People with food allergies seem to be less likely to contract SARS
Since the beginning of the pandemic, researchers have been trying to determine who is most at risk of contracting SARS-CoV-2, and why.
Today, a new population study by the National Institutes of Health (NIH) has highlighted a peculiar benefit of the coronavirus for people with allergies.
In an analysis of more than 4,000 people living in homes with minors, researchers noted several intriguing trends in SARS-CoV-2 infection, including that people with food allergies were half as likely to become infected.
These findings are consistent with other recent research, which suggests that allergic conditions, such as asthma, may offer some protection against severe cases of COVID-19.
Along the same lines, the new NIH study showed that asthma was not associated with an increased risk of SARS-CoV-2 infection, even though asthma is a disease that affects the respiratory system.
In contrast, obesity and high BMI were factors that increased the risk of SARS-CoV-2 infection, as was the age of children and adolescents sharing the same living space.
But discovering a food allergy may be the most important discovery.
“The observed association between food allergy and risk of SARS-CoV-2 infection, as well as between BMI and this risk, deserves further investigation,” says Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
Researchers aren’t entirely sure why food allergies make people less likely to get SARS-CoV-2, but there are some possible explanations.
Half of the study participants said they had been diagnosed with a food allergy, asthma, eczema or allergic rhinitis. These statements were later confirmed by a subset of blood tests, which revealed the presence of antibodies associated with allergic diseases.
The researchers then tracked the spread of SARS-CoV-2 in the participants’ homes from May 2020 to February 2021.
People with eczema and asthma did not show additional vulnerability to the virus, but they also did not appear to be more protected.
On the other hand, people with food allergies have a 50% lower risk of contracting SARS.
Not all forms of asthma are atopic (that is, hypersensitive), and previous studies have shown that only people with atopic asthma have lower levels of ACE2 receptors in the airways, to which CoV-2 binds.
This indicates that the virus does not have many ways to invade the cells in the lungs of people with respiratory allergies.
A similar phenomenon can occur in people with food allergies, although the authors only looked at SARS-CoV-2 infection, not the severity of the infection.
“It is unclear whether this is also the case in people with food allergies, but it is tempting to speculate that type 2 inflammation, a hallmark of food allergy, may reduce ACE2 levels in the respiratory tract, and thus risk of infection,” write.
“To support this possibility, we found significantly higher levels of generalized atopy in people who reported a food allergy, compared to people without a food allergy, and even people with asthma.”
Interestingly, while some studies suggest that allergic asthma protects against severe cases of COVID-19, the current study shows that this condition does not protect against initial contraction of the virus.
Also, when a participant with asthma or a food allergy contracted the new coronavirus, they were not likely to be asymptomatic.
More research is needed to unravel the mechanisms behind these new findings, but the authors hope their work offers new ways to prevent COVID-19.
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