WHO plans strategy shift with polio vaccines

Eyeing an world free from all types of polio-virus, the World Health Organisation plans a strategy shift, in which, an inactivated polio-virus vaccine (IPV) injection will be used in tandem with the existing oral polio vaccine to have the maximum efficiency of the public health campaign and eliminate all the three types of polio virus.

If everything goes according to the plan – and that’s a big “if” – the WHO might recommend the introduction of IPV in India by 2014, Bruce Aylward, Assistant Director General in charge of the Polio Programme at the WHO said on the sidelines of two-day Polio Summit.

The introduction of IPV will be preceded by a global switch from trivalent polio vaccine needed to tackle P1, P2 and P3 strains of the virus to a bivalent vaccine responsible for taming only the P1 and P3 strains. The IPV will be for P2.

Choice of the polio vaccine – IPV versus OPV – remained a matter of intense debate
among public health researchers and doctors for many decades. The IPV was expensive but at the same time provided a lasting solution.

India and other developing countries, however, went ahead with the OPV as the cost was low. Subsequently they developed the strategy of multiple rounds of vaccination with OPV.

“One dose of IPV costs three dollars while one dose of OPV costs 15 cents. The IPV was never adapted for developing countries,” Aylward, said, adding that the plan eventually is to give one dose of IPV for type-2 polio viruses in the routine immunisation programme.
The last case of type-2 polio virus happened in Aligarh in Uttar Pradesh in 1999. But since the trivalent polio vaccine is still in use, public health officials apprehend that type-2 virus might return from the wild with vengeance. The solution, they said, was to include IPV in the public health campaign.

But before introduction, the cost of the IPV has to be reduced substantially to make it acceptable in the developing world. One option, Aylward said, was to convert the virus strain used in OPV (Sabin) to an IPV. However the efficacy of the Sabin IPV against P-2 in India has to be evaluated first.