An IIT-Kanpur professor, who has developed the SUTRA mathematical model to accurately predict the trajectory of the Covid pandemic, on Monday said that there may be no fourth wave in the country.  Prof Maninder Agarwal has based his assessment on the fact that over 90 per cent of India’s population has acquired natural immunity.

At the same time, he cautioned that the fourth wave cannot be ruled out if there is a new mutant that bypasses natural immunity significantly. In an article, Agarwal, a professor in the department of computer science engineering, said there are two major reasons for this conclusion.

The first reason is the level of natural immunity in the country. Natural immunity is defined as the immunity acquired by a previous infection. As per the SUTRA model for India, over 90 per cent of India’s population has acquired natural immunity. This is also validated by data from ICMR surveys that have consistently found the actual number of infected people to be more than 30 times the reported numbers, he said.

Natural immunity acts as a strong protection against infection. In an extensive study done for 36 countries across the world covering all continents and more than half of the world’s population, it was found that the severity of the Omicron wave in these countries was inversely proportional to the level of natural immunity present in them.

Secondly, until now, genome sequencing has not shown any significantly new mutant even in NCR. Only variants belonging to the lineage of Omicron, referred to as BA. 2, BA. 2. 9, BA. 2. 10, and BA. 2. 12, have been detected.

This means that immunity acquired against Omicron will continue to hold against all these variants. With more than 90 per cent of people in India already immune against Omicron, one does not expect any significant fourth wave.

The reason for the increase in the number of Covid cases, according to Agarwal, is that all restrictions have been lifted, and the new variants of Omicron are slightly more infectious.

Both result in a faster spread of the virus among the non-immune population, thereby increasing numbers. This increase is not likely to be substantial though.

He stated that vaccination is excellent in preventing serious illness but not particularly good in preventing mild infection by Omicron.

However, the analysis does not imply that vaccination is not required. Vaccines protect against major illnesses and are extremely useful. Countries that have followed a strict zero-Covid policy are going through a difficult period at present with high infection numbers, for example, South Korea, Hong Kong, and China.

He further said the current situation is not a cause of concern. A fourth wave can only come if there is a new mutant that bypasses natural immunity significantly. Of course, certain precautions are advisable.