A vast study in India of nearly 85,000 coronavirus cases and almost 600,000 of their contacts offers some surprising findings and important insights.

By Jonathan Wolfe

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Unexpected findings from India

A vast study in India of nearly 85,000 coronavirus cases and almost 600,000 of their contacts offers some surprising findings and important insights.

Our colleague Apoorva Mandavilli, who covers science, was born in India and lived in both Tamil Nadu and Andhra Pradesh, the two southern states that were the focus of the study — one of the largest to employ contact tracing anywhere to date.

“I was blown away by the extent of the contact tracing that they were able to do because India is a very crowded place,” Apoorva told us. “There are so many markets and jam-packed streets and buildings. Tracing the contacts of a person is hard to do anywhere, but especially in India — it’s really impressive.”

Here are some of the findings she found most surprising.

Children of all ages can become infected with the virus and can spread it to others — offering solid evidence on one of the most divisive questions of the virus.

A small number of people were responsible for seeding a majority of new infections, confirming past research. Overall, 5 percent of people were responsible for 80 percent of infections detected by contact tracing. Most people, 71 percent, did not seem to pass the virus on to anyone else.

Initial infections — known as index cases — were more likely to be among men who were older than their contacts. “I think that says something about who gets to go out and about, and who is more likely to respond to contact tracers,” Apoorva said.

Deaths increased with age but seemed to drop off after age 65, perhaps because life expectancy in India is 69 years, and Indians who live past 65 tend to be relatively wealthy and have access to good health care.

The median stay for Covid-19 patients who died in the hospital was only five days, compared with two weeks in the United States. “That really speaks to a system that abandons its people until they are so sick that they are almost at death’s door,” Apoorva said.

Apoorva also told us that the location of the study should be understood in context.

“These two Indian states have a really rich history of activism and public health, so they are probably best positioned to tackle something like the pandemic,” she said. “This is probably the best-case scenario, and the situation is much more dire in the rest of India — many fewer hospitals, many fewer skilled personnel, many fewer ventilators and I.C.U. units and everything else you need to take care of Covid-19 patients.”

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