The central government has allowed Bharat Biotech to start a Phase-2 clinical trial of a third booster dose of its coronavirus vaccine Covaxin. A subject expert committee (SEC) of the Drugs Controller General of India (DCGI) has allowed the Hyderabad-based pharmaceutical firm to give the third dose of Covaxin to a few volunteers six months after the second dose.
Bharat Biotech had presented amendments in the approved Phase 2 clinical trial protocol for administration of booster dose after six months following the second dose.
Thereafter, the expert committee recommended the firm to conduct the booster dose study only in 6 mcg cohort. The expert panel also asked the firm to present the details of the primary and secondary objectives and various assessments to be carried out in the subjects.
Usually, Phase 2 trials analyse the immune response provided by the vaccine against a disease in a person, while Phase 3 tests for efficacy, or what proportion of people are protected by the vaccine.
Bharat Biotech had started its Phase 2 trial in August 2020, wherein it divided 380 participants into two groups, where one was given two doses of 3 mcg and another 6 mcg. In both groups, the two doses were given one month apart. While both dosage forms showed that the vaccine was safe and provided protection, the 6 mcg dose was selected because of a better immune response.
Bharat Biotech's Covaxin is among the two coronavirus vaccines that have been selected for mass vaccination drive by the Centre to contain the spread of COVID-19 in the country. Covaxin has demonstrated an interim vaccine efficacy of 81 per cent in Phase 3 clinical trials. The trials involved 25,800 subjects, the largest ever conducted in India, in partnership with the Indian Council of Medical Research (ICMR).