"It's been done to save vaccine doses," Narendra Kumar Arora, head of the government's National Technical Advisory Group on Immunisation, told Reuters on Friday. "We discussed delaying it by three months, six months or nine months, but finally we said 'we can manage it with three months, let's do three months for now'".
Arora said that given the vaccine shortage in India, the focus should have been on immunising the most at risk.
"Our group prioritised those aged 45 or more," he said. "Because 75 per cent of the mortality and morbidity is in that age group."
The Ministry of Health and Family Welfare said on April 19 that the decision to include all adults in the immunisation campaign was taken in a meeting chaired by Modi.