What you need to know

Since the early months of the pandemic, researchers have sought links between conditions that weaken or disrupt the immune system and the likelihood of getting COVID-19. In a new study supported by the National Institute of Allergy and Infectious Diseases (NIAID), researchers found that people with food allergies are less likely to become infected with SARS-CoV-2, the virus that causes COVID-19, than people with no food allergies.

Researchers also discovered a relationship between high body mass index ­­(BMI), a measure of body fat based on height and weight, and an increased risk for SARS-CoV-2 infection. In addition, researchers determined that children age 12 or younger are just as likely to become infected with the virus as teenagers and adults.

What did the researchers do?

As part of the Human Epidemiology and Response to SARS-CoV-2 (HEROS) study, researchers monitored more than 4,000 people in nearly 1,400 households that included at least one person 21 years old or younger. A caregiver in each household took nasal swabs of participants every two weeks, and blood samples were collected periodically.

Researchers found that people who reported having a physician-diagnosed food allergy had a 50% lower risk of infection. Participants who were overweight or obese were 41% more likely to be infected. For each 10-point increase in a person’s BMI, their risk of SARS-CoV-2 infection rose by 9%.

HEROS researchers also found that although adults, teenagers, and children had similar infection rates, 75% of children (under age 13) infected with SARS-CoV-2 were asymptomatic, compared with 59% of infected teenagers (ages 13 to 21) and 38% of infected adults. The amount of SARS-CoV-2 found in nasal swabs — known as the viral load — was similar among children, teenagers, and adults. This means a larger percentage of infected children with high viral loads may be asymptomatic relative to adults.

Why is this research important?

Although further research on the relationship between food allergies and SARS-CoV-2 infection is needed, identifying how food allergies are related to a lower risk of infection can help determine effective measures to prevent infection. In addition, previous research has shown that obesity is associated with severe COVID-19, and these new findings add to that line of research by linking obesity and higher BMI to a greater risk of infection.

These study findings also highlight the importance of vaccinating children to protect both the children and vulnerable members of their household. Their higher rate of asymptomatic infection, high viral loads, and close physical interactions with other household members may make children more efficient SARS-CoV-2 transmitters.

Where can I go to learn more?

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

• NIH news release explaining the results of this study.

COVID-19: Human Epidemiology and Response to SARS-CoV-2 (HEROS)

• Information on the purpose and detailed description of the HEROS study.

Long-Term Study of Children with COVID-19 Begins

• This study, which tracks the effects of COVID-19 on children’s physical and mental health over three years, is part of the Researching COVID to Enhance Recovery (RECOVER) Initiative to understand, prevent, and treat long-term effects related to COVID-19.

Sources

Seibold, M. A., Moore, C. M., Everman, J. L., Williams, B. J. M., Nolin, J. D., Fairbanks-Mahnke, A., Plender, E. G., Patel, B. B., Arbes, S. J., Bacharier, L. B., Bendixsen, C. G., Calatroni, A., Camargo Jr., C. A., Dupont, W. D., Furuta, G. T., Gebretsadik, T., Gruchalla, R. S., Gupta, R. S., Khurana Hershey, G. K., Murrison, L. B., . . . & Hartert, T. V. (2022). Risk factors for SARS-CoV-2 infection and transmission in households with children with asthma and allergy: A prospective surveillance study. Journal of Allergy and Clinical Immunology. https://doi.org/10.1016/j.jaci.2022.05.014