So what went wrong? On advice from global experts in 1978, the Indian government chose to use OPV as the preferred weapon to tackle polio, choosing it over the more effective but relatively more expensive injectible polio vaccine (IPV). As early as the 1980s, top Indian vaccine experts like T. Jacob John of the Christian Medical College, Vellore, had raised the red flag against the use of OPV. Although it is much easier to administer, OPV has a serious flaw. It is manufactured using a form of the live polio virus whose potency to cause polio has been blunted, but there are still cases in which the virus regains its potency and starts paralysing children. Strangely in India, such cases are not counted: they are merely categorised as adverse reaction to the vaccine. Writing an anguished editorial in the highly regarded Current Science journal recently, John said that “for three decades, policymakers ignored Indian science on polio—allowing over three million children to be paralysed unnecessarily and delaying polio elimination by 11 years”. The problem arose as decisions were made on the basis of opinion fit for western nations, says John, suggesting that the government made “bad mistakes”—for Indian research studies in the ’70s had established “why western tactics would fail”. Occasionally, the attenuated virus from the vaccine can also regain its infectivity and cause polio outbreaks later.