The New York Times reports:

With 1.3 billion people jostling for space, India has always been a hospitable environment for infectious diseases of every kind. And the coronavirus has proved to be no exception: The country now has more than six million cases, second only to the United States.

An ambitious study of nearly 85,000 of those cases and nearly 600,000 of their contacts, published Wednesday in the journal Science, offers important insights not just for India, but for other low- and middle-income countries.

Among the surprises: The median hospital stay before death from Covid-19, the illness caused by the coronavirus, was five days in India, compared with two weeks in the United States, possibly because of limited access to quality care. And the trend in increasing deaths with age seemed to drop off after age 65 — perhaps because Indians who live past that age tend to be relatively wealthy and have access to good health care.

The contact tracing study also found that children of all ages can become infected with the coronavirus and spread it to others — offering compelling evidence on one of the most divisive questions about the virus.

And the report confirmed, as other studies have, that a small number of people are responsible for seeding a vast majority of new infections.

An overwhelming majority of coronavirus cases globally have occurred in resource-poor countries, noted Joseph Lewnard, an epidemiologist at the University of California, Berkeley, who led the study. But most of the data has come from high-income countries.

“It still surprises me that it took until this point for a lot of data to come out of a low- or middle-income country about the epidemiology of Covid,” he said.

In particular, he added, few studies anywhere have done contact tracing at the scale of the study.

“I think it’s some of the most important data we collect in an epidemic in order to decide what kinds of interactions are safe, and what kinds are not,” he said. And yet, “data like this has not really been published very much.”

Though its overall total of cases is huge, the per capita number of cases reported daily in India — and in many other low-income countries, including in Africa — is lower than in Spain, France or even the United States. And its number of deaths has not yet topped 100,000 — which has surprised some scientists.

India “is a place where you would expect a disease like this to roar through, at least in the older populations,” said Dr. Krutika Kuppalli, an infectious disease expert at the Medical University of South Carolina. “They haven’t seen that as much as you would expect.” [Continue reading…]