Coronavirus super-spreaders were behind the Covid-19 explosion in India, the country with the most cases after the United States, the researchers said.
A group of patients that included about 8% of India’s confirmed cases later led to nearly two-thirds of their total infections, scientists said Wednesday in a study published in the journal. Sciences. The research, based on tracing more than 3 million contacts in the southern states of Andhra Pradesh and Tamil Nadu as of August 1, is the first major transmission study in a developing country.
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While most research on the pandemic has come from China, Europe and North America, cases are now increasing in India and other developing countries, according to researchers led by Ramanan Laxminarayan, director of the Center for Dynamics, Economics and Disease Policy who wrote the study. . Barriers to health care are higher in these nations, and the risk of becoming seriously ill and dying from Covid is higher, they said.
“We’ve never had this degree of information to say, hey, some people are really spreading the virus in a massive way,” Laxminarayan said in an interview. In contrast to the minority of super spreaders, 71% of confirmed cases whose contacts were traced were not found to have transmitted the virus to anyone.
A nationwide serosurvey showed that one in 15 Indians has been exposed to the coronavirus. Hospitals in several states are now struggling to secure medical oxygen, necessary to help patients with breathing problems on their own.
Data for the Science study was collected by thousands of contact trackers during the India shutdown, when mass gatherings were banned, schools were closed and people were ordered to wear masks in public. Almost 130 million people live in the two states of India, representing approximately 10% of the country’s population. India has registered more than 6.2 million cases of Covid-19.
Prolonged close contact
Both states reported their first SARS-CoV-2 infections on March 5. Health workers tracked up to 80 contacts per confirmed case, using improved skills and resources to routinely track potential transmitters of HIV and tuberculosis, Laxminarayan said.
The prolific transmitters of SARS-CoV-2 tended to spread the virus during prolonged close contact on buses and other forms of transportation, according to the researchers, who were also from Princeton University, the Johns Hopkins Bloomberg School of Public Health and the state governments of India. In such settings, there was a 79% chance that an infection would occur.
That compares with a 1 in 40 chance of contracting the virus from someone in the community who is not a household member, Laxminarayan said. However, children under the age of 14 were found to be frequent “silent” transmitters of the virus, especially to their parents and peers.
“This shows that even without schools running, child-to-child transmission appears to be quite important,” he said. “As terrible as it is to say, with two children at home, it is actually important to keep the children at home.”
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