COVID 3rd wave could spread rapidly, but may see half of cases recorded in second surge: Govt panel scientist
A possible third wave of coronavirus may see half the daily cases recorded during the second surge and it can hit its peak between October-November if COVID-appropriate behaviour is not followed, said a scientist of a government panel tasked with modelling of COVID-19 cases.
Manindra Agarwal, who is working with the Sutra Model-- the mathematical projection of the COVID-19 trajectory, further said that COVID infection can spread faster during the third wave if any new virulent variant of SARS-CoV-2 emerges.
The panel, formed by the Department of Science and Technology last year to predict the surge of coronavirus cases using mathematical models, earlier came under sharp criticism for not anticipating the ferocity of the second wave of COVID-19 in the country.
M Vidyasagar, a scientist with IIT-Hyderabad, and Lt. Gen Madhuri Kanitkar, Deputy Chief (Medical) of Integrated Defence Staff, are other members of the panel.
Agarwal, who is a scientist with IIT-Kanpur, said factors like the loss of immunity, effects of vaccination and the possibility of a more virulent variant have been taken into consideration while predicting the possible third wave, which was not done while modelling the second wave.
"We have created three scenarios. One is optimistic, where we assume that life goes back to normal by August and there is no new mutant. Another is intermediate wherein we assume that vaccination is 20 per cent less effective in addition to optimistic scenario assumptions.
"The final one is pessimistic with assumptions different from the intermediate one: a new 25 per cent more infectious mutant spreads in August (it is not Delta plus, which is not more infectious than Delta variant)," Agarwal said in a series of tweets.
2 lakh COVID cases likley during possible 3rd wave
According to a graph shared by Agarwal, the second wave is likely to plateau by mid-August and a possible third wave could reach its peak between October and November.
In the pessimistic scenario, the third wave could see daily COVID-19 cases rise up between 1,50,000 and 2,00,000 in the country, the scientist said.
The predicted single-day count is less than half of what was recorded when the deadly second wave had hit its peak in the first half of May, claiming thousands of lives daily and leading to shortage of oxygen supply and beds in several hospitals.
On May 7, India had recorded 4,14,188 COVID-19 cases, the highest daily figure during the second wave.
3rd wave analysis delayed for 3 reasons
Explaining the reasons behind the delay in coming out with an analysis for the third wave, he said: "It took us a while to do the analysis for three reasons. First, loss of immunity in the recovered population. Second, vaccination induced immunity. Each of these two need to be estimated for the future.”
"And third, how to incorporate these two factors in the Sutra model. Fortunately, it turned out that both can be incorporated by suitably changing contact rate and reach parameters... The first two factors required detailed analysis," he tweeted.
Contact rate is how fast the infection spreads and reach parameter is the percentage of the population the pandemic is active in.
Agarwal further that his team examined the studies done in the past on loss of immunity while making the projections.
"Similarly, we also looked at the projected vaccination rate over the next few months, including the effects of vaccine-hesitancy, and arrived at month-wise estimates for vaccination," he said.