TOPLINE

The incidence of allergic diseases declined significantly during the first year of the COVID pandemic compared with the pre-pandemic year and most remained lower through year 3, with only anaphylaxis and food protein-induced enterocolitis syndrome (FPIES) returning to or exceeding pre-pandemic levels.

METHODOLOGY

• Researchers conducted a retrospective, repeated, monthly cross-sectional study to assess how the COVID pandemic may have affected the incidence of allergic diseases.
• More than 7 million beneficiaries of the US Military Health System (median age, 28.0-28.9 years; 47% female) were included to determine monthly incidence rates of allergic diseases diagnosed during the pre-pandemic year (March 2019-February 2020) through the first 3 years of the COVID pandemic.
• Allergic diseases were grouped into 12 categories: allergic rhinoconjunctivitis, asthma, medication allergy, atopic dermatitis, urticaria, food allergies, contact dermatitis, insect allergy, anaphylaxis, eosinophilic diseases, FPIES, and other allergy.
• A subanalysis assessed allergy diagnosis rates specifically in 3-year-olds, a group considered highly susceptible to changes in microbial exposure.

TAKEAWAY

• The incidence of any allergic diagnosis fell from 750 to 438 per 100,000 people between the pre-pandemic year and COVID year 1, with reductions observed across all 12 conditions.
• Compared with the pre-COVID year, the incident rates for development of any allergic disease were significantly lower in all 3 pandemic years, with incident rate ratios of 0.68, 0.66, and 0.61 in pandemic years 1, 2, and 3, respectively.
• Anaphylaxis and FPIES were the only conditions that did not remain lower than pre-pandemic levels in COVID years 2 and 3.
• In 3-year-olds, incidence of allergic rhinoconjunctivitis, atopic dermatitis, asthma, and urticaria all dropped significantly in year 1, with the mean monthly incident rates for asthma dropping from 213 to 74 per 100,000 3-year-olds between the pre-pandemic year and COVID year 1.

IN PRACTICE

"While reduced healthcare utilization may have initially contributed to some of the decline observed in incident rates of allergy, it appears likely that the decreased incidence rates of allergy diagnoses we observed in the MHS [Military Health System] during the first 3 years of the COVID-19 pandemic reflect a true decrease in the incidence of allergic diseases," the authors wrote.

SOURCE

John J. Brough, with the Walter Reed National Military Medical Center in Bethesda, Maryland, was the corresponding author of the study, which was published online on August 21 in Frontiers in Allergy.

LIMITATIONS

The study's retrospective design prevented the researchers from determining causation and limited their ability to directly account for potential confounders such as healthcare utilization. Reliance on codes for diagnoses may have resulted in misclassification due to coding errors. The use of a relatively short 1-year period to identify prior allergy diagnoses may have led to some recurrent diagnoses being misclassified as incident cases.

DISCLOSURES

This study was supported by funding from the Uniformed Services University of the Health Sciences, and the authors reported no commercial or financial relationships that could be considered potential conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.