India has given the green light for the COVID vaccine developed for emergency use by AstraZeneca and the University of Oxford, Reuters and other news sources reported Sunday.

The approval clears the vaccine's distribution in the second-most populous nation in the world which, after the U.S., has the biggest number of COVID cases.

The decision came on the same day as a countrywide drill for vaccine delivery, in which medical frontliners were given placebos at each of the health facilities to be used across India, was conducted.

India wants to begin immunizing people soon, most likely by Wednesday, sources, who requested not to be named, said. A representative of India's Central Drugs Standard Control Organization declined to comment. CDSCO has called a media conference on Sunday.

The CDSCO is also evaluating emergency-use authorization applications by Pfizer and BioNTech, and by India's own Bharat Biotech. Argentina and Britain have already approved the AstraZeneca vaccine for emergency use.

In an interview with reporters on Saturday, Information and Broadcasting Minister Prakash Javadekar said, "Last year began with corona, but this year is beginning with a vaccine." The vaccine is awaiting a formal response from India's Drugs Controller General, which is expected soon.

Javadekar said at least two more vaccines were awaiting approval - Russia's Sputnik-V and Zydus Cadila's ZyCoV-D. One was approved Friday for emergency use, Serum Institute's Covishield, he said.

While clinical trials for Oxford-AstraZeneca raised doubts about its effectiveness, it is considered safe compared to Moderna and Pfizer-BioNTech vaccines. It is also more affordable and easier to distribute compared to other experimental vaccines.

India's vaccine regulator is likely to authorize administering two shots for AstraZeneca-Oxford vaccines, each four weeks apart, sources said. Calls to CDSCO were unanswered outside regular business hours.

India has reported over 10 million COVID infections, although the country's rate of transmission has eased significantly from a mid-September surge. India is optimistic it could vaccinate around 300 million of its 1.3 billion population in the first six months this year.

Health authorities say vaccinations will be free of charge to the 30 million healthcare workers who will receive the treatment in the first phase. Immunization is voluntary.

SII, the largest maker of vaccines globally, has already stockpiled around 50 million doses of the AstraZeneca-Oxford product, which will be sold to the government at around 250 rupees (£2.50) per dose and 1,000 rupees on the private market.