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.