Vaccine efficacy based on 2 doses: Bharat Biotech after Vij tests positive

After Haryana minister Anil Vij, who is a participant in the phase 3 clinical trial of Bharat Biotech's investigational Covid19 vaccine candidate, tested positive for the Sars-CoV-2 virus, the Hyderabad based vaccine maker clarified that Covaxin has been designed to be efficacious based on a two-dose schedule, given 28-days apart.

The company also clarified that the vaccine efficacy will be determined 14-days post the second dose. Further, Bharat Biotech International (BBIL) said that the phase 3 trials are double blinded and randomised where 50 per cent of the subjects will receive the vaccine, and 50 per cent would receive the placebo. BBIL also confirmed that the minister had not yet received two doses of the vaccine.

On Saturday, Vij tweeted, "I have been tested Corona positive. I am admitted in Civil Hospital Ambala Cantt. All those who have come in close contact to me are advised to get themselves tested for corona." According to reports, he participated in the trial on November 20.

At the moment, there is no way to determine whether the minister got the vaccine or the placebo shot.

Dr Shahid Jameel, senior virologist and director at Ashoka University explained that there were a couple of possibilities - one is that the minister is in a placebo group and since the trial is ongoing, the code cannot be broken to ascertain this. "Secondly, only one shot does not give sufficient immunity. He is not fully immunised as per protocol from phase 1 and phase 2 testing. Also, even after a full course of vaccination, some people can still get infected but the disease is mild," Dr Jameel said.

Covaxin is an indigenously developed Covid19 vaccine undergoing a trial on over 26,000 people across 25 sites in India to evaluate the efficacy of the vaccine candidate.

--- Company says 50% subjects receive placebo

--- Trial is on 26,000 subjects

--- Trial is double blinded and randomised

--- In an ongoing trial, one cannot break the code to know if minister received vaccine or placebo

--- Company says 14-days after two shots given 28-days apart, efficacy is to be determined

--- Experts even after full immunisation, people can get the disease, albeit a mider form