India will open its Covid vaccination drive for adolescents and start administering booster doses to its at-risk adult population, Prime Minister Narendra Modi announced on Saturday.
The highly-infectious Omicron variant has gained a foothold in the country, and the health ministry has raised concerns about its onward spread.
"After looking at global developments and examining the last 11 months of our Covid-19 vaccination drive, our scientists have taken key decisions today," he said in his national address.
It is time to be "careful and cautious", he added, announcing that vaccines will be available for children aged 15 and up from January 3.
The country's healthcare and frontline workers, people above 60 years and citizens with underlying conditions will also start receiving their "precaution dose" a week later, the premier added.
India's vaccination drive got off to a slow and glitchy start in January but picked up pace after the devastating second wave in May that thoroughly exposed the national health infrastructure.
New Delhi has since administered more than 1.41 billion, mostly domestically produced, Covid-19 vaccine doses.
The country's nearly 480,000 Covid deaths are the third-highest, behind the tolls in the United States and Brazil.
But under-reporting is widespread and some studies have estimated India's true toll could be up to ten times higher.