Most risk factors for severe Covid courses are known. These include diabetes, obesity and other pre-existing conditions. As US researchers have now found out, there are also comorbidities that apparently protect against infection: food allergies.
They wanted to find out how easily the corona virus spreads in households: US researchers have accompanied more than 1,000 families in recent years and analyzed the members’ risk of infection. They were not only able to draw conclusions about the risk of certain age groups. They also found that allergy sufferers were apparently much less likely to become infected. Another group, on the other hand, had a significantly increased risk of infection.
Researchers at the National Institute of Allergy and Infectious Diseases followed around 1,400 households from the beginning of the pandemic until February 2021. Every two weeks, they took nasal swabs from around 4,000 residents and tested them for Sars-CoV-2. In doing so, they discovered a surprising connection: certain allergy sufferers were much less likely to become infected with Corona than other people. Previously, there had only been preliminary indications of such a connection.
The scientists found that having a “self-reported, doctor-diagnosed food allergy halved the risk of infection,” according to a statement. In order to support this data, the researchers also determined allergy-specific antibodies in the blood of those affected. In this way, they were able to verify the self-reported allergies and substantiate the results.
The scientists have also found a possible explanation for the halved risk of infection: what is known as type 2 inflammation is characteristic of allergies. These can trigger both food allergies and diseases such as neurodermatitis, but also allergic asthma. According to the researchers, it is precisely this inflammation that causes the concentration of ACE2 receptors in the airway cells to drop. However, it is precisely these receptors that the coronavirus needs to get into human cells. So the allergy could make it harder for the virus to infect cells. Scientists have already found evidence of such a connection in laboratory studies.
In addition, the researchers speculated whether a change in risk behavior in this group could also play a role. So whether people with food allergies ate less often in restaurants than others. However, the scientists determined with the help of a two-week survey that there were hardly any differences to non-allergic people.
Instead, the risk of infection was significantly increased in people with obesity. So far, researchers only knew that the disease increases the risk of severe courses – but according to the new data, apparently also for the infection itself. The scientists found a “strong, linear relationship” between the BMI and the risk of corona infection. Accordingly, the risk of infection increased – by nine percent with every increase in BMI by ten points. People who were overweight or obese had a 41 percent higher risk of infection.
A possible explanation could be that overweight people have more ACE2 receptors. In order to explain these results comprehensively, the scientists need further investigations.
The researchers found another exciting connection: According to their investigations, the risk of infection for asthmatics was not increased. This is interesting insofar as asthmatics could theoretically be part of the risk group due to their already strained airways. However, that was not the case.
The researchers published their findings in the Journal of Allergy and Clinical Immunology. According to their own statements, these should help to prevent future infections better and in a more targeted manner.
