Polio endgame: the global switch from tOPV to bOPV

ABSTRACT

Globally, polio cases have reached an all-time low, and type 2 poliovirus (one of three) is eradicated. Oral polio vaccine (OPV) has been the primary tool, however, in rare cases, OPV induces paralysis. In 2013, the World Health Assembly endorsed the phased withdrawal of OPV and introduction of inactivated poliovirus vaccine (IPV) into childhood routine immunization schedules. Type 2 OPV will be withdrawn through a globally synchronized “switch” from trivalent OPV (all three types) to bivalent OPV (types 1 and 3). The switch will happen in 155 OPV-using countries between April 17^th and May 1^st, 2016. Planned activities to reduce type 2 outbreak risks post-switch include the following: tOPV campaigns to increase type 2 immunity prior to the switch, monovalent OPV2 stockpiling to respond to outbreaks should they occur, containment of both wild and vaccine type 2 viruses, enhanced acute flaccid paralysis (AFP) and environmental surveillance, outbreak response protocols, and ensured access to IPV and bivalent OPV.

KEYWORDS:

• polio
• poliomyelitis
• eradication
• immunization
• oral polio vaccine
• inactivated polio vaccine
• switch

Financial and competing interests disclosure

J Garon, K Seib and W Orenstein are supported by the Bill & Melinda Gates Foundation under Work Order 23848. M Patel is supported by grant OPP1095024. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Notes

1. Focus countries include Angola, Afghanistan, Chad, DR Congo, Ethiopia, India, Nigeria, Pakistan, Somalia and South Sudan [57].