Controversy around Bharat Biotech's Covaxin approval without efficacy data

On a day when Bharat Biotech's Covaxin, an indigenously developed Covid19 vaccine got a nod from the country's regulator, on the grounds that it may offer protection against the mutated strain of Sars-CoV-2 from the UK, experts did raise some doubts about the logic behind the approval. A controversy erupted around the approval with political leaders taking to social media to express their opinion. 

Bharat Biotech's Covaxin is based on a whole inactivated virus platform, an old technology which is used to make vaccines given to infants. Theoretically, such vaccines (based on a whole virus) can work against different variants of the virus. However, as the phase 3 efficacy trials are underway for Bharat Biotech, one does not have efficacy data on the vaccine yet. 

Of the 25,800 volunteer study initiated across the country, at least one shot has been given to 22,500 people. Once the full immunisation is done, one has to wait for a statistical number of disease cases in the sample when one can un-blind the data (who got a vaccine and who got a placebo). This would help in analysing the efficacy. Thus, it is still some time until the efficacy data is available for review. The Drug Controller General of India has given a nod to the vaccine which is under-trial saying that in 'public interest' as an 'abundant precaution' the permission for restricted emergency use has been granted in 'clinical trial mode' to have more options for vaccinations, 'especially in case of infection by mutant strains'. 

Raising a question mark on this, Gagandeep Kang, clinical scientist and professor at Christian Medical College, Vellore told a television channel that it is hypothetical to assume that vaccine would work against mutant strains. "I understand that the argument from the SEC was that this is like an insurance against the UK variant of the virus. I am completely unaware about any data that Covaxin has any efficacy against any strain of the Sars-CoV-2 virus, let alone special efficacy against the specific strain. This is hypothetical at best in the absence of knowing that any vaccine is efficacious against any Sars-CoV-2 strain. It would be a stretch to assume that it would work against the UK variant," she told the media outlet.

Meanwhile, Health Minister Harsh Vardhan in a series of tweets backed the approval given to Bharat Biotech’s Covaxin developed in collaboration with Indian council of medical research and national institute of virology saying that there were no seroconversions in those who were provided vaccines in Phase II as well as Phase I of COVAXIN clinical trials. 

“Our experience with inactivated vaccines not having serious adverse events was also observed in Phase II done among 380 study participants in BBV152 trial in 21280 Person days follow up. No serious adverse events seen," Vardhan said. 

He said only 7 per cent of participants who received 6 microgram dose had ‘mild symptoms.’ Vardhan also criticised opposition leaders including Congress leaders Shashi Tharoor and Jairam Ramesh, Akhilesh Yadav for questioning the vaccine. “Disgraceful for anyone to politicise such a critical issue...don't try to discredit well laid out science-backed protocols followed for approving #COVID19vaccines. Wake up & realise you are only discrediting yourselves,” the health minister said.

On the other hand, Congress leader Shashi Tharoor said, The Covaxin has not yet finished Phase 3 trials. Approval was premature and could be dangerous. Asking health minister to clarify, Tharoor said, "Its use should be avoided till full trials are over. India can start with the AstraZeneca vaccine in the meantime."

Bharat Biotech claimed that the evaluation of Covaxin has resulted in several 'unique product characteristics' including long term persistence of immune responses to multiple viral proteins as opposed to only the spike protein, and has also demonstrated broad spectrum neutralising capability with heterogeneous Sars-CoV-2 strains.  "It has also shown to generate memory T cell responses .... indicating longevity and a rapid antibody response to future infections. Its most critical characteristic is the demonstrated safety profile, which is significantly lower than several other vaccines with published data," Bharat Biotech further added. 

The company said that it has already submitted all data (generated so far) to the regulator. Some feel Covaxin is being kept as a back-up option for vaccination. 

Speaking to a television channel, Randeep Guleria, director of AIIMS, Delhi said that Covaxin can be kept as a 'back-up' in case one approved vaccine shows any decline in efficacy because of a variant strain, then one will have a whole virus inactivated vaccine as a back-up. Theoretically at least, a whole inactivated virus vaccine is expected to generate an immune response against variant strains.