Booster doses of the COVID-19 vaccine might become necessary sometime next year - depending on how long the first two doses protect against hospitalisation and death - Dr Randeep Guleria, chief of Delhi's All India Institute of Medical Sciences (AIIMS) told NDTV on Saturday.
The AIIMS chief also discussed vaccination of children and said he was confident vaccines for kids - something other countries, like the United States, has recommended - would be rolled out soon.
Dr Guleria told NDTV the final decision on boosters - which have been allowed by countries like the US, Israel, the UK, the EU and the UAE - would have to be based on time (length of protection from the coronavirus) rather than the presence of antibodies.
"We don't have a definite answer, yet, on a timeline for boosters. We can't decide to give booster shots based on antibodies... it has to be based on time - i.e., how long has it been since you got the second dose. Normally after a year we can start looking at booster shots," he said.
"But we need more data... in the UK we are seeing increased cases but not increased hospitalisation or deaths. UK started vaccination in December (a month before India) and if we're not seeing greater hospitalisation then that means doses given in December seem to be holding out... if we keep that in mind we are still in a safe zone. But if the virus mutates (this decreases immunity) then sooner or later boosters must happen," Dr Guleria explained.
"Don't think there is a clear-cut plan now... talks are going on. I would think sometime next year is when we will look at boosters. We will first focus on more vulnerable sections - those with comorbidities and the elderly because they are at greater risk of severe Covid," Dr Guleria said.
The possibility of boosters next year was also suggested by Serum Institute CEO Adar Poonawalla, who told NDTV this week "we can wait for a year or so before considering boosters".
On vaccines for kids, the Drug Controller has approved Zydus Cadila's ZyCov-D but hasn't yet cleared Bharat Biotech's Covaxin, which was passed by the subject expert committee 12 days ago.
Dr Guleria said he could not answer for the DCGI but noted: "Two vaccines have been approved for kids... that is Covaxin and ZyCov-D, which is waiting to enter the vaccination schedule. Covaxin has been cleared by the expert panel and I am sure the Drug Controller General will clear it very soon."
Last week Dr VK Paul, India's Covid Task Force chief, said the final call on vaccinating children would be taken based on availability of vaccines and potential eligibility.
Dr Guleria said vaccines should be on "high-risk groups within children... like those with comorbidities... because they have greater risk of contracting severe Covid infections".
"Healthy children usually have milder infections and can be vaccinated subsequently, he said.
Finally, with Diwali around the corner, Dr Guleria also re-emphasised, as medical experts have been doing since the pandemic started, the importance of following Covid-appropriate behaviour.
"We have always been saying 'be careful during festive seasons' because there are crowds at this time and, in crowds, people tend not to follow Covid-appropriate behaviour," he said.
This warning comes amid red flags in Bengal, where daily cases have shot up after Durga Puja.
"We need to do three things - push for and follow Covid-appropriate behaviour, get (fully) vaccinated) and identify potential hotspots that we can quickly lock down and contain the virus," he said.