Food allergy is associated with a lower risk of SARS-CoV-2 infection

Press release

Wednesday 1 June 2022

The NIH study finds that high body mass index and obesity increase the risk of infection, but not asthma.

A study funded by the National Institutes of Health found that people with food allergies are less likely to be infected with SARS-CoV-2, the virus that causes COVID-19, than people without them. Additionally, while previous research has identified obesity as a severe risk factor for COVID-19, the new study has identified obesity and elevated body mass index (BMI) as associated with increased risk of SARS infection. -CoV-2. Conversely, the study determined that asthma does not increase the risk of SARS-CoV-2 infection.

The Human Epidemiology and Response to SARS-CoV-2 (HEROS) study also found that children 12 years of age and younger are as likely to be infected with the virus as adolescents and adults, but 75% of infections in children is asymptomatic. Furthermore, the study confirmed that transmission of SARS-CoV-2 within families with children is high. These findings were published today in Journal of Allergy and Clinical Immunology.

“The results of the HEROS study 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 family members from the virus,” he said. said Anthony S. Fauci, MD, director of the National Institute of Allergy, and Infectious Diseases (NIAID), part of the NIH. “Furthermore, the observed association between food allergy and risk of SARS-CoV-2 infection, as well as between body mass index and this risk, deserves further investigation.” NIAID sponsored and funded the HEROS study.

Tina V. Hartert, MD, MPH, co-directed the research with Max A. Seibold, Ph.D. Dr. Hartert is director of the Center for Asthma and Environmental Sciences Research, Vice President for Translational Sciences, Lulu Chair of Medicine H. Owen is a professor of medicine and pediatrics at Vanderbilt University School of Medicine in Nashville. Dr. Seibold is director of computational biology, the Wohlberg and Lambert Endowed Chair of Pharmacogenomics and a professor of pediatrics at the Center for Genes, Environment, and Health at the National Jewish Health in Denver.

The HEROS study team monitored SARS-CoV-2 infection in more than 4,000 people in nearly 1,400 families that included at least one person 21 years of age or younger. This surveillance took place in 12 U.S. cities between May 2020 and February 2021, before the widespread spread of COVID-19 vaccines among non-health workers in the United States and before the widespread emergence of disturbing variants. Participants were recruited from existing NIH-funded studies focusing on allergic diseases. About half of the participating children, adolescents, and adults had a self-reported food allergy, asthma, eczema, or allergic rhinitis.

One caregiver in each family took participants’ nasal swabs every two weeks to test for SARS-CoV-2 and completed weekly surveys. If a family member developed symptoms compatible with COVID-19, additional nasal swabs were taken. Blood samples were also collected periodically and after the first reported illness from a family, if there was one.

When the HEROS study began, preliminary evidence from other research suggested that having an allergic disease could reduce a person’s susceptibility to SARS-CoV-2 infection. HEROS researchers found that having a self-reported, physician-diagnosed food allergy halved the risk of infection, but asthma and other allergic conditions monitored – eczema and allergic rhinitis – were not associated with a reduced risk. of infection. However, participants who reported having a food allergy were allergic to three times as many allergens as participants who did not report having a food allergy.

> Since all of these conditions were self-reported, the HEROS study team analyzed the levels of immunoglobulin E (IgE) specific antibodies, which play a key role in allergic disease, in the blood collected from a subset of participants. According to the researchers, a match between self-reported food allergy and specific IgE measurements for food allergens supports the accuracy of self-reported food allergy among HEROS participants.

Dr Hartert and colleagues speculate that type 2 inflammation, a hallmark of allergic conditions, may reduce the levels of a protein called the ACE2 receptor on the surface of airway cells. SARS-CoV-2 uses this receptor to enter cells, so its scarcity could limit the virus’s ability to infect them. Differences in risk behaviors among people with food allergies, such as eating out less often, could also explain the lower risk of infection for this group. However, through bi-weekly evaluations, the study team found that families with food allergic participants had only slightly lower community exposure levels than other families.

Previous studies have shown that obesity is a risk factor for serious COVID-19. In the HEROS study, the researchers found a strong and linear relationship between BMI – a measure of body fat based on height and weight – and the risk of SARS-CoV-2 infection. Each 10 percentile increase in BMI increased the risk of infection by 9%. Participants who were overweight or obese had a 41% greater risk of infection than those who were not. More research is needed to explain these findings. In this regard, planned analyzes of gene expression in cells collected from participants’ nasal swabs before and after SARS-CoV-2 infection can provide clues to the inflammatory environment associated with the infection, which may change with increasing of BMI, according to the researchers.

The HEROS researchers found that the children, adolescents and adults involved in the study all had a roughly 14% chance of becoming infected with SARS-CoV-2 during the six-month surveillance period. Infections were asymptomatic in 75% of children, 59% of adolescents and 38% of adults. In 58% of participating families where a person was infected, SARS-CoV-2 was passed on to multiple family members.

The amount of SARS-CoV-2 found in nasal swabs, i.e. viral load, varied widely among study participants across all age groups. The viral load range among infected children was comparable to that of adolescents and adults. Given the asymptomatic infection rate in children, a higher percentage of infected children with high viral load may be asymptomatic than infected adults with high viral load.

HEROS investigators concluded that young children can be very efficient SARS-CoV-2 transmitters within the family due to their high rate of asymptomatic infection, their potentially high viral loads and their close physical interactions with members. of the family.

More information about the HEROS study can be found in this 2020 NIAID press release and at under study identifier NCT04375761.

NIAID conducts and supports research – at NIH, in the United States and around the world – to study the causes of infectious and immune-mediated diseases and to develop better means of preventing, diagnosing and treating these diseases. Press releases, fact sheets and other NIAID-related materials are available on the NIAID website.

Information on the National Institutes of Health (NIH):NIH, the nation’s medical research agency, comprises 27 institutes and centers and is a component of the United States Department of Health and Human Services. NIH is the leading federal agency that conducts and supports basic, clinical and translational medical research and is studying the causes, treatments, and cures for common and rare diseases. For more information on NIH and its programs, visit

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MA Seibold et al. Risk factors for SARS-CoV-2 infection and transmission in families with asthmatic and allergic children. A prospective surveillance study. Journal of Allergy and Clinical Immunology DOI: 10.1016 / j.jaci.2022.05.014 (2022).


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