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Researchers explain why COVID doesn't make some people sick

COVID-19 sent some people to hospitals while others never got sick. Researchers wanted to know why the virus affects people differently.
Researchers explain why COVID doesn't make some people sick
Posted at 12:43 PM, Jul 19, 2023

More than three years into the pandemic, many Americans still have yet to become ill from COVID-19. Researchers are trying to figure out why a virus has sent millions of people to the hospitals while others haven't become sick at all. 

The answer might be due to genetics. 

According to a group of researchers, including ones from the University of North Carolina at Charlotte and the University of California San Francisco, the answer could be due to genetics. 

The researchers focused on a group of genes called human leukocyte antigens (HLA). According to researchers at UNC Charlotte, these genes act as codes used by the immune system to separate healthy cells from those infected with viruses and bacteria. The researchers wondered what role these genes play in the body's immune response to COVID-19. 

The study enrolled 29,947 people early in the pandemic who were unvaccinated at the time. What they found was those who have a certain generic variant were much more likely to remain asymptomatic even when testing positive for COVID-19. 

SEE MORE: FDA authorizes additional COVID booster shot for certain Americans

This variant, HLA-B*15:01, is found in 10% of the population, researchers said. 

They hypothesized that those with this variant had memory T cells against a specific particle of COVID-19 despite not having direct exposure to the virus. 

"We hypothesized that their immune system could react so fast and powerfully that the virus was eliminated before causing any symptoms. It’s like having an army that already knows what to look for and can tell by the uniform that these are the bad guys," said UNC Charlotte assistant professor Jill Hollenbach, a co-author of the study.

Research in 2022 from various universities, including the University of California San Francisco, suggested that 20% of COVID-19 infections are asymptomatic. 

"It is widely known that other types of coronaviruses have caused seasonal colds for decades. We hypothesized that these individuals were exposed to seasonal coronaviruses in the past, and somehow, individuals specifically carrying HLA-B*15:01 could quickly kill cells infected by SARS-CoV-2 due to cross-reactive immunological responses. So, even if the bad guys changed the uniform, the army would still be able to identify them by their boots or maybe a tattoo on their arms. That is how our immunological memory works to keep us healthy," said Danillo Augusto, assistant professor of biological sciences at the University of North Carolina at Charlotte.

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