A study funded by the National Institutes of Health has 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. In addition, while previous research identified obesity as a risk factor for severe COVID-19, the new study identified obesity and high body mass index (BMI) with an increased risk of SARS-CoV-2 infection. Is. In contrast, 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 or younger were as likely to be infected with the virus as adolescents and adults, but 75% of infections in children are asymptomatic. In addition, the study confirmed that SARS-CoV-2 transmission is higher in homes with children. These findings were published today in Journal of Allergy and Clinical Immunology,
The HEROS study findings underscore the importance of vaccinating children and implementing other public health measures to protect them from becoming infected with SARS-CoV-2, thus protecting children and vulnerable members of their household from the virus “
Anthony S. Fauci, MD, director of the National Institute of Allergy, and Infectious Diseases (NIAID)
“Furthermore, the observed association between body-mass index and this risk, along with the risk of food allergy and infection with SARS-CoV-2, deserves further investigation.” NIAID sponsored and funded the HEROS study.
Tina V. Hartert, MD, MPH, ne Max A. Siebold, Ph.D. co-led the research with. Dr. Hartt is director of the Center for Asthma and Environmental Sciences Research, vice president of translational science, Lulu H. Owen Chair, and Professor of Medicine and Pediatrics at Vanderbilt University School of Medicine in Nashville. Dr. Siebold is director of computational biology, president of pharmacogenomics by Wahlberg and Lambert, and professor of pediatrics at the Center for Genes, Environment and Health at National Jewish Health in Denver.
The HEROS study team monitored SARS-CoV-2 infection in more than 4,000 people in nearly 1,400 homes, including at least one person aged 21 years or younger. The surveillance took place in 12 US cities between May 2020 and February 2021, before the widespread rollout of COVID-19 vaccines among non-healthcare workers in the United States and the widespread emergence of various forms of anxiety. Participants were recruited from existing, NIH-funded studies that focused on allergic diseases. Roughly half of the participating children, adolescents, and adults had self-reported food allergies, asthma, eczema, or allergic rhinitis.
A caregiver in each home took participants’ nasal swabs every two weeks to test for SARS-CoV-2 and filled out a weekly survey. If a household member develops symptoms consistent with COVID-19, additional nasal swabs are taken. Blood samples were also collected from time to time and after the first illness of the family, if any.
When the HEROS study began, preliminary evidence from other research suggested that having an allergic disease might reduce a person’s susceptibility to SARS-CoV-2 infection. HEROS investigators found that self-reported, physician-diagnosed food allergies halved infection risk, but monitored asthma and other allergic conditions — eczema and allergic rhinitis — were not associated with reduced infection risk Were. However, participants who reported having food allergies were three times more likely to have allergies than participants who did not report having food allergies.
Since all of these conditions were self-reported, the HEROS study team analyzed the levels of immunoglobulin E (IgE)-specific antibodies, which play an important role in allergic disease, in blood collected from a subset of participants. According to the investigators, a correspondence between self-reported food allergies and food allergen-specific IgE measurements supports the accuracy of self-reported food allergies among HEROS participants.
Dr. Hartert and colleagues speculate that type 2 inflammation, a feature of allergic conditions, may reduce 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 lack may limit the virus’s ability to infect them. Differences in risk behaviors among people with food allergies, such as eating less frequently at restaurants, may also explain the lower infection risk for this group. However, through biweekly assessments, the study team found that households with food-allergy participants had only slightly lower levels of community exposure than other households.
Previous studies have shown that obesity is a risk factor for severe COVID-19. In the HEROS study, investigators found a strong, linear relationship between BMI — a measure of body fat based on height and weight — and the risk of SARS-CoV-2 infection. Every 10-point increase in BMI percentile increased the risk of infection by 9%. The risk of infection among participants who were overweight or obese was 41% higher than in those who were not. More research is needed to explain these findings. In this regard, the planned analysis of gene expression in cells collected from nasal swabs of participants before and after SARS-CoV-2 infection may provide clues about the infection-associated inflammatory environment, which according to the investigators increases BMI. may change.
The HEROS researchers found that the children, adolescents, and adults in the study had about a 14% chance of SARS-CoV-2 infection during the six-month monitoring period. Infection was asymptomatic in 75% of children, 59% of adolescents and 38% of adults. In 58% of participating households where one person became infected, SARS-CoV-2 was transmitted to multiple household members.
The amount of SARS-CoV-2 detected in nasal swabs, that is, the viral load, varied widely among study participants across all age groups. The viral load range in infected children was comparable to that of adolescents and adults. Given the rate of asymptomatic infection in children, a greater proportion of infected children with higher viral loads may be asymptomatic than infected adults with higher viral loads.
The HEROS investigators concluded that young children may be very efficient SARS-CoV-2 transmitters within the home, because of their high rates of asymptomatic infection, their potentially high viral loads, and their close physical interactions with family members.
More information about the HEROS study is available in this 2020 NIAID press release and at clinicaltrials.gov under study identifier NCT04375761.
National Institutes of Health
Siebold, MA, and others. (2022) Risk factors for SARS-CoV-2 infection and transmission in families with children with asthma and allergies. A prospective surveillance study. Journal of Allergy and Clinical Immunology, doi.org/10.1016/j.jaci.2022.05.014.