Multiple allergy differences before and after COVID-19
The proportion of people sensitized by allergens during COVID-19 increased noticeably compared with that before COVID-19, and the proportion of people with multiple sensitivities also increased considerably, with a statistical significance (X2=1621.815, P<0.05 , Table 4 ). Before COVID-19, 8.5% of patients were sensitized to one allergen, 5.7% to two allergens and 0.5% to three or more allergens. While 18% of patients were sensitized to one allergen, 12.8% to two allergens, 3.0% to three allergens, and 1.3% to four or more allergens during COVID-19. Additionally, explore the cross-allergy of five common allergens (Figure S2 ). Only 26.8% (16/596) and 12.0% (7/584) of the patients were sensitized to single d1 and d2, respectively. In other words, patients with d1 and d2 allergies were often sensitized to other allergens. A total of 610 patients with d1 and/or d2 sensitization were identified as dust mite sensitization. The most common co-sensitization was e2, with a rate of 15.9% (97/600), and dust mite as the most common allergen.