Extending the interval between Covid vaccine doses could leave people vulnerable to infection by one of the many variants of the virus currently in circulation, Dr Anthony Fauci, the medical advisor to the President of the United States, told NDTV Friday.
Top Covid expert Dr Fauci was responding to a question about recommended intervals between vaccine doses in the light of revised guidelines by the Indian government last month.
“The ideal interval between doses for the mRNA vaccines is three weeks for the Pfizer and four weeks for the Moderna. The problem with extending intervals is that in-between doses you become vulnerable to variants,” Dr Fauci told NDTV.
“… 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,” he explained.
Dr Fauci also said that “if you have a very small supply of vaccines” it may be necessary to extend the interval between doses.
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.
“Based on available real-life evidence, particularly from the UK… increase dosing interval between two doses of Covishield to 12-16 weeks,” the government said in its statement.
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.
At the time Dr Fauci said it was a “reasonable approach”.
“When you are in a very difficult situation, the way you are in India, you have to try and figure out ways to get as many people vaccinated as quickly as you can, so I believe it is a reasonable approach to do,” he told news agency ANI.
Speaking to NDTV today Dr Fauci 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 in October last year, and available data suggests it is behind the second Covid wave in the country. Experts say it is between 40 and 50 per cent more infectious than the ‘alpha’ strain first detected in the UK.
“The ‘delta’… spreads far more efficiently and hence any country (which) has that variant should be worried… must have extensive preparation and vaccination to deal with it,” he said.