Covid. BL Explainer: Does the booster dose work against Covid-19?

What is a booster dose?

A booster dose is given to those already vaccinated to help shore-up their immunity levels after a period of time. So babies, for instance, are given their childhood vaccines and booster doses for life-long protection against polio, measles and so on. But the world is presently gripped in a dilemma over booster doses for the Covid-19 vaccine, as studies show declining antibody protection within about six months of the mRNA vaccines, for instance. And a booster dose could then help restore the vaccine’s effectiveness in creating antibodies in an individual who shows declining immunity against the virus.

Is there conclusive research on the need for it?

Research calls for a nuanced approach. Public health experts say a third dose may be necessary as part of the primary vaccination in vulnerable populations who may not have adequate antibody protection despite the first two doses. Vaccines are known to be less efficient in the elderly, for example, in creating an adequate antibody protection against the virus. People who are immunocompromised because of their treatment for cancer, or those who may have had an organ transplant and so on are defined as vulnerable.

Is it allowed in India?

There is no decision yet, but there is a clamour for the same from several public health voices – especially for frontline workers, essential workers etc who would got their vaccines in January/ February this year, and may be witnessing waning immunity. The declining protection could endanger the lives of the frontline staff as they continue to remain engaged in Covid-19-linked duty.

And, India is reported to have stocks that may be running close to its expiry date. So this cannot be exported. Instead of running the risk of it being wasted, public health voices are suggesting they be used as boosters for frontline staff and high-risk populations.

Have other countries allowed it?

Yes, countries like Israel have gone right ahead with their boosters campaign. And the United States and Europe are on the verge of the same. This comes as studies show declining immunity/protection from vaccines six months on. And add to this the highly-transmissible Delta variants and a large number of unvaccinated population as well. Europe for instance is seeing a surge of cases in countries like Germany that have a reasonably vaccinated population, and this is being seen by some as grounds for a booster dose. Just months ago, though, the US Food and Drug Administration’s advisory panel had advised boosters only for high-risk populations.

Should the booster be the same as the original vaccine ?

Countries are going with a mix and match approach and companies are studying their vaccines in the role of a universal booster; case in point being the Russian vaccine’s single dose version — Sputnik Light. Studies are on to evaluate its efficacy as a booster after two shots of the AstraZeneca-OxfordUniversity vaccine. All types of combinations are being looked at in different countries and in India too, experts say, it would follow the same pattern of taking which ever vaccine is available as a booster.

What is WHO’s view on it?

The WHO is not for boosters and has called for a global moratorium till the year end. They have said a third dose as part of the primary vaccination can be given to vulnerable, at-risk populations. The WHO’s stance is based on two factors - studies that do not show the need for a booster in healthy populations and the lopsided distribution of vaccines across the world that has left several low income countries with no vaccines for their frontline workers. This raises a moral question on governments cornering vaccine supplies even as it leaves the world open to the risk for infection-spread. As the WHO repeatedly points out, no one is safe, until everyone is safe.

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