New Delhi: Haryana Health Minister Anil Vij tested positive for Covid-19 on 5 December, just over two weeks after he was administered a trial vaccine shot of Bharat Biotech’s Covaxin. Following this development, the vaccine is under a tight watch.
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.Ads code goes here
— ANIL VIJ MINISTER HARYANA (@anilvijminister) December 5, 2020
While there is speculation that Vij may have tested positive because he was administered a placebo, domain experts say there is a need to keep faith in the vaccine regardless and not be deterred by this incident.
The experts told ThePrint about how the vaccine works, and why one case should be not taken as a benchmark for a vaccine that is still under trial.
The Haryana minister was administered the first of the two-part dosage of Covaxin in Civil Hospital, Ambala Cantt on 20 November. He had then issued a statement saying he is fit and fine.
— ANIL VIJ MINISTER HARYANA (@anilvijminister) November 20, 2020
After he tested positive last week, Bharat Biotech released a statement highlighting details about the trial, but didn’t mention Vij.
“COVAXIN clinical trials are based on a 2 dose schedule, given 28 days apart. The vaccine efficacy will be determined 14 days post the 2nd dose. COVAXIN has been designed to be efficacious when subjects receive both doses and post the 14 day period after the 2nd dose. The phase 3 trials are double blinded and randomized, where 50% of subjects will receive vaccines and 50% of subjects will receive placebo.”
Covaxin is being developed by Bharat Biotech in collaboration with the Pune-based National Institute of Virology.
What the experts say
According to Dr Gagandeep Kang, India’s leading vaccine expert and a professor at Christian Medical College, Vellore, Vij’s infection is unfortunate but it doesn’t mean the vaccine is not working.
“It is important to understand that he was in a trial, so he may have got a vaccine or a placebo. Even if he did get the vaccine, he received his first dose two weeks before his infection was diagnosed. By the time an infection is diagnosed, a person is usually already infected for a few days, so he may have been infected a week or so after taking the vaccine and before he had an immune response to protect him,” she said.
“It takes a minimum of two weeks for antibodies to form, usually about three weeks. For a two-dose vaccination like Covaxin, we expect protection about two weeks after the second dose and Mr Vij had not only not got his second dose, he was 14 days after the first dose at which time it is unlikely that any vaccinated person would be protected,” she said.
She added that Vij being a “notable personality, gives scientists an opportunity to explain better how and when vaccines work, so that everyone understands that having got a vaccine does not mean that we are immediately protected from infection”.
Dr Raman R. Gangakhedkar, former head of epidemiology and infectious diseases at the Indian Council of Medical Research (ICMR), spoke about the process of a vaccine trial.
“It is important to understand that whenever a vaccine is administered there will be two groups, one which is given the vaccine and the other which will receive a placebo. Placebo is a lookalike agent of the vaccine but has no immunising properties of the vaccine,” he said.
“A double blind study, such as this one, is when the participant and the doctor do not know which dose is which,” Gangakhedkar said.
In the case of Vij, it is important that “people who take the vaccine adhere to Covid appropriate behaviour for at least two months”.
“Here in Vij’s case, not only do we not know what his dose consisted of, we also need to remember that he was given half the vaccine. It would not be safe to assume that half the dose of a two-dose vaccine would provide claimed/expected immunity against Covid-19,” he added.
He also explained the nature of the Covid vaccine that was administered to the minister.
“The Covid vaccine made right now uses the prime-boost immunisation strategy. What it does is the body is first primed with one antibody or immunogen and then a second dose which boosts the body’s immune system and may act like a reminder to the body to recall that you are committed to produce immune response against the organism,” he said.
‘Story of one individual’
K. Srinath Reddy, president of the Public Health Foundation of India (PHFI), gave an insight into the make of the vaccine.
“There are two factors at play here. First, we need to understand that most of the vaccines we are seeing right now are intramuscular vaccines. The intramuscularly administered vaccines are not sterilising vaccines which can prevent infection in the first place. The virus can still infect the nose or throat. These vaccines will then fight the virus and overcome it to prevent serious disease,” he said.
“Mucosal vaccines or sterilising vaccines are those which can be inhaled. They produce IgA antibodies or secretory antibodies. They can prevent the infection,” he said.
“Such vaccines are still in early stages of evaluation in Covid-19. So, we must differentiate between disease preventing vaccines and infection preventing vaccines. Otherwise, we will set wrong expectations,” he added.
Reddy said the second important factor “is that Anil Vij was administered only the first of the two vaccines, hence the immunisation may not have had a complete effect”.
Dr Satyajit Rath, an immunologist at the Indian Institute of Science Education and Research, Pune, quashed the need for knowing whether Vij was administered a placebo.
“This is a story of one individual, vaccine trials are done on thousands of people. We should wait for numbers to accumulate. What happened to an individual is not the outcome of the trial,” said Rath.
“Vij is a part of a double blind trial, therefore we have no reason to know or demand the knowledge of whether he was given a placebo or the vaccine. Let the researchers publish the findings of the study. Additionally, he acquired the infection before he was administered the two doses of the regime, this tells us nothing about anything,” he added.