EJ explainer: India's precautionary shot, world's booster shot - is there a difference?

Late on Saturday night, Prime Minister Narendra Modi addressed the nation to announce vaccines for children aged 15-18 years and booster shots for citizens above age 60 with co-morbidities and health workers.

Vaccine drives for children to begin from January 3rd, he said while booster shots or 'precaution dose' as the PM termed them will start rolling out from January 10 onwards. While making the announcement, the prime minister used the term precaution dose and did not call it booster dose as it has been generally referred to.

But what is a 'precaution dose' and how is it different from a 'booster shot' that the rest of the world is talking about?

Top government sources told The Indian Express that there is preliminary consensus in the country’s top technical advisory body on Covid vaccination that the third dose of Covid-19 vaccines must be different from the primary unit used for the first two doses.

It is very likely that the precautionary dose will be a vaccine of a different platform, government sources were quoted as saying.

'So, the preliminary consensus is,' a source continued, 'that a beneficiary cannot take three doses of Covishield or Covaxin.'

What are alternatives for third doses then?

According to top virologist, Dr. Gagandeep Kang, the best booster shots available are that of mRNA vaccines.

She also added that while India could get Pfizer or Moderna vaccines which are mRNA based or wait for the indigenous mRNA vaccine being developed by Pune-based Gennova Biopharmaceuticals Ltd.

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Other likely alternatives can be vaccines being manufactured by Indian pharmaceuticals, Hyderabad based Biological E's Corbevax, Serum Institute of India's Covovax and Bharat Biotech's intranasal vaccines.

These vaccines are expected to be rolled out in 2022 for the general population.

While booster shots are being recommended by experts across the world, pharma company Cipla's CEO Umang Vohra is of the opinion that third doses will not be as beneficial in the long run.

'Covid-19 will soon become a common flu so what happens with the flu vaccines is that every year booster doses are created around a particular strain of the flu that was seen last,' Vohra explained.

In Covid, we have not been able to see that, he says. The booster is basically the prime dose. With time, we will see booster being engineered to a particular strain, be it Delta, Alpha or any other new strain and that will perhaps create a better booster cycle, the CEO elaborated.

The difference between precautionary doses and booster doses, simply put is that of the vaccine used to administer the third shot.

Boosters use the same platform used for the first two doses. While precautionary doses are expected to administer the shot using a new vaccine or a previously unused, existing vaccine.

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