Bharat Biotech's Covaxin, one of the two vaccines being administered as part of India's COVID-19 vaccine drive, is “well-tolerated, with no vaccine-related serious adverse events”, according to the results of phase 1 trial in 375 individuals published in the Lancet on Friday. The trial was a double-blind, multicentre, randomised, controlled one, and was conducted across 11 hospitals in India.
This trial to evaluate safety and immune response had been published as a pre-print in December, while the Lancet publication is a peer-reviewed one. The phase 1 trial was conducted on healthy adults between 18-55 years. “We report the interim findings from the phase 1 clinical trial of BBV152, a whole-virion inactivated SARS-CoV-2 vaccine. The vaccine was well tolerated in all dose groups with no vaccine-related serious adverse events,” the Lancet article reads.
The results indicate that the vaccine produced both “humoral and cell-mediated responses”, and the most common adverse event was “pain at the injection site, followed by headache, fatigue, and fever.” “The overall incidence of solicited local and systemic adverse events in this study was 14–21 per cent in all vaccine-treated groups, which is noticeably lower than the rates for other SARS-CoV-2 vaccine platform candidates, and similar to the rates for other inactivated SARS-CoV-2 vaccine candidates,” the article reads. BBV152 induced binding and neutralising antibody responses that were similar to those induced by other SARS-CoV-2 inactivated vaccine candidates, the results suggest. In Phase 1 trials that were conducted in July last year, the vaccination was given two weeks apart; in phase 2 trials (380 volunteers), it was given four weeks apart, which is the routine schedule in which the vaccination is being administered currently.
Phase 3 trials for Covaxin are ongoing—25,000 participants have been recruited, of which, 13,000 have been given both doses of the vaccination, according to Bharat Biotech. “This [Lancet] is the first clinical trial publication on a COVID-19 vaccine from India,” the company has said.
While phase 1 and 2 trials are done on smaller numbers, phase 3 trials are done on larger numbers of people to evaluate the efficacy of the vaccine. In the case of Bharat Biotech, even as results of phase 3 trials are awaited, the vaccine is being administered in an open label, “clinical trial mode”, where the vaccinees are to be followed up “actively” as opposed to “passive” follow-up, according to Rajesh Bhushan, Union health secretary. In the case of a passive follow-up, which would be the route taken in Serum Institute's Covishield, Bhushan said that the onus would be on the vaccinee to report any adverse event. In active case, however, each vaccinee would be followed up via phone calls by the vaccinators to check on their status, he said.