Superspreader led to 60% of Covid-19 cases: Study-Indian News

One-tenth of all patients infected with coronavirus disease (Covid-19) become “superspreaders,” accounting for 60% of new infections and 70% of infected patients do not infect others. Sars-CoV-2 published in the journal Science — The axioms most people accept are the first to be numbered.

Probably the largest Covid-19 epidemiological analysis conducted in the world, a contact tracing study exposed at least 85,000 confirmed cases of Covid-19 in two Indian states (Andhra Pradesh and Tamirnadu). We investigated the transmission patterns of the disease in 575,000 people.

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The study also demonstrated that children are the “active senders” of Covid-19.

A group of researchers led by Ramanan Laxminarayan, director of the Washington-based Center for Disease Dynamics, Economics and Policy (CDDEP), also found high case fatality (CFR) in the 40-69 age group. India is closer than any other seriously affected country and its proximity travel is one of the highest risk behaviors for Covid-19 infection.

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However, the tendency for CFR declines after the age of 80, when India is in line with other countries. Experts say that selection bias is the cause of Indians who live past that age because they can fight in good health. Make the illness better.

A study published in Science, “Epidemiology and Infectious Dynamics of COVID-19 in Two Indian States,” also found that the median length of stay before death from Covid-19 in the two states was 13 days, compared to It turned out to be about 5 days. In the United States.

Transmission coefficient

One of the key findings of the report was the large variability in the number of people infected with the virus. Many were not infected by anyone, but a few “superspreaders” were involved in most of the new infections. .. Of the 88,616 first-episode patients studied in the report, 70.7% did not infect anyone else, the researchers found.

On the other side of the spectrum, proband follow-up tests revealed that 8% of probands accounted for 60% of the new infections observed. Researchers say this is the largest recorded demonstration of the “Superspreader.”

“Superspreaders are often mistaken for just an event. In our study, about one-tenth of the population of infected individuals is far more likely to infect the virus than others. This probably plays a big role in all countries, not just India, “said Lakshmi Narayan, lead author of the study.

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In fact, most experts have embraced the role of superspreaders, but so far no studies have quantified their effects.

The analysis categorized all contacts into high-risk and low-risk incidents. If people shared a home and made close or direct physical contact with the proband, they were considered high-risk contact. Low-risk contacts were those who did not meet high-risk exposure criteria and shared the same space (such as a room) with the proband. We also investigated the types and settings of interactions that caused Covid-19 infection.

Proximity travel (sharing a closed space in a car or bus) has the highest risk of infecting others and shows a “secondary incidence” (SAR) (percentage of all contacts tested). It was. Positive — 79.3%.

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In addition, the prevalence of infection is high among children who are contacts of cases around the same age, with children aged 5 to 17 being the most likely to infect other children. understood. For every 100 first-episode patients aged 5 to 17 years, 15.4 contacts were positive, the highest percentage of the age group analyzed. People between the ages of 18 and 39 were in the second place, both infected with 12.3% of their contacts.

“We have underestimated the role of children as an important part of the transmission chain. This is done outside the home while reopening school and while children infect people in the home with the virus. It affects situations where you are more likely to get infected, “says Laxminarayan.

Experts said the concept of superspreaders gives the general public more reason to pay attention to factors such as mask hygiene.

“A small percentage of infected people spread the disease further, and most people do not or hardly spread the virus at all. This is in India, where data confirm that the superspreader effect is widespread. This is the first study of the virus. What it means to us is that no one really knows that the person they meet will be a superspreader, so you will have to keep wearing the mask tightly and pay more attention to it. It will be important, “said a virologist and Faculty of Biological Sciences, Ashoka University.