India's COVID-19 immunisation campaign has struggled to keep pace with demand, especially after a dramatic second wave of infections has left hospitals inundated with patients and killed more than 180,000 people since April.
Prime Minister Narendra Modi said on Monday the federal government would offer free COVID-19 shots to all adults, having faced criticism from health experts and the country's highest court for his inconsistent vaccine polices.
HOW IS INDIA'S VACCINATION PROGRAMME DOING?
The world's second most populous country has administered more than 231 million vaccinations since starting the campaign in the middle of January. That is only behind China and the United States.
Still, India has given at least one dose to just 14% of its 1.35 billion citizens, a much lower proportion than in countries such as Britain, the United States and Brazil. India has given the required two doses to less than 5% of its estimated 950 million adults.
It is currently using domestically made doses of the AstraZeneca PLC vaccine and Indian company Bharat Biotech's Covaxin.
WHY INDIA TURNED FROM VACCINE EXPORTER TO IMPORTER?
India - the world's biggest producer of vaccines for polio, diphtheria and other diseases - sold or donated more than 66 million COVID-19 vaccine shots to 95 countries until the middle of April.
But as infections started rising from around mid-March in India, the clamour for vaccines at home also increased. India then started looking for foreign vaccines made by companies such as Pfizer Inc/BioNTech SE, Moderna Inc and Johnson and Johnson.
None of the U.S. companies has formally applied to sell to India, though Pfizer is in active talks with the government. Millions of doses of Russia's Sputnik V have arrived in the country and its commercial sale is expected to start from next week.
The United States has also pledged to donate some AstraZeneca doses to India.
WHAT HAVE BEEN THE POLICY REVERSALS?
* India initially planned to vaccinate only 300 million of its health/front-line workers and the most vulnerable in the first six to eight months of the year. But Modi expanded the programme to all adults from May 1, though supplies were not meant to rise until June, leading to widespread shortages across the country.
* Modi's government asked individual states to buy vaccines from domestic manufacturers or import the shots themselves to inoculate their adults aged below 45 from May 1 onwards. Many states floated global tenders to import vaccines but none could secure doses via that route. Delhi's chief minister complained Indian states were made to compete against each other internationally for a scarce commodity.
Modi reversed the policy on Monday, saying the federal government would offer vaccines to all adults free of charge starting June 21. Rates for private hospitals - catering to those willing to pay for their shots - will be capped.
Modi said in a televised address all vaccine decisions have been taken based on consultations with state leaders.
* Modi's government placed no advance orders for vaccines from companies such as the Serum Institute of India (SII), the maker of the AstraZeneca shot, before it was approved in early January. It signed a purchase deal with SII nearly two weeks after the company's licensed version of the vaccine was authorised for emergency use.
Last week, the government placed its first advance order for a vaccine still undergoing Phase 3 trials, as it tries to speed up the immunisation drive.
* Until the second wave hit India ferociously, health officials had repeatedly said there was no need to vaccinate all adults. But in the past few weeks, the government has said all adults would be immunised for COVID-19 by December.