Why India didn’t suffer second wave of Covid-19 pandemic

Gyaneshwar Chaubey, a professor of genetics at Varanasi’s Banaras Hindu University (BHU), may have an answer why India didn’t suffer a second wave of Covid-19 pandemic, unlike many countries that suffered multiple waves, some of them more severe than the earlier ones.

Chaubey’s team from BHU’s Cytogenetics Laboratory collaborated from their counterparts from multiple institutions across the country and looked the presence of antibodies against SARS-CoV2 virus, in blood samples of over 2,300 people who never contracted the infection or hailed from families where there was no Covid-19 cases. These volunteers were drawn from all regions – eastern, central, western, northern and southern – of the country.

Key reason

Yet to be peer-reviewed work of the scientists showed every third or fourth person in the country is harbouring antibodies against the infection, pushing India towards a soft herd immunity. “This could probably explain why the cases were coming down gradually in the country,” Chaubey told BusinessLine from Varanasi. The scientists posted their work in medRxiv recently.

The Covid-19 cases in India peaked in September and since then the number of cases have been dropping substantially. As against close to 1 lakh daily cases in end September, India on Wednesday reported around 11,000 new cases.

“This explains why the virus couldn’t go further. The chain of the virus is broken as majority of people (who are seemingly uninfected) are already immune to the virus,” he said. For the study, the team chose volunteers who are more exposed in the society such as roadside workers, roadside fruit-vegetable hawkers, rickshaw pullers, autorickshaw drivers and milkmen in urban areas in 14 districts across the country. For instance, they identified samples from two districts in Gujarat, seven districts in Uttar Pradesh, three districts from Madhya Pradesh and Chhattisgarh, one district each from Karnataka and West Bengal, representing all major regions in the country. Among these districts, Varanasi, Jaunpur and Ghazipur in eastern Uttar Pradesh found to have higher seroprevalence of nearly 0.4, that is two in every five persons have immunity against the infection.

An earlier paper from Chaubey’s team explained why despite this widespread exposure, a large number of Indians did not fall sick. In a paper published Frontiers in Genetics journal in September, they showed that nearly 60 per cent of Indians harbour a variation in the gene ACE2, which codes for the enzyme Angiotensin-Converting Enzyme 2, which is hijacked by the virus to gain an entry into human cells. It is this same variation that saved South-East Asians too from a major Covid-19 onslaught.

Frequency of gene variation

The team had found that the frequency of this gene variation ranged from 80 to 100 per cent in people living in North-East India to nearly 30 per cent in western parts of the country. Other populations came in between. “This correlates very well with the case and fatality rates reported in different parts of the country,” Chaubey said.

This, according to him, would have probably helped a large chunk of Indians who would have been exposed to the virus, remain asymptomatic nonetheless. Another factor that could have saved Indians would also be the fact that 65 per cent of Indians are below the age of 35 years, he observed.

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