The Association Between Food Allergy and Lower Risk of SARS-CoV-2 Infection


Food allergy is an immune system reaction that happens instantly after consuming a particular food. A small amount of an allergen-producing food might cause digestive issues, hives, or enlarged airways, as well as other indications and symptoms. Anaphylaxis, a reaction that can be life-threatening or even cause severe symptoms in particular persons with food allergies, can occur.

An allergy can significantly affect a person’s general quality of life. Depending on your allergies, you might not be able to enjoy everyday activities or feel your best. If even one family member has any allergy, families may feel a loss of normalcy that causes adjustments in decision-making and everyday routines. Many people might enjoy participating in school social activities, dining out, attending birthday parties, and celebrating Halloween. But those occasions can seem like minefields for families and people with food sensitivities. To protect their family or themselves, they must always be on guard.

However, the results of a recent study from the National Institutes of Health can make someone with allergies feel exceptionally lucky for having an allergy, probably for the first time in their life, despite the numerous disadvantages they encounter. The study found those with food allergies are less likely than those without them to contract SARS-CoV-2, the virus that causes COVID-19.

How Food Allergies Are Related to Lower Risk for COVID-19

More than 4,000 participants in approximately 1,400 homes with at least one person aged 21 or younger were monitored for SARS-CoV-2 infection by the HEROS study team. Before the extensive distribution of COVID-19 vaccines to non-healthcare workers in the United States and the overall development of variations of concern, this surveillance took place in 12 American cities between May 2020 and February 2021. Existing NIH-funded studies on allergy disorders were leveraged to source participants. About fifty percent of the children, teenagers, and adults who participated in the study reported having asthma, eczema, or allergic rhinitis.

Every two weeks, a caregiver in each household collected nose swabs from participants to test for SARS-CoV-2 and filled out weekly questionnaires. Additional nasal swabs were obtained if a household member displayed symptoms similar to COVID-19. Additionally, blood samples were taken regularly and, if necessary, following the first illness reported in a household.

Early results from other studies revealed that having an allergy condition would lessen a person’s vulnerability to SARS-CoV-2 infection when the HEROS study was initiated. The HEROS researchers found that having a self-reported, medically confirmed food allergy lowered the chance of infection by 50%. Still, asthma and the other allergic disorders tracked (eczema and allergic rhinitis) did not have a similar effect. The people who stated they had food allergies were allergic to three times as many allergens as the participants who did not.

The HEROS study team examined the levels of immunoglobulin E (IgE)-specific antibodies, which are essential in allergic disease, in blood taken from a sample of individuals because all of these symptoms were self-reported. The researchers found an agreement between self-reported food allergy and food allergen-specific IgE levels, supporting the reliability of self-reported food allergy among HEROS participants.

From their analysis, those with food allergies are less likely to contract SARS-CoV-2, the virus that causes COVID-19, than those without. Additionally, the new study has linked obesity and a high body mass index (BMI) to an elevated risk for SARS-CoV-2 infection. In contrast, earlier studies have linked obesity as a risk factor for severe COVID-19. Asthma did not, however, raise the likelihood of SARS-CoV-2 infection, according to the study.

According to the study, children under 12 have the same risk of contracting the virus as teenagers and adults, yet 75% of pediatric infections are asymptomatic. The study also confirmed a significant rate of SARS-CoV-2 transmission in households with children.

The scientists hypothesize that type 2 inflammation, a symptom of allergic diseases may lower the concentrations of the ACE2 receptor protein on the surface of airway cells. The inability of SARS-CoV-2 to infect cells may be hampered by the lack of this receptor, which the virus needs to enter cells. The decreased risk of infection for those who have food allergies may also be explained by variations in risk behaviors, such as a less frequent occurrence of eating out. The study team discovered that families with food-allergic individuals had just marginally lower community exposure levels than other households through biweekly assessments.

Additionally, it has been discovered that there is a significant, linear correlation between the chance of contracting SARS-CoV-2 and BMI, a measurement of body fat based on height and weight. The chance of infection increased by 9% for every 10 points in the BMI percentile. Overweight or obese participants had a 41% higher risk of infection than lean participants. To explain these findings, additional study is required. According to the researchers, planned investigations of gene expression in cells isolated from participant nasal swabs taken before and after SARS-CoV-2 infection may offer insights regarding the inflammatory milieu associated with infection, which may vary as BMI increases.

During the six-month surveillance period, there was also a 14% probability of SARS-CoV-2 infection in children, teenagers, and adults participating in the study. 75% of toddlers, 59% of teenagers, and 38% of adults had asymptomatic infections. SARS-CoV-2 was spread to multiple household members in 58% of the households where just one person contracted the disease.

The viral load, or the quantity of SARS-CoV-2 detected in nasal swabs, varied significantly among study participants across all age categories. The range of viral loads among infected kids was comparable to that of adults and teenagers. Compared to adults with high viral loads, a more significant percentage of infected children with high viral loads may be asymptomatic, given the prevalence of asymptomatic illness in children.

The HEROS researchers concluded that because of their high likelihood of asymptomatic infection, their possible high viral loads, and their close physical interactions with family members, young children might be particularly effective SARS-CoV-2 transmitters inside the home.

In sum, HEROS, the household surveillance study of SARS-CoV-2 infection and transmission in a population of kids and adults enriched for self-reported asthma and atopic conditions, offers some of the most substantial proof to date that asthma is not a potential risk for SARS-CoV-2 infection, symptoms, higher viral loads, or transmission events. Families with children have a higher risk of transmission because 75% of them are still asymptomatic.

Further research should be done on how participants with food allergies had a decreased chance of infection and transmission and whether having a higher BMI increases your risk of contracting SARS-CoV-2. The researchers also observed that finding new targets for infection prevention may result from studying the nature of the link between food allergy and BMI and the risk of SARS-CoV-2 infection.

Journal Reference

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, C. A., Dupont, W. D., Furuta, G. T., Gebretsadik, T., Gruchalla, R. S., Gupta, R. S., Khurana Hershey, G. K., … 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, 150(2), 302–311. 

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