The federal government had declared it had beaten back the coronavirus in February.

Health experts said India became complacent in the winter, when new cases were running at about 10,000 a day and seemed to be under control. Authorities lifted restrictions, allowing for the resumption of big gatherings.

Others said that it could also be a more dangerous variant of the virus coursing through India. It is the world’s second most populous country and people live in close proximity, often six to a room.

“While complacency in adhering to masks and physical distancing might have played a role, it seems increasingly likely that this second wave has been fuelled by a much more virulent strain,” wrote Vikram Patel, Professor of Global Health at Harvard Medical School, in the Indian Express.

Experts say the only way India can turn the tide is to ramp up vaccinations and impose strict lockdowns in the so-called red zones of high infection. It has opened up the immunisation programme to all adults but faces a shortage.

India is currently using the AstraZeneca shot and homegrown Covaxin. It has also approved Russia’s Sputnik V and has urged Pfizer Moderna and Johnson and Johnson to provide it with vaccines.