions:

• * Enhanced focus on mOPV2 vaccine management is critical for public health programs to prevent further VDPV2 emergence.
• * Lessons learned should inform improved technical guidance and future response activities for VDPV2 outbreaks.
• * Effective stock management strategies for mOPV2 can inform practices for other vaccines requiring strict containment and withdrawal.