Raising eyebrows at the Russian healthcare regulator’s swift approval to the vaccine that was still under trial, experts in Kolkata said that while it had whipped up a lot of excitement among people desperate for a shot that will insulate them from the virus, they warned that cutting trials short could raise doubts over its efficacy in the absence of robust data and its interpretation and raises serious ethical issues.
“A vaccine has to go thorough series of trials on aspects like safety, immunogenicity (immune response) and kind of antibody the vaccine produces. They need to be studied and analyzed in great detail before the vaccine is approved for mass production,” said Dipika Sur, a former scientist at ICMR-NICED who has been involved during clinical trials of vaccines like that of cholera and typhoid.
While pre-clinical trials are conducted on animals, clinical trials in humans go through three phases. In phase 1, the vaccine is administered on a small number of volunteers (20-80) to see if it is safe. In the second phase, it is administered to a larger group of volunteers (200-500) to study the safety as well as immunogenicity and antibody production. Phase 3 is carried out on thousands of volunteers to find if the antibody is protective and also how long the immunity lasts.
“We need to know how long the vaccine will protect the person against Covid-19. We also need to know the side-effects of the vaccine along with its efficacy,” said Subhrojyoti Bhowmick, director of clinical research at Peerless Hospital.
While Phase 1 and Phase 2 trials can be completed in two-three months, the third phase takes longer. Even if researchers are racing against time, it will take at least six months to find out how well the antibody works. “We do not have any data to comment on it. There is no data released in scientific journals other than claims by their own news portals. If it is true and found effective, then it will be an unprecedented human feat,” said Dipyaman Ganguly, associate professor at the translational research unit of excellence of Indian Institute of Chemical Biology
Health experts said a healthy individual can get vaccine-induced diseases and hence the adverse data profiling is an equally important part of trials. For example, if the vaccine is potent, it will protect against Covid-19 but the vaccine could induce another ailment — heart attack, stroke or anaphylactic shock — in case the side-effects were not properly studied.
“Russian president Vladimir Putin has himself declared that the clinical trial is still incomplete. So there can’t be any assurance yet of a higher level of safety, effectiveness and absence of long-term side-effects. All safety issues cant be monitored so quickly,” said infectious diseases control specialist Debkishore Gupta of CMRI.