A good vaccine usually takes at least 18 months, before it could be rolled out for production after fast-tracking all the mandatory regulatory approvals, said N.K. Ganguly, former director-general of the Indian Council of Medical Research (ICMR).

It was reported that India's first indigenous Covid-19 vaccine Covaxin may be released on August 15 under a fast-track mechanism. According to the government's top medical research body, a dozen institutes have been selected for clinical trials of the indigenous COVID-19 vaccine (BBV152 COVID vaccine). Ganguly said the strain of the virus was given to Bharat Biotech International Limited (BBIL) in May end, and in July, human trials have been scheduled.

On the lengthy process involved in vaccine development, he said even after spending many months and infusing a lot of funds the uncertainty of its success may continue. "It may be difficult to say whether the vaccine is successful or not", he added.

The ICMR in a letter said, "It is envisaged to launch the vaccine for public health use latest by August 15, after completion of all clinical trials. BBIL is working expeditiously to meet the target. However, the final outcome will depend on the cooperation of all clinical trial sites involved in this project."

Before the vaccine is tested on humans, challenge studies are done on mice and monkey; then a toxicology report is prepared, to check if the developed vaccine produces harm to cells; and it takes at least three to four months to finalize this report, said Ganguly. After this phase, the vaccine is tested on two rodents and a large animal and after successful completion of this stage the vaccine is ready for human trials.

"In Phase 1, the age group profiling is done (wherein vaccine study is done on people in different age groups). In Phase 2, nearly 600 to 700 people are vaccinated, and if the vaccine performs successfully in this phase then it progresses into Phase 3, which is called the efficacy study (in this phase, thousands of people are enrolled). Even after fast-tracking regulatory approvals, it will take at least 18 months to develop a good vaccine", said Ganguly.