Indian super-spreaders have driven rapid rise in coronavirus cases, researchers say

A nationwide serological survey showed that one in 15 Indians have been exposed to the coronavirus, suggesting total cases may exceed the official tally

Hospitals in several states are now struggling to secure medical oxygen, needed to assist patients with trouble breathing on their own

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An Indian health worker takes a nasal swab sample during coronavirus testing on the outskirts of Gauhati. Photo: AP

Published: 10:32am, 1 Oct 2020Updated: 10:41pm, 1 Oct 2020

Coronavirus super-spreaders were behind the explosion of Covid-19 in India, the country with the most cases after the US, researchers said.

A group of patients that included about 8 per cent of India’s confirmed cases later led to almost two-thirds of its total infections, scientists said on Wednesday in a study published in the journal Science. The research, based on tracing more than 3 million contacts in the southern states of Andhra Pradesh and Tamil Nadu through August 1, is the first major study of transmission in a developing country.

While most research on the pandemic has come from China, Europe and North America, cases are now burgeoning in India and other developing countries, according to researchers led by Ramanan Laxminarayan, director of the Centre for Disease Dynamics, Economics & Policy who wrote the study. Barriers to health care are greater in these nations, and the risk of getting severely ill and dying from Covid is higher, they said.

“We’ve never had this degree of information to say, hey, some people are really transmitting the virus in a massive way,” Laxminarayan said in an interview. In contrast with the super-spreader minority, 71 per cent of confirmed cases whose contacts were traced weren’t found to have spread the virus to anyone.

A nationwide serological survey showed that one in 15 Indians have been exposed to the coronavirus. Hospitals in several states are now struggling to secure medical oxygen, needed to assist patients with trouble breathing on their own.

Data for the Science study were gathered by thousands of contact-tracers during India’s lockdown, when mass gatherings were banned, schools were closed and people were ordered to wear face masks in public. Almost 130 million people live in the two Indian states, accounting for about 10 per cent of the country’s population. India has recorded more than 6.2 million Covid-19 cases.

Both states reported their first Sars-CoV-2 infections on March 5. Health workers traced as many as 80 contacts per confirmed case, using skills and resources honed from routinely tracking potential transmitters of HIV and tuberculosis, Laxminarayan said.