A government study in July estimated that more than two-thirds of Indians already had Covid-fighting antibodies, mainly through natural infection. That gave them substantial protection even with one dose, unless more infectious variants emerge.
Not achieving full vaccination by December "will not be of any major consequence as recent serosurveys show a high degree of protection," epidemiologist Dasgupta added.
About 75% of India's adult population have received at least one Covid-19 dose, while 31% are fully vaccinated, according to government data. Only people aged 18 and above can currently be vaccinated in India.
"At least one dose we should be able to give to most of the adults by the end of the year," N.K. Arora, who leads a government group on immunisations, told the NDTV news channel late on Thursday. "Within the next 4-6 weeks after that, second doses will also be given."