You must have heard it all by now - the Omicron variant of the novel Coronavirus is spreading like wildfire, your “fully vaccinated” status may not be enough to guarantee protection against it, and a wait for your booster dose is likely on the way. 

And just like that, there is a new buzzword in town - “booster”. Like a lot of pandemic terms, the concept of a booster dose may seem new to you, but it is not. 

Booster doses have been around for several decades, and are given for many other vaccines apart from COVID-19, such as Polio, Hepatitis B, and Tetanus vaccines. 

With Omicron, governments across the world aim to confer additional protection for the vaccinated yet vulnerable population by providing booster doses. Let’s find out the science behind booster doses. 

The Science Behind Vaccination

Vaccination helps your immune system develop protection against a disease by producing antibodies against the disease-causing agent. 

Vaccination also results in the production of cells of the immune system called “memory” T-cells and B-cells that will remember how to fight that disease-causing agent in the future.

Like other vaccines, COVID-19 vaccines are also not 100% effective. This may result in infection in a fully vaccinated person, which is referred to as a “vaccine breakthrough infection.”

Studies suggest that the effectiveness or protection provided by a vaccine reduces with time. Also, if a new strain starts spreading the same disease, as is the case with Omicron, the earlier vaccination may not be able to provide protection against the new strain. 

The Science Behind Booster Doses

Completing a course of vaccination (in India, that is two doses of a double-dose vaccine) may not be enough to grant continued protection against a disease. Thus, the booster dose, which is a third dose of the same vaccine you received earlier, boosts your immune system by re-exposing your body to the disease-causing antigen (a protein of the disease-causing agent). 

When you are re-exposed to a disease-causing agent through a booster dose, the memory response of your immune system is more vigorous and includes a heightened response by the antibodies and T cells. 

In this way, your body is expected to present a “boosted” immune response to the novel Coronavirus after receiving a booster dose. 

A booster dose is required the most for older people, immunocompromised individuals (with a weakened immune system), and those with chronic medical conditions, as their immune systems may not be able to provide efficient protection against a disease-causing agent.

In India, the administration of booster doses (also referred to as precaution doses) for frontline/healthcare workers and citizens above 60 with comorbidities (after consultation with their doctor) has begun in early January 2022.


1. Yale Medicine. 2022. COVID-19 Boosters: The Latest Advice. [online] Available at: <> [Accessed 17 January 2022].

2. Burckhardt, R., Dennehy, J., Poon, L., Saif, L. and Enquist, L., 2021. Are COVID-19 Vaccine Boosters Needed? The Science behind Boosters. Journal of Virology,.

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