Indian Council of Medical Research chief Balram Bhargava on Tuesday said Bharat Biotech’s Covid-19 vaccine has been cleared in the clinical trial mode, reported the Hindustan Times. The Drugs Controller General of India has faced criticism from scientists for the decision to grant emergency use authorisation to Bharat Biotech’s Covid-19 vaccine without phase-three trial data about its efficacy and safety.

“Permission for restricted use in clinical trial mode has been allowed, which means consent of participants has to be taken and there has to be a regular follow up of participants,” Bhargava said at a press conference.

Clinical trials are divided into three phases. Phase 1 of a clinical trial is usually small and is used to determine its safety profile. Phase 2, on the other hand, employs a bigger sample size, and looks at the immune responses triggered by the vaccine. However, a vaccine is deemed safe to be commercially available only after Phase 3 – a much larger efficacy trial involving thousands of participants. Covaxin’s third-phase trial is still underway.

On January 3, the Drug Controller General of India approved Bharat Biotech’s Covaxin and Serum Institute of India’s Covishield vaccines for restricted emergency use in the country. The Serum Institute is the local maker of Covishield, the vaccine developed by Oxford University and pharmaceuticals company AstraZeneca. Bharat Biotech has manufactured India’s first indigenous vaccine candidate Covaxin in collaboration with the Indian Council of Medical Research and the National Institute of Virology.

Covaxin has faced reservations from various sections, including the Congress, for getting approval before publishing data for the third phase human trials. On Sunday, following the approvals, All India Institute of Medical Sciences Director Dr Randeep Guleria had said that Serum’s Covishield will be used in the initial phase of the vaccination drive, and Covaxin would be used in emergency situations or as a backup. Despite receiving approvals, the two companies are yet to sign a formal deal with the government.

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Bhargava, however, defended the decision to grant approval to the two vaccines. “The existing pandemic situation, high mortality, available science and lack of definitive treatments were considered by the subject expert committee [SEC] on Covid-19 of CDSCO for granting accelerated approval to these vaccines, and that is in our legal provision,” he added.

He added that restricted use of vaccine during a pandemic is considered based on safety and immunogenicity data even as phase three clinical trials are underway. “The immunogenicity data generated through phase two clinical trial serves as a surrogate for efficacy,” said the ICMR chief. “The Clinical Trial Rule, 2019, provides for considering phase two results to guide approval. Now the SEC guides the DCGI in the process of decision making for restricted use under emergency situation. Now we have two vaccines.”

The Ministry of Health and Family Welfare on Tuesday said that it would be ready to roll out coronavirus vaccines within 10 days from the date of emergency-use authorisation, based on feedback from the dry run.