A sanitation worker became the first Indian to receive a Covid vaccine as the country began the world's largest inoculation drive.
Prime Minister Narendra Modi launched the programme, which aims to vaccinate more than 1.3 billion people against Covid.
He paid tribute to front-line workers who will be the first to receive jabs.
India has recorded the second-highest number of Covid-19 infections in the world after the United States.
Millions of doses of two approved vaccines - Covishield and Covaxin - were shipped across the country in the days leading up to the start of the drive.
"We are launching the world's biggest vaccination drive and it shows the world our capability," Mr Modi, said, addressing the country on Saturday morning.
He added that India was well prepared to vaccinate its population with the help of an app, which would help the government track the drive and ensure that nobody was left out.
Mr Modi spoke at length about doctors, nurses and other front-line workers "who showed us the light" in "dark times".
"They stayed away from their families to serve humanity. And hundreds of them never went home. They gave their life to save others. And that is why the first jabs are being given to healthcare workers - this is our way of paying respect to them."