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A study of more than half a million people in India who were exposed to the new coronavirus SARS-CoV-2, or COVID-19, suggests that the continued spread of the virus is driven by only a small percentage of those who become infected.
Additionally, children and young adults were found to be potentially much more important in transmitting the virus, especially within homes, than previous studies have identified, according to a paper by researchers from the United States and India published Sept. 30. in the magazine. Sciences.
Researchers from the Princeton Environmental Institute (PEI), Johns Hopkins University, and the University of California-Berkeley worked with public health officials in Southeastern India’s Tamil Nadu and Andhra Pradesh states to trace infection pathways. and the death rate of 575,071 people who were exposed to 84,965 confirmed cases of SARS-CoV-2.
It is the largest contact tracing study, which is the process of identifying people who came into contact with an infected person, carried out in the world for any disease.
Lead Investigator Ramanan Laxminarayan, PEI Principal Investigator, said the paper is the first large study to capture the extraordinary extent to which COVID-19 relies on “super spread,” in which a small percentage of the infected population transmits the virus aa more people.
The researchers found that 71% of infected people did not infect any of their contacts, while only 8% of infected people accounted for 60% of new infections.
Our study presents the largest empirical demonstration of superpropagation that we know of in any infectious disease. Over-spreading events are the rule rather than the exception when looking at the spread of COVID-19, both in India and probably all affected places. “
Ramanan Laxminarayan, study principal investigator and principal investigator, Princeton Environmental Institute
The findings provide a broad view of the spread and fatality of COVID-19 in countries such as India, which has experienced more than 96,000 deaths from COVID-19, which have a high incidence of populations with limited resources, the researchers reported.
They found that coronavirus-related deaths in India occurred, on average, six days after hospitalization compared to an average of 13 days in the United States. Additionally, coronavirus deaths in India have been concentrated among people aged 50 to 64, which is slightly younger than the population at risk over 60 in the United States.
However, the researchers also reported the first large-scale evidence that the implementation of a nationwide shutdown in India led to substantial reductions in coronavirus transmission.
The researchers found that the chances of a person with coronavirus, regardless of age, transmitting it to close contact ranged from 2.6% in the community to 9% at home. The researchers found that children and young adults, who made up a third of COVID cases, were especially key to transmitting the virus in resource-limited populations.
“Children are very efficient transmitters in this environment, which is something that has not been firmly established in previous studies,” Laxminarayan said. “We found that reported cases and deaths have been more concentrated in younger cohorts than we expected based on observations in higher-income countries.”
Children and young adults were much more likely to contract the coronavirus from patients their own age, the study found. Overall, contacts of the same age in all age groups greatly increased the chance of infection, with the likelihood of contracting coronavirus from low- to high-risk contacts ranging from 4.7% to 10.7%, respectively.
Source:
Magazine reference:
Laxminarayan, R., et al. (2020) Epidemiology and transmission dynamics of COVID-19 in two states of India. Sciences doi.org/10.1126/science.abd7672.
