India has opened up COVID-19 vaccine booster dose for its 60-plus population while discussion continues on the merits of providing precaution dose to the general population of those over 18 years. Though the government is yet to make any announcement on the issue, experts and doctors are divided on how many booster doses are needed to minimise the negative outcome of the infection.
Booster doses are given with two objectives — to reduce the chance of getting infection and to reduce the chance of death, in the event of an infection. These two parameters must be seen separately, said Rajeev Jayadevan, vice-chairman, Research Cell, Indian Medical Association, Kerala.
He explained that the first depended on neutralising antibody levels which rapidly declined, while the second depended on T cells and memory B cells, which were long-lasting. “Two years into the pandemic, we are now learning that the umbrella of protection against infection depends on how long ago the most recent infection or vaccine dose was. Thus, whether they get infected or not does not depend only on the vaccine: exposure also plays a role,’’ he said.
