Some Allergies Associated With Lower Risk of SARS-CoV-2 Infection

An NIH study found that food allergies reduced risk of infection by 50 percent

An electron microscope image of of SARS-CoV-2
 Researchers speculate that type two inflammation that occurs in allergic conditions may reduce levels of the ACE2 receptor on the surface of airway cells, where SARS-CoV-2’s spike protein binds to. (Pictured: Novel Coronavirus SARS-CoV-2 under and electron microscope) NIAID

A new study from the National Institutes of Health (NIH) found that those with food allergies are 50 percent less likely to become infected with SARS-CoV-2. Along with the new finding, the research also found that obesity and a high body mass index (BMI) are factors for an increased risk for SARS-CoV-2 infection and that asthma or eczema did not increase the risk for infection, an NIH statement explains. Details on the study were published last month in the Journal of Allergy and Clinical Immunology

Researchers analyzed 4,000 people in 1,400 households, including minors, in the Human Epidemiology and Response to SARS-CoV-2 (HEROS) study. They noticed that individuals with a food allergy were about half as likely to become infected, reports Carly Cassella for Science Alert. Along with these findings, the HEROS data found that children 12 years or younger are just as likely to become infected with the virus as teens and adults (75 percent of infections in the children were asymptomatic). Data was collected between May 2020 and February 2021, before the widespread roll-out of Covid-19 vaccines among non-healthcare workers in the United States and before the widespread emergence of various variants of the virus, per a statement. The research also found that allergic conditions like asthma, despite being a respiratory illness, may offer some protection against severe cases of Covid-19.

"The HEROS study findings underscore the importance of vaccinating children and implementing other public health measures to prevent them from becoming infected with SARS-CoV-2, thus protecting both children and vulnerable members of their household from the virus," says Anthony S. Fauci, M.D., director of the National Institute of Allergy, and Infectious Diseases (NIAID) in a statement.

Half of the study participants stated that they were diagnosed with either a food allergy, asthma, eczema or allergic rhinitis—conditions that were confirmed by blood tests. Researchers then tracked SARS-CoV-2 infections among households by taking nasal swabs of participants every two weeks and filling out weekly surveys. If a participant developed symptoms of Covid-19, more nasal swabs and blood samples were taken, a statement explains. The team found that household transmission of SARS-CoV-2 was lower in homes with individuals with food allergies, according to the study. 

Researchers speculate that type two inflammation—a normal immune response that can occur in response to infections or parasites but also occurs in allergic conditions like eczema and some asthmas—may reduce levels of the ACE2 receptor on the surface of airway cells. ACE2 is the receptor that the SARS-CoV-2’s spike protein binds to, allowing the virus to enter cells. Having fewer ACE2 receptors limits the virus's ability to infect, per a statement. More research is needed to identify what other mechanisms may play a role in reducing the risk of viral infection, per Science Alert.

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