Herd immunity may take away COVID-19 vaccine utility: AIIMS Director

New Delhi, Nov 13: AIIMS Director Randeep Guleria said on Thursday, if there's "herd immunity" against COVID-19 in India, and if the virus doesn't mutate or cause changes over time, a vaccine's utility will not be there.

"We're learning how the virus behaves over the next few months and based on that a decision on how frequently the vaccine is needed will be made," Guleria added while speaking an interview to IANS.

Here are the excerpts from the interview:

Q: If a vaccine is available off the shelf by beginning of 2022 or end of 2021 for common people, wouldn't they have attained immunity against this viral infection, or maybe Covid-19 scenario improved by then. People may treat this viral infection like common cold and cough, which does not have an adverse health impact?

A: There are two issues: One is immediate availability of vaccine to decrease and prevent the pandemic. So if a vaccine is available, if you are able to give it to the high risk group and those who have a higher chance of the infection as a priority, we would be immediately able to decrease the number of cases and also decrease the number of deaths.

But, we may reach a stage down the line where we may have a good amount of immunity and the people feel there is now good immunity, the utility of the vaccine is not there. And, if the virus doesn't mutate or does not cause changes that may need you to again vaccinate yourself, because you may get re-infection, then there will be less utilization of the vaccine down the line.

Q: You have mentioned about people having long-term side effects post their recovery from Covid-19 disease? If Covid-19 is from the coronavirus family, then why do patients develop medical complications that may have lasting health effects or prolonged illness?

A: Most of the previous viral infection we had, has been due to other viruses like influenza. Coronavirus, we have almost seven other viruses in subsets in this coronavirus family. Four of them just cause flu-like symptoms, which are very mild. The other three we have, one was SARS, which was controlled and did not lead into a pandemic. We also have MERS coronavirus, which is not that infectious, so we have small outbreaks.

Q: There is data to show that BCG protects against viral infections. Can a booster dose boost the immune system and protect people against Covid-19?

A: There is controversial data as far as BCG is concerned. There is in-vitro data from labs, which suggests BCG vaccination does give some degree of immune response, which has an anti-viral effect also. One retrospective study from Israel did not show any benefit to people who had the BCG vaccine. But there is another study from Netherland, which looked at people who are given the BCG vaccine five years ago for some other trial, and they found they had some degree of protection, as far as Covid-19 was concerned.