Impact of the COVID-19 Pandemic on Allergy Indicators in Adults: A Retrospective Study from 2018 to 2023

This study aimed to assess the impact of the COVID-19 pandemic on allergy indicators in adult patients. We analyzed 8015 tIgE and 34,163 allergen detection results from 2018 to 2023. Patients were categorized into pre-pandemic (2018-2019), pandemic-period (2020-2022), and post-pandemic (2023) groups. Group comparisons and logistic regression analyses examined the relationship between relevant factors and tIgE positivity rates. Inverse probability of treatment weighting (IPTW) using propensity scores was applied to address baseline imbalances. The findings demonstrated consistent conclusions for both tIgE and allergen detection. The tIgE positivity rates and levels were significantly lower during and after the pandemic compared to the pre-pandemic period. Univariate and multivariate logistic regression analyses revealed that the pandemic and post-pandemic periods were associated with a reduced risk of tIgE positivity, with the pandemic period exhibiting a more pronounced effect. After IPTW adjustment, for tIgE, the pandemic and post-pandemic periods were associated with reduced tIgE positivity (OR = 0.436 and 0.465, respectively; P < 0.001). For tIgE related to allergen detection, the pandemic and post-pandemic periods were associated with reduced tIgE positivity (OR = 0.733 and 0.817, respectively; P < 0.001). Additionally, allergen detection results indicated that indoor inhaled allergens, such as cat and dog hair dander, had increased positivity rates, while outdoor allergens such as Artemisia argyi and ragweed showed decreased positivity rates. The COVID-19 pandemic significantly improved allergy indicators among adults, likely due to lifestyle changes such as increased mask-wearing and reduced outdoor activities.