More than 100 million Indians have not turned up for their second coronavirus vaccine dose, official data showed, raising concerns of a resurgence in the disease despite a relatively low infection rate.Apart from leaving these people at risk of catching Covid-19, their “vaccine truancy” endangers India’s target of inoculating all adults by 31 December, a target that is in any case unlikely to be met owing to the earlier shortage of vaccines at the start of the inoculation campaign.“We have seen this complacency with tuberculosis patients. They start taking the drugs and after a few weeks, they feel better so they stop even though they have to take them for six months,” said Bhavna Dewan, a health worker in Nainital. “It’s a similar mentality with the vaccine. I’m sure they feel one dose is enough because no one is falling ill.”Mansukh Mandaviya, India’s health minister, is urging states to address the issue. From next month, he said, health workers will make door-to-door visits to find the truants.The figure of 103.4m missed doses comes just a week after India celebrated administering 1bn doses thanks to the efforts of health workers who trekked over mountains, picked their way through landslide rubble, crossed turbulent rivers, and braved jungles to reach the remotest hamlets.India has administered first doses to 725 million people, or to 77% of its’ 944 million adults, and second doses to 316 million, or 34%.But some experts are wondering if giving the second dose might prove to be even more of a challenge if complacency, spawned by the belief that the worst is over, has set in.For the last 29 days, new daily cases have been below 30,000. In the past few days, they have hovered around 13-to-15,000 a day, the lowest for eight months.Life has returned to something very close to normal. People are celebrating festivals with abandon, socialising, shopping, and eating out. The low daily new infection rate has made many Indians believe a third wave is unlikely. Experts have also been saying that, barring a new variant, a third wave seems a remote prospect.Still, Dr Satyajit Rath, a scientist at the National Institute of Immunology, said the 103.4 million figure was only a cause for concern if people never get their second shot.“If people have always dallied a little in coming in for their second dose, maybe coming a week or two or a month later than prescribed because they were busy, then it is not alarming. It simply means that many of these 103.4 million people will catch up. But if a larger percentage of people are coming in late, then it is concerning. But we don’t know,” he said.