COVISHIELD is about 72% effective, based on late-stage trials done abroad.
India said on Tuesday it had no concerns over the efficacy of the AstraZeneca COVID-19 vaccine despite South Africa putting it on hold, and ordered 10 million more doses of the shot for its own huge immunisation campaign.
South Africa delayed use of the vaccine after researchers found it offered minimal protection against mild-to-moderate COVID-19 disease caused by the country's dominant coronavirus variant.
India, with the highest number of infections after the United States, has yet to detect the South African variant and will continue to use the vaccine in an inoculation drive that has covered 6.3 million front-line workers since January 16.
"Our vaccination programme is robust and valid, and I assure you that we are going ahead with it, not worried at the moment," Vinod Kumar Paul, a top vaccine official in the country, told a news conference.
"We will intensify our surveillance and we will be watching other developments in due course."
The Serum Institute of India (SII), the world's biggest vaccine maker, has licenced the vaccine from AstraZeneca and Oxford University and markets it as COVISHIELD for low-and middle-income countries.
India has ordered 10 million more doses of COVISHIELD on top of 11 million supplied earlier, an SII spokesman told Reuters on Tuesday. SII has agreed to sell at least 100 million doses to the government at a discounted price of Rupees 200 each, though the government says firm orders will be staggered based on its needs, and also on vaccine shelf-life.
Covishield is about 72% effective, based on late-stage trials done abroad, says the country's drug regulator.
The country is also using the COVAXIN shot developed at home by Bharat Biotech with Indian Council of Medical Research. Bharat Biotech has supplied 5.5 million doses to the government and is selling 4.5 million more, a company spokeswoman told Reuters.
The government wants to cover 300 million people by August, reaching the elderly and those with existing conditions by March.
India has reported 10.85 million infections and more than 1,55,000 deaths - though cases have fallen sharply since September.
MAKE IN INDIA
Mr Paul said Johnson & Johnson could manufacture its shot in India. He also said many more vaccines, including Russia's Sputnik V, Cadila Healthcare's ZyCov-D and a Novavax product, were in the queue.
"India is fortunate to have two great made-in-India vaccines, and as many as six-seven vaccines in the pipeline and perhaps many more," he said, days after Pfizer Inc pulled an application seeking emergency-use authorisation in the country.
The U.S. company had declined to immediately do a small local safety study for its shot and produce it in India, unlike the other vaccine developers.
New Delhi, meanwhile, is aggressively pushing the SII and Bharat Biotech vaccines abroad as part of a diplomatic campaign to recoup ground lost to China.
Bharat Biotech told Reuters it could export its vaccine to Brazil and the United Arab Emirates this week, a major success for the shot approved at home for emergency use without efficacy data from a late-stage trial.
The company expects results from an ongoing trial involving 25,800 participants in India only by March, though the country's drug regulator has called the vaccine safe and effective amid criticism from doctors and health experts.
A study on 26 participants has found COVAXIN effective against the UK strain of the coronavirus.
Bharat Biotech has also applied to conduct a Phase III trial for COVAXIN in Brazil, which plans to import 8 million doses in February and another 12 million in March.
Bharat Biotech has also sought emergency use authorisation in the Philippines.