Covaxin trials: The curious case of Anil Vij and his knowledge of receiving a Covid-19 vaccine shot

In a double-blind trial, a volunteer would not know whether he/she is receiving a vaccine or a placebo

Questions on the efficacy of India’s first home-made Covid-19 vaccine rose on social media on Saturday following a Covid-positive disclosure from senior Haryana minister Anil Vij, who claimed to have taken that vaccine.

But the bigger question is: How did the minister know that he was administered the vaccine in the first place?

Going by his own admission, the 67-year-old minister received the vaccine at a hospital at Ambala cantonment on November 20 after he became the first volunteer for the vaccine’s phase-3 clinical trial in Haryana.

This, according to the experts, is impossible as the standard protocol for double-blind randomised control trials are being followed under which neither the trial volunteer nor the shot-giver would know who is getting what. So, a volunteer would not know whether he/she is receiving a vaccine or a placebo.

Read: Haryana minister Anil Vij tests positive for Covid-19 weeks after Covaxin shot; Bharat Biotech responds

In clinical trials, double-blind randomised trials are the gold standard to get the most accurate and unbiased results.

In a statement, Bharat Biotech said, “The vaccine (named Covaxin) is a fully indigenous one with the largest phase-3 clinical trial being conducted in India on around 26,000 subjects at 25 sites. The phase-3 trials are double-blinded and randomised, where 50 per cent of subjects will receive vaccines and the remaining 50 per cent of subjects will receive a placebo.”

The clinical trials are based on a two-dose schedule, given 28 days apart, and the vaccine efficacy will be determined 14 days post the second dose.

Responding to the social media comments on the vaccine’s efficacy, a spokesperson from the Union Health Ministry said, “The antibodies against the infection build up in a human being only after a specific number of days post the second dose of the vaccine as this is a two-dose vaccine. The minister in question (Vij) has taken only one dose of the vaccine.”

Read more: Covaxin a 2-dose coronavirus vaccine, Anil Vij got only first dose, says Union Health Ministry

But the statement begets the same question: How did the Health Ministry know whether the minister received a vaccine and not a placebo? The spokesperson did not clarify despite repeated requests.

Reached out for comments, a senior researcher associated with the vaccine’s clinical trial in Haryana said, “Ask the minister, how he knows he got the vaccine and not a placebo?"

The phase-3 trial of Covaxin is the only efficacy trial being conducted in India for Covid-19 vaccines, to determine its suitability to the diverse Indian population. The vaccine had cleared the first two phases of the trial successfully.