Extending intervals between vaccine doses could leave people vulnerable to infection by one of the Covid variants in circulation, Dr Anthony Fauci, the medical advisor to the United States President, told NDTV Friday.
Dr Fauci was responding to a question about recommended intervals in the light of revised guidelines by the Indian government last month.
"The ideal interval between doses for mRNA vaccines is three weeks for the Pfizer and four for the Moderna. The problem with extending intervals is that you become vulnerable to variants," he said.
"... and we've seen that in the UK, where they extended that interval, in that period you can get infected by the variants. So we recommend staying on schedule," Dr Fauci explained.
However, he also said it may be necessary "if you have a very small supply".
Last month the government extended the gap between doses of the AstraZeneca vaccine (manufactured and sold in India as Covishield) to 12-16 weeks - from the existing six-eight weeks.
That was the second time in three months Covishield dosage intervals were widened; in March states and UTs were told to increase the gap from 28 days to six-eight weeks "for better results".
Widening of Covishield dosage intervals have been linked to increased efficacy.
However, the changes came amid an acute shortage and sparked suggestions the government was trying to eke out stocks to give as many people at least one dose till supplies are replenished.
India, last month, extended the recommended dosage interval for Covishield to 12-16 weeks (File)
At the time Dr Fauci said it was a "reasonable approach".
Speaking to NDTV Friday, Dr Fauci also stressed that point - the need to vaccinate people as quickly as possible to stay ahead of the virus, particularly the more infectious 'delta' variant.
The 'delta' strain was first detected in India last year, and data suggests it is behind the second Covid wave in the country. Experts say it is between 40 and 50 per cent more infectious.
"The delta variant, that is dominant in many states in India, spreads much more readily and efficiently from person to person. So any country that has the Delta variant should be concerned that there will be a surge of infections, particularly, if that particular country does not have a substantial proportion of their people vaccinated. We've seen that when Delta variant spreads among non-vaccinated people it can become dominant very, very quickly. That's what is going on in the UK that the Delta variant is taking over. It is close to 90% dominant now," he said.
On Wednesday, studies by AIIMS and the NCDC - neither of which have been peer-reviewed as yet - suggested the 'delta' may be able to infect even people who have been fully vaccinated.
Nevertheless, vaccination remains "key to (successfully) battling COVID-19", Dr Fauci said, adding that it is important to get vaccinated even if you have already been infected by the virus once before.
India has administered around 24.6 crore vaccine doses so far, but, given the country's population, that translates into a little over three per cent of people having been inoculated.
Experts like Dr Fauci have warned that vaccinating people, quickly, will be key to protecting populations against a third or any future waves of infection.
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