Stopping Vaccine-Derived Polioviruses – January 2016 press release from the World Health Organization

Stopping Vaccine-Derived Polioviruses – January 2016 press release from the World Health Organization

In just four months’ time, the world will embark on one of the most ambitious globally synchronized projects in the history of vaccines.

April 2016 will see 155 countries and territories stop using the trivalent oral polio vaccine (OPV) and switch to the bivalent version of the vaccine, in a single two-week period. This will have an important impact on progress towards achieving the eradication of all polioviruses worldwide.

In 2015, more countries were infected by vaccine-derived polioviruses (VDPVs) than wild polio (WPV). VDPVs are very rare strains of polio that can mutate from the weakened poliovirus in the oral polio vaccine when levels of immunization are very low, allowing the vaccine virus to circulate amongst unprotected children for an extended period of time.
 
With the eradication of wild poliovirus type 2, the type 2 component of the oral polio vaccine is no longer needed. This is good news for children and the polio eradication program, as the type 2 component of the oral polio vaccine has caused 90 % of circulating VDPV outbreaks in recent years. By switching from the trivalent vaccine (which contains protection against all three strains) to the bivalent vaccine which no longer contains type 2, we therefore withdraw the main cause of VDPVs and take the program an important step forward towards eradication.

With the world closer to poliovirus eradication than ever, it is vital immunization activities are strengthened and coverage is maximized.
 
Vigilance remains essential. The upcoming switch is vital for the cessation of cVDPV2 and will mark a milestone in the polio eradication.