Serum Institute of India chief Adar Poonawalla, in an exclusive interview to NDTV, said a version of Covishield, tailor made for the new Covid variant Omicron can be considered if research indicates a need. Tests are on for Omicron and a call on the matter will be taken another two weeks, when more is known about the new virus, he added.

"Scientists at Oxford are also continuing their research, and based on their findings, we may come out with a new vaccine which would act as a booster in six months' time. Based on the research, we would know about the third and the fourth dose for us all," he told NDTV.

It is, however, not essential that a specific version of the vaccine will be required for Omicron, he said.

"The Lancet has reported that Covishield's efficacy is very high and significantly reduces chances of hospitalisation and possibility of death... It is not necessary that the efficacy of Covishield would drop with time, he said, referring to the new study published in the peer-reviewed journal.

If a booster is needed eventually, he said the company has enough doses and it will be available at the same price.

"We have hundreds of millions of stock in our campus. We have over 200 million doses reserved for states and Union Territories in India. So, if the government is to announce a booster dose, we are well stocked," he said.

For now, the focus should be on prioritising the vaccine for those who did not have a shot and the second dose for those who had one.

"The message for all - and a priority - is for everyone to get the two doses of the vaccine. That is the first step to stay protected. It is only after that that one can enhance that safety with boosters over the next year… The focus of the government must remain to get everyone double vaccinated," he said.

The government has already made it clear that there is no plan for a booster shot – as is happening in some nations -- in the immediate future.

Defending the decision, Dr NK Arora, the chief of the Centre's Covid panel, contended that the situation in India and nations in Europe and North America are not similar.

A very large proportion of our population had contracted Covid and the vaccines are providing additional protection, he said.

Evidence of the extent of immunity prevalent in India became clear when ''the number of cases declined despite festivals'' and when large gatherings frequently broke Covid discipline across the country "during Diwali and Dussehra".

That said, a plan is being drawn up to provide additional shots to people who are immunocompromised, he added.