Bharat Biotech’s Covaxin safe, says Phase 1 trial data
India’s first domestically produced vaccine against Covid-19, Covaxin, triggered robust immune response, and reported no major adverse events shows findings from the Phase 1 placebo-controlled, randomised, double-blind trial on the safety and immunogenicity published by Bharat Biotech in a pre-print study on Wednesday.
Only one serious adverse event was reported, which was found to be not vaccination related, according to the study.
The results of Phase 1 results of Covaxin had not been publicly released yet even though the data was first presented to Drugs Controller General of India (DCGI) on October 2 when the company applied for approval to start Phase 3 trials.
“BBV152 induced binding and neutralising antibody responses… Vaccine induced neutralising antibody titers were reported with two divergent SARS-CoV-2 strains. BBV152 is stored between 2°C and 8°C, which is compatible with all national immunisation programme cold chain requirements,” says the paper, which is yet to be peer-reviewed.
To be sure, data given in the study released on Wednesday only pertains to the first of the three-phased clinical trials for vaccine authorisation. In Phase 1, initial testing of the vaccine candidate is carried out in small numbers of healthy adults to primarily test its safety. The results of this phase do not play a role in the market authorisation.
Other organisations that have been developing Covid-19 vaccines published data from their Phase 1 trials several months ago. Moderna Inc, for instance, published its Phase 1 data in July. The Pfizer/Biontech vaccine, which has already started being administered in the United States and Britain, released data from their vaccine’s Phase 1 results in August.
Phase 2 involves larger numbers of subjects and is focussed on data about a vaccine’s ability to safely produce its desired effect (immunogenicity).
The Phase 3 is the pivotal study on which licensing is based and it checks for the effectiveness of immune reaction triggered by the vaccine. Efficacy of the vaccine will be determined only in Phase 3 trials. The results of Phase 3 are finally presented as the data on which authorisation is obtained. Bharat Biotech has not yet submitted results of Phase 3 trials, which began in mid-November. On December 7, the firm had applied to DCGI for emergency use authorisation for Covaxin, following which the Subject Expert Committee (SEC) recommended that it present the safety and efficacy data from Phase 3 trials in order for its application to be considered .
Bharat Biotech has developed the whole-virion inactivated SARS-CoV-2 vaccine candidate (BBV152) in collaboration with ICMR.
In the Phase 1 study, a total of 375 participants were randomised equally to receive three vaccine formulations (n=100 each); the control arm had 75 participants. Vaccines were administered on a two-dose intramuscular accelerated schedule on Day 0 (baseline) and Day 14. The primary outcomes were reactogenicity and safety. The secondary outcomes were immunogenicity. The follow-up visits were scheduled on days 7, 28, 42, 104, and 194.
Experts, however, say much depends on the Phase 3 trial results. “At this stage, there are many promising vaccine candidates but Phase 3 trial results will be significant in terms of which ones finally materialize,” said public health expert Professor K Srinath Reddy, who is also a member of the National Task Force on Covid-19 management.