Scientists unravel what makes some people COVID-19 super-spreaders

Obesity, , and state of COVID-19 infection influence number of virus particles an infected person breas out, according to a new study which says se factors determine if a person becomes a super-spreer of virus. observational study, published in journal PNAS, assessed 194 healthy people and also examined findings of an experimental study of nhuman primates with COVID-19.

According to researchers, including those from Harvard University in US, exhaled aerosol particles vary greatly between subjects, depending on ir , state of viral infection, and body mass index (BMI). Body mass index is ratio of a person's weight to square of ir height in metres, and scientists said older people with a higher BMI and an increasing degree of COVID-19 infection h three times number of exhaled respiratory droplets as ors in study groups.

analysis revealed that 18 per cent of human subjects accounted for 80 per cent of exhaled particles of group -- reflecting a distribution of exhaled aerosol particles that follows 20/80 rule. According to this rule, which is seen in or infectious disease epidemics, 20 per cent of infected individuals are responsible for 80 per cent of transmissions.

scientists also found that aerosol droplets in nhuman primates increased as infection with COVID-19 progressed, reaching peak levels a week after infection before falling to rmal after two weeks. As infection with COVID-19 progressed, y said viral particles got smaller, reaching size of a single micron at peak of infection.

se tiny particles, researchers said, are more likely to be expelled as people brea, talk or cough and can also stay afloat much longer, travel farr in air and penetrate deeper into lungs when inhaled. y said increase in exhaled aerosols occurred even among those with asymptomatic cases of COVID-19.

"We've seen a similar increase in droplets during acute infection st with or infectious diseases like tuberculosis," said Ch Roy, a co-author of study from Tulane National Primate Research Center in US.

"It seems likely that viral and bacterial infections of airway can weaken airway mucus, which promotes movement of infectious particles into this environment," Roy said.

While findings suggested that young and healthy people tend to generate far fewer droplets than older and less healthy, researchers cautioned that any individual, when infected with coronavirus, may be at risk of producing a large number of respiratory droplets. y said furr studies are needed to determine or factors which may influence quantity of virus particles an infected person may spre. "Understanding source and variance of respiratory droplet generation, and controlling it via stabilization of airway lining mucus surfaces, may le to effective approaches to reducing COVID-19 infection and transmission," scientists wrote in study.