Impact of the COVID-19 Pandemic on Cockroach Allergy: A 4-Year Retrospective Study

Introduction: Sensitivity to indoor allergens increases the risks of asthma and the emergence of allergic diseases. Indoor allergens include house dust mite (HDM), pet dander, cockroach (CR), and molds. We investigated how CR sensitivity was affected during the pandemic period. Methods: This study included patients aged ≥18 years who visited the allergy unit of our clinic between March 2018 and March 2022 and who underwent skin prick tests (SPTs) for aeroallergens. Patients were divided into two groups: those of the prepandemic and pandemic periods, depending on the visit dates. Results: In all, 7,687 patients were recruited; 5,074 individuals with negative SPT results were excluded. Among the 2,613 atopic patients, CR sensitivity was detected in 278 (10.6%). The prevalence of CR sensitivity was significantly higher in the pandemic group than in the prepandemic group (12% vs. 8.6%; p < 0.05). The frequency of asthma was higher in patients with CR sensitivity than in others (33.1% vs. 26%, p = 0.011). In addition, individuals with CR sensitivity were older than others (p = 0.001). CR sensitivity was more common in males than in females (44.2% vs. 37.7%, p = 0.034). Moreover, dog and HDM sensitivities were more common in individuals with CR sensitivity than in others (p = 0.004, p < 0.001, respectively). Conclusion: This study reveals an increased sensitivity to CR during the pandemic and establishes an association between such sensitivity and the frequency of asthma. Variability in terms of CR sensitivity across different countries is emphasized. In addition, HDM and dog sensitivities were more common in individuals with CR sensitivity.