Why are some people more at risk of COVID-19 infection than others? New study finds the culprit

The pandemic may be over, but the coronavirus is still lurking around us, trying its best to get into our system. While vaccination certainly offers more protection against the virus, it does not reduce the chances of reinfection to zero. A new study has found that the bacteria living in your nose could be responsible for increasing your risk of COVID-19 infection. Yes, that’s right. Living rent-free and still causing havoc on your health!
A new study from researchers at George Washington University suggests that specific types of nasal bacteria make some people more prone to COVID-19 infection than others. This is because these bacteria could make the respiratory tract more vulnerable to COVID-19. The study is published in

“We’ve known that the virus SARS-CoV-2 enters the body through the respiratory tract, with the nose being a key entry point. What’s new—and surprising—is that bacteria in our noses can influence the levels of proteins that the virus uses to infect cells,” Cindy Liu, associate professor of environmental and occupational health at the GW Milken Institute School of Public Health said in a statement.


Liu and her team examined nasal swab samples from more than 450 people, including those who later tested positive for COVID-19. They zeroed in on two proteins: ACE2 and TMPRSS2, that act like doorways for the virus. ACE2 lets SARS-CoV-2 into nasal cells, while TMPRSS2 helps it activate by slicing its spike protein. The results suggested that people with higher gene expression of these proteins were over three times more likely to catch COVID-19. Even those with moderate levels faced double the risk compared to those with lower expression. The study also found that people who got infected had more unstable levels of gene expression.

Also, women had generally higher levels of gene expression to these proteins, than men, which aligns with the previous studies that COVID-19 infection rates were higher in women. When the researchers looked into the factor that impacted the gene expression, they found the culprit, nasal microbiome. They found that certain nasal bacteria may affect the expression levels of ACE2 and TMPRSS2, influencing the respiratory tract’s susceptibility to COVID-19. They identified three common nasal bacteria linked with it: Staphylococcus aureus, Haemophilus influenzae, and Moraxella catarrhalis/nonliquefaciens. The researchers also found another common type of nasal bacteria, Dolosigranulum pigrum, which was connected to lower levels of these key proteins and may offer some protection against the virus.


The recent study could open new potential ways to predict and prevent COVID-19 infection. “We’re only beginning to understand the complex relationship between the nasal microbiome and our health. This study suggests that the bacteria in our nose—and how they interact with the cells and immune system in our nasal cavity—could play an important role in determining our risk for respiratory infections like COVID-19,” Liu said.