Researchers unravel what makes someone a COVID-19 super distributor

Public health scientists and experts have long known that certain individuals, called ‘super-distributors’, can transmit COVID-19 with incredible efficacy and devastating consequences.

Now, researchers from Tulane University, Harvard University, MIT and Massachusetts General Hospital have learned that obesity, age and COVID-19 infection are linked to the tendency to exhale more respiratory drops – the main distributors of SARS-CoV-2, the virus. causing COVID-19. Their findings were published in 2008 Proceedings of the National Academy of Sciences.

Using data from an observational study of 194 healthy humans and an experimental study of non-human primates with COVID-19, researchers found that exhaled aerosol particles varied widely between subjects. Those who were older with higher body mass indices (BMI) and an increasing degree of COVID-19 infection had three times the number of exhaled drop drops than others in the study groups.

Researchers have found that 18% of human subjects make up 80% of the exhaled particles in the group, reflecting a distribution of exhaled aerosol particles that follows the 20/80 rule seen in other infectious disease epidemics – which means that 20% of the infected individuals are responsible for 80% of the broadcasts.

Aerosol drops in non-human primates increased as COVID-19 infection progressed, reaching peak levels one week after infection before returning to normal after two weeks. As infection with COVID-19 progressed, viral particles became smaller and reached the size of a single micron at the peak of infection. Small particles are more likely to be expelled when people breathe, talk or cough. They can also stay afloat for much longer, move further in the air and penetrate deeper into the lungs when inhaled.

The increase in exhaled aerosols has even occurred among those with asymptomatic cases of COVID-19, said Chad Roy, Ph.D., corresponding author and director of aerobiology infectious diseases at the Tulane National Primate Research Center.

“We have seen a similar increase in drops during the acute infection stage with other infectious diseases such as tuberculosis,” Roy said. “It seems likely that viral and bacterial infections in the airways can weaken airway mucus, which promotes the movement of infectious particles to this environment.”

The generation of respiratory droplets in the airways varies between people, depending on their body composition, says lead author David Edwards, Ph.D., professor of biomedical engineering at Harvard University.

“While our results show that young and healthy tend to produce far fewer drops than the older and less healthy, it also shows that any of us, when infected by COVID-19, run the risk of a large number to produce respiratory drops., ‘Edwards said.