Last week, after long drawn heated debates, the US FDA decided to authorise COVID vaccine booster doses for all adults over the age of 18.

According to the health authority, they took this call to counter the rising COVID cases in the country, and also in light of concerns of COVID vaccine immunity waning over times.

The US isn't the only country to do so. In fact, it joins a long list of countries that started offering a third booster shot (to a certain subgroup at the very least) of the COVID-19 vaccine when hey started seeing a rise in COVID cases in spite of having a high vaccination coverage.

But the question of whether to boost or not to boost is not a cut and dried one.

In India, a strong voice among experts holds that it would be unnecessary and unwise to start offering booster shots when a considerable chunk of the population is yet to be fully vaccinated.

However, earlier this month, the Indian Medical Association also called for giving booster doses to health care workers who are at a higher risk of exposure—the first line of priority when it comes to vaccinating.

Although India's stand as yet is unfavourable to booster shots, it could change depending on the trajectory of COVID cases in the country, in the near future.

FIT spoke to Dr Shahid Jameel, renowned virologist and Fellow OCIS and Green Templeton College, University of Oxford about vaccine immunity waning, if it's a cause for concern, and what it means for the future of COVID-19 vaccines and booster shots.

Below are excerpts of my conversation with him.

Dr Jameel emphasise that the vaccines do not prevent infections, and that they weren't necessarily designed to do so either.

"Rather, it prevents what happens downstream of infections, which is disease," he reiterates.

Explaining this, Dr Jameel says, "there are two types of protections that any vaccine give. One is called antibody based protection, and the other is called T cell based protection."

"That's not always the case. Because, you're not measuring T Cells really," he adds.

Apart from age, and other underlying health conditions being factors in determining how strong of an immune response you elicit, and for how long, Dr Jameel once again draws a line of differentiation between infection and disease.

"As your antibodies go down, you become more prone to infections, but you don’t become more prone to disease...it doesn’t mean that the vaccine didn’t work," he adds.

Does this, then, mean that COVID vaccine booster shots could become like the flu shots, an annual affair?

"We don’t know the answer simply because longer term studies just haven’t been done," says Dr Jameel.

"If the strain keeps changing, then I guess we will need an annual, or maybe boosters every two years, but remember, viruses cannot change endlessly." he says. "There will come a time when further change is unfavourable for the virus. If that happens, then you will not need boosters."

But, Dr Jameel also emphasises on the need to focus on expanding the primary vaccination coverage as much as possible before thinking of offering boosters for some.

"Countries that are giving boosters have reached a point of saturation with their vaccines... for India I think the priority should be to get the two shots to the people who are eligible to get the two shots," he says.

But, he also underscores that "if there’s one group of people who should get the boosters, that’s the healthcare workers."