THE frequent emergence of vaccine-derived polio virus type-2, or VDPV2, cases in the country has led to complex challenges for the health authorities. Most of these cases have surfaced in KP where, in addition to an overall surge in polio cases this year, there has been violence against polio teams. Since the second half of 2019, a total of 31 VDPV2 cases have surfaced — 22 in 2019 and nine in 2020 so far. This is a matter of great concern because the type 2 virus was believed to have been eradicated globally and WHO had discontinued the vaccine for it in Pakistan some years ago. The oral vaccine that is now administered to children in the country only contains antigens for the P1 and P3 strains. According to WHO, comatose virus contained in oral polio vaccines that keeps circulating in under-immunised communities for at least a year causes vaccine-derived polio. In this instance, the VDPV2 cases are believed to have been caused by a mutation in the type 2 virus. It is unclear how the virus resurfaced. But the authorities should take note that it has become a threat to global anti-polio efforts.

Meanwhile, vaccine-derived polio cases have also surfaced in several countries of West Africa, such as Congo and Nigeria (which was set to be declared polio-free last year); as well as in the Philippines, Malaysia and China. Some experts have suggested that malnutrition and poor sanitation are a major contributing factor in the resurfacing of VDPV2 cases. As the health authorities prepare to take up the growing polio challenge, they must also identify the gaps in the anti-polio programme and analyse how they can boost eradication efforts, which only some years ago had brought down the number of cases in the country substantially. Prioritising polio awareness among communities and neighbourhoods and providing more security for vaccinators to get the campaign back on track would be a good beginning.

Published in Dawn, March 1st, 2020