Science

Laxity, emergence of more dangerous variants led to second wave, show studies

TV Jayan New Delhi | Updated on June 09, 2021

A health worker administers a Covid-19 vaccine to a student at a vaccination centre organised for students traveling abroad for higher studies in Hyderabad. (file photo)   -  PTI

 

An overestimation that around 60 per cent of Indians have been exposed to SARS-CoV2 virus by the end of the first wave and a misplaced feeling that there was something that was protecting Indians against the deadly virus led to a laxity which along with the emergence of more infectious strains fueled flare-up during the second wave, according to multiple studies by Indian scientists last week.

 

Those exposed to virus

For instance, one study posted on the pre-print server MedrXiv by researchers from a host of institutions, including the Institute of Mathematical Sciences (IMSc), Chennai; Indian Institute of Science (IISc), Bengaluru; and Ashoka University at Sonepat, among others, estimated that only 40 per cent of Indians were exposed to the virus till February, against 60 per cent projected by a supermodel developed by a team supported by the Department of Science and Technology.

“Results from the DST supermodel had suggested that herd immunity, defined as 60 per cent or so in actual numbers of infected, might have been attained by November 2020. They predicted that the pandemic would itself vanish by February 2021,” said Gautam Menon, Professor of Physics and Biology at Ashoka University.

“Our work shows that, far from this being the case, it is likely that only about 40 per cent India-wide had been infected by February. The fact that there was a large reservoir of those who remained to be infected might also help account for the rapid rise and impact of the second wave,” said Menon, who is also associated with IMSc.

This sea of humanity was sitting duck for the new variants emerged on the scene as shown by another research team, which looked at the sudden surge in Covid-19 cases in Delhi in April and May.

The paper by researchers associated with the Indian SARS-CoV2Genomic Consortium (INSACOG) and Institute of Genomics and Integrative Biology (IGIB) in New Delhi showed the cases in Delhi started going up with the entry of the B.1.1.7 (first reported in the UK in September last year), subsequently by B.1.167 variant, also highly transmissible, and subsequently by B.1.167 sub-lineage, B.1.167.2, which was found not only more infectious but also capable of escaping immune response.

According to Anurag Agrawal, IGIB Director, and a key authors of the paper, B.1.167.2 was more transmissible than B.1.167 and has the ability to escape immune response and reinfect people. Vaccines have reduced efficacy against infection by B.1.167.2 compared to B.1.167, said Agrawal, hinting that this would explain why many vaccinated people contracted the infection, albeit milder ones. Menon and his multi-institution team, which developed an independent model to study the pandemic right at the beginning, estimated that India would have undercounted deaths in the country by a factor of 2.2 during the first wave. Officially confirmed Covid-19 deaths in India till January 31 were 1,54,428.

Underreporting cases

The study also found that India was underreporting cases by almost 90 per cent in the initial days of the pandemic, which went down significantly to 20 per cent by the end of the first wave.

“It is certainly clear that there was simply not enough testing going on in the initial phase of the epidemic, the first wave. Since the government had not recognised the existence of community transmission – in fact, it still doesn’t – it is clear that many of those who should potentially have been tested did not qualify for testing over the first 2-3 months of the epidemic,” said Menon.

Published on June 08, 2021

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