The effects of the COVID-19 pandemic on allergen sensitivity of individuals.

Abstract

Introduction: The most common indoor allergens are house dust mites, molds, cockroaches, and pet allergens. Increasing exposure to these allergens increases the possibility of sensitization. This study examines changes in allergen sensitivity during the pre-pandemic, pandemic, and post-pandemic periods.

Methods: We retrospectively analyzed 19,525 skin prick test results from patients visiting the allergy clinic between January 2017 and August 2024. Patients were categorized into pre-pandemic (January 2017-March 2020), pandemic (March 2020-December 2022), and post-pandemic (January 2023-August 2024) periods. Allergen sensitization rates were compared across these timeframes.

Results: A linear increase was observed in cats-Dermatophagoides farinae, Dermatophagoides pteronyssinus, and Artemisia vulgaris allergen sensitization during and after the pandemic period compared to the pre-pandemic period (all p<0.001). Cockroach and grass-pollen sensitivities increased during the pandemic and remained elevated post-pandemic (all p<0.001). Dog allergen sensitivity peaked during the pandemic but declined post-pandemic (p<0.001). Sensitivity to the tree-pollen mixture, weed-pollen mixture, and Chenopodium album increased during the pandemic, slightly decreased post-pandemic, but remained significantly higher than pre-pandemic levels (p<0.001). In the test results studied since the pandemic period, Aspergillus fumigatus (p=0.007) and Cladosporium herbarum (p=0.005) allergen sensitivity was seen less in the post-pandemic period.

Conclusion: The current study reveals that the COVID-19 pandemic has significant effects on allergen sensitivity profiles along with changes in living habits. In particular, the increase in sensitivity to indoor allergens may be associated with the increased time spent at home during the pandemic, emphasizing the importance of environmental factors in the development of allergic diseases.