Obesity, age and COVID-19 infection can make a person highly susceptible to SARS-CoV-2

Scientists and public health experts have long known that some individuals, known as “super-spreaders,” can promote COVID-19 with amazing effectiveness and tremendous results.

Now, researchers at Tulane University, Harvard University, MIT and Massachusetts General Hospital have found that obesity, age, and COVID-19 infection are linked to increased droplets. respiratory – major carriers of SARS-CoV-2, the virus that causes COVID-19. Their findings were published in Proceedings of the National Academy of Sciences.

Using data from a observational study of 194 healthy individuals and an experimental study of non-human primates with COVID-19, researchers found that large differences in exhaled aerosol vary significantly between subjects. Older ones with higher body mass indexes (BMI) and a higher rate of COVID-19 infection had three times the number of exhaled respiratory drops than the others in the study groups.

The researchers found that 18% of human subjects made up 80% of the exhaled granules in the group, exhibiting a circulation of exhaled aerosol granules that follow the 20/80 rule seen in infectious diseases. other – means that 20% of people with a disease account for 80% of outbreaks.

Aerosol droplets in nonhuman primates increased as COVID-19 infection progressed, reaching peak levels one week after infection before falling to normal after two weeks. Notably, as infection with COVID-19 progressed, viral particles became smaller, reaching the size of one micron at the height of the infection. Small grains are more likely to be excreted when people are breathing, talking or coughing. They can also stay much longer, travel farther in the air and penetrate deeper into the lungs when inhaled.

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

We have seen a similar increase in droplets at the stage of infectious infection with other infectious diseases such as tuberculosis. It appears that viral and bacterial infections of the airway can weaken airway mucus, which stimulates the movement of infectious particles into this environment. “

Chad Roy, PhD, Director, Infectious Disease Aerobiology, Tulane National Priority Research Center

The generation of respiratory depression in the airways varies between people according to their body composition, said lead author David Edwards, PhD, a professor of biochemical engineering practice at Harvard University.

“While our findings show that the younger and healthier ones tend to produce far fewer drops than the older and less healthy ones, they also show that one can any of us, when we have COVID-19, are at risk of producing a large number of respiratory droplets, “Edwards said.