As the tide of the terrible second Covid-19 wave slowly recedes and India braces itself for a possible third wave, the biggest irony is the snail’s pace at which the vaccine programme is progressing owing to serious supply bottlenecks. This much was clear from the change abruptly imposed four months into the vaccination drive that extended the intervals between two jabs of Covishield, which accounts for the bulk of the vaccines administered, from six to eight weeks to 12 to 16 weeks. This is the second time the interval was tweaked; the first, early in the programme, was from 30