Shifting patterns of allergen sensitization in 8,797 children with atopic dermatitis during the COVID-19 restriction measures: A retrospective study from Hangzhou, China

Objective: This study aimed to characterize the allergen among children with atopic dermatitis (AD) in Hangzhou, China, and to investigate the impact of COVID-19 restriction measures on these patterns. Methods: In this retrospective study of 8,797 children with AD, we analyzed specific immunoglobulin E (sIgE) results. We assessed sensitization prevalence, intensity, and used multivariable logistic regression to evaluate independent associations, including restriction phase (pre-, during-, post-), while adjusting for age, gender, and season. Results: The overall sensitization prevalence was 73.2%. House dust mite was the dominant sensitizer (45.6%), with the highest median sIgE level (19.05 IU/mL) and proportion of high-level sensitization (73.65%). Restriction measures were independently associated with a sharp decline in risk for most inhalant allergens during the restriction phase (OR=0.40, 95%CI:0.36-0.45), followed by significant post-restriction recovery (OR=0.81, 95%CI:0.73-0.90). In contrast, house dust mite sensitization risk increased post-restriction (OR=1.33, 95%CI:1.21-1.47). Food allergen sensitization showed a delayed, pronounced decline post-restriction (OR=0.49, 95%CI:0.44-0.54). Male gender and increasing age were confirmed as independent risk factors. Furthermore, distinct seasonal fluctuations were observed, with a higher risk of sensitization to various inhalant allergens during autumn and winter. Conclusion: The allergen sensitization profile in Hangzhou is distinct and heavily dominated by house dust mite. COVID-19 restriction measures were independently associated with divergent, allergen-specific shifts, highlighting the profound influence of environmental and behavioral factors. These findings advocate for dynamic, region-specific management and inform public health planning for allergic diseases.