Despite vaccine, don’t lower guard: Experts
Experts welcomed Friday’s steps by a key government panel to approve a coronavirus vaccine but said the development must not be seen as a chance for people to begin letting their guard down in preventing Covid-19 infections soon.
Their comments came after the Subject Expert Committee of the Central Drugs and Standards Control Organization (CDSCO) cleared the Oxford-AstraZeneca vaccine, which will now need to be assessed for a formal approval by the Drugs Controller General of India.
“It is fantastic news that we have a vaccine in such a short time, however it will be counter-productive if people believe that now is the time to throw the precautions out of the window. First, the vaccine will be given to a very small number of people at the moment. There aren’t enough doses to immunise everyone in the world right now. Second, even for those who do receive the vaccine, the two doses would be at least one month apart and it will take about two weeks after that for the immune response to kick in,” said Dr Rakesh Mishra, director, Centre for Cellular and Molecular Biology. Some of the restrictions and the Covid appropriate behaviours will have to remain in place for at least six to eight months he said.
He added, “Third, the vaccine is 80 to 90% effective, meaning there would still be 10 to 20% people susceptible among the group that receives the vaccine. So, to protect everyone from the disease people will still need to follow the social vaccines of wearing a mask, maintaining social distance, and washing hands frequently.”
Maintaining the restrictions even when the vaccine become available is essential also because even those who do get the vaccine can still keep transmitting it to others who are susceptible.
Dr Shahid Jameel, director of Trivedi School of Biosciences at Ashoka University and former CEO of Wellcome Trust/DBT India Alliance said, “This is possibly the best news in a while. The good thing is that we are manufacturing it and we do not need to go begging for the doses. However, people will still have to take precautions because the vaccines have shown to protect from the disease and not infection. What this means is a vaccinated person can continue transmitting the infection to a susceptible population.”
Along with the vaccine roll-out in India and other countries, Dr Jameel emphasised on the need for stepping up genomic surveillance to detect mutations that can escape the vaccine.
When a large proportion of the population gets vaccinated, it results in the virus selectively mutating to evade the immune response generated by vaccines. This is just like over-use or incomplete use of antibiotics results in resistant strains of the bacteria. In vaccine, it usually happens in people who do not generate a robust immune response after immunisation, said Dr Jameel.
“If a virus does mutate under pressure from a vaccine, two things can happen. One, it might mutate in such a way that it is unable to infect human cells as effectively making it weaker. Or, it can still infect people effectively and dodge the antibodies, but the T cell response will still work against it, meaning it will result in milder disease,” said Jameel.