The government expects a covid-19 vaccine to be ready for sale as early as December if clinical trials are successful, a senior health ministry official said.“It is difficult to say when the vaccines will be available. It depends on how the trials go and when the vaccines get regulatory approval. But the earliest it is expected in late December or January,” the official said on the condition of anonymity.The Serum Institute of India has advanced the furthest in clinical trials in India, currently conducting phase 3 trials of Covidshield, which has been jointly developed by the UK’s AstraZeneca and the University of Oxford.Other vaccines being developed by Bharat Biotech International Ltd and Zydus Cadila are expected to follow soon in early 2021, subject to the successful completion of all three phases of human trials and Drug Controller General of India V.G. Somani’s approval. Both are currently in phase 2 trials.Experts said the government’s expectations are unrealistic.Vineeta Bal, professor of biology at Indian the Institute of Science Education and Research in Pune, said she does not expect any of the vaccines to be ready by December.“I don’t expect any of the vaccines to be good enough for regulatory approval and commercial launch as none of them will have robust data of long-term efficacy for a large number of participants. The trials will have just about four months or less of efficacy data,” Bal said.While AstraZeneca is conducting human trials with up to 50,000 participants in total in the UK, US, Brazil, Japan and South Africa, Serum Institute is conducting the trial in India with 1,600 patients.Early results from both companies’ trials are expected by December. However, AstraZeneca’s trials in the US have been on hold since early September after an unexplained illness occurred in the UK phase 3 trial. UK, India and other countries resumed trials after regulators reviewed data.Zydus Cadila and Bharat Biotech are on the verge of completing their phase 2 trials, with Bharat Biotech applying for DCGI approval to start the last stage.Spokespeople for Serum Institute of India, Bharat Biotech and Zydus Cadila declined to comment.Another firm that could potentially be ready with vaccines is Dr Reddy’s Laboratories Ltd, which has a pact to distribute Russia’s Sputnik V vaccine. Under the pact with Russian Direct Investment Fund, Dr Reddy’s will conduct clinical trials of the vaccine and distribute up to 100 million doses after it receives approval.Even if the first batches of vaccines become available as early as in two or three months, they will not be given to young and healthy people in India first—the government, as well as the World Health Organization, have prioritized frontline healthcare workers first, followed by the elderly and people with co-morbidities, who have the highest risk.