Booster dose of Covid-vaccine

Most of us got our second and last jab months ago. Experts say that the immunity offered by Covid-19 vaccines wanes with the passage of time. So, as the third wave is threatening to take the world into its grip again, nations are mulling administering a third dose to its vulnerable population.

And India, which on Tuesday logged 1.68 lakh new Covid-19 cases and 277 deaths, has started vaccinating its population which is above 60 years of age and have comorbidities.

The booster shot is no different from the earlier doses which we had. It elicits an immune response from our body leading to production of antibodies, which in turn help the body fight the virus.

Meanwhile, there is no consensus on whether the booster shot should be different from the earlier two jabs that one had. Citing several experts, DownToEarth magazine recently said in an article that there is no peer-reviewed study in India on the efficacy of mixing vaccines.

In July last year, The World Health Organization’s chief scientist had asked individuals against mixing and matching Covid-19 vaccines. He said that such decisions should be left to public health authorities.

On the other hand, pointing to a study in the UK, BBC had last year said that a mix-and-match approach “appears to give good protection against the pandemic virus”. Some other studies have suggested that mixing-and-matching offers an even better immune response than using the third dose of the same series.

 Back home, the Indian government is staying away from mix-and-match policy for the booster dose for now.

For those fully vaccinated with Covishield, protection against fresh infection is just 3%. Protection against serious disease caused by Omicron is 18%, and against death 29%. Now, with a booster dose, this will increase to 80% protection against serious disease, and 88% against death.

Medical experts have also suggested that the government should reduce the gap between two doses of vaccines from the present 84 days or 12-16 weeks.

This would ensure speedier full vaccination of the entire eligible adult population. The Centre has, though, said that the interval between the second and third doses will be nine months. 

The decision to keep the interval between the second and third doses at nine months has been based on the findings of five scientific studies carried out by the Indian Council of Medical Research (ICMR) and the Translational Health Science and Technology Institute (THSTI), Faridabad. 

The third shot will for sure offer some shield to the elderly and the frontline workers from this ongoing wave of pandemic, even if it is from the same series.

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