After the World Health Organisation declared India a polio free nation in 2014, the government had warned that wild polio continues to thrive in India’s neighbourhood – in Pakistan and Afghanistan – so it has to remain vigilant.
Owing to the threat of polio being imported from neighbouring countries, India introduced injectable inactivated polio vaccine for children below one year of age last year. It also switched to bivalent oral polio vaccine (OPV) from the trivalent version this April. The trivalent vaccine contains all three types of live polio viruses while bivalent version contains only type 1 and type 3 viruses. The type 2 virus in the trivalent version was blamed for polio infections more than five years ago, hence the change.
Several instances of suspected polio cases emerged after India was declared polio-free. In June this year, a strain of the virus was found in samples of sewage water in Hyderabad. The strain found was a vaccine derived polio-virus or VDPV. The government later released a statement saying the country has eradicated the wild polio virus and the last case was seen on January 13, 2011.
A few days later, a 6-year-old child was detected with potential virus, suspected to be wild polio, in UP’s Balrampur district in June. The World Health Organisation later clarified that there is no case from wild polio in Balrampur and the detection of a rare strain of the crippling disease is not unusual. It also said that all countries in the South-East Asia Region continue to maintain a very high vigil for poliovirus detection.
After the polio-free status of India came under fire, the government released a statement stating that the detection of vaccine derived polio virus does not change the polio free status. It only indicates the robustness of the surveillance system. The World Health Organisation also maintained that amid concerns over resurfacing of polio cases, there is no threat to the polio-free status of India.
Refuting media reports that around 200 samples have tested positive to polio-like symptoms in Uttar Pradesh, the Health Ministry in June asserted that its test has found all these cases negative and India remains polio free for the fourth consecutive year.