Around 1.5 lakh kids in UP, Maharashtra and Telangana have received polio vaccines (OPV) contaminated with poliovirus type 2. A strand that has been pronounced ‘eradicated’. The breach is serious. Poliomyelitis is a highly contagious viral disease that can maim, paralyze or even kill children. And now, poliovirus type 2 is back in the environment and there is a small possibility that the virus might cause polio—if not in a child who received the dose (a tiny but ever-present risk), then in the wider population of kids born after 2016 who have not been inoculated against polio type 2. The world, and India with it, stopped vaccinating children against type 2 in April 2016.

“Among non-immune children, there is the possibility of some getting infected from the vaccinated children,” said T Jacob John, a polio researcher with the Christian Medical College in Vellore. “Very low probability of that happening, but in case it happens, then the result will be a polio outbreak.”

Experts say this situation could’ve been entirely avoided if India’s Universal Immunisation Programme (UIP) predominantly administered an injectable polio vaccine to kids, rather than the oral one. India does not because there’s a worldwide shortage of injectable vaccines (the “inactivated polio vaccine” or IPV) that will ease only in 2023—the result of a lack of foresight on the part of global health authorities.

The global community has learned its lesson on polio,” said Raj Shankar Ghosh, deputy director of vaccine delivery at the Bill and Melinda Gates Foundation. “No one expected the supply shortage’.

Four strategies for polio immunisation

These were endorsed by WHO and followed by India:
National immunisation programme
Surveillance of any child who complains of sudden weakness/paralysis
Mop-up: stepping up inoculations if a case is reported
Pulse polio program

And so, India is mostly giving out oral vaccines and rationing its limited IPV supplies. Kids are getting fractional doses on a schedule that is relatively less effective, said Vipin Vashishtha, a paediatrician and polio expert at Mangla Hospital and Research Center in Bijnor, Uttar Pradesh. And coverage is low—only 47% of Indian kids got IPV last year, according to the World Health Organization.

“If there is a resurgence or appearance of, for example, vaccine-derived type 2 [polio], with this type of schedule, you may have compromised efficacy,” said Vashishtha. “Population immunity may not be that great.”

If polio type 2 manifests in the community, it would be a serious setback to the global and India’s polio eradication efforts. India’s last wild polio case was in 2011, and it was certified polio-free in March 2014. The last case of polio type 2 was seen in 2002.

The government and WHO are now rushing to inoculate kids in the affected areas with IPV from emergency stockpiles.