Hay fever symptoms and preventive behavior during the COVID-19 pandemic and exploratory causal analysis: digital-based cohort study using AllerSearch smartphone application.

Abstract

Purpose :
Preventive measures for hay fever share commonalities with those for COVID-19. However, there are no formal reports on preventive behaviors or symptoms related to hay fever during the COVID-19 pandemic. To understand the impact of the pandemic on hay fever, we explored changes in hay fever symptoms and preventive behaviors during the pandemic using the AllerSearch® smartphone application, as well as their possible causal relationship.

Methods : The study was conducted using the AllerSearch® smartphone application for hay fever research. Users who agreed to participate in the study and indicated that they had hay fever were included in the study. We defined participants who answered during February 1st, 2018 to May 31st, 2019 as “pre-pandemic” subjects and those who answered during February 1st, 2020 to May 31, 2021 as “mid-pandemic” subjects. Hay fever symptoms and its preventive behaviors during both periods were compared. Symptoms were evaluated using the total hay fever symptom scores (TSS, range: 0-27), which assess for various nasal and non-nasal symptoms. Causal relationship between the pandemic and symptoms was examined using a statistical causal search method, the Linear Non-Gaussion Acyclic Model (LiNGAM).

Results : 3,199 pre-pandemic subjects and 1,339 mid-pandemic subjects were included in the analysis. Median (IQR) age was 34.0 and 54.3% were female. Mid-pandemic mask use rate was higher compared to pre-pandemic data, analyzed by logistic regression adjusted for age, sex, amount of pollen, and hay fever symptoms (Odds ratio: 1.238, 95% CI: 1.054-1.561). TSS was significantly worse mid-pandemic, shown by multiple regression adjusted by age, gender, amount of pollen, hours of sleep, number of walks, and preventive behaviors (regression coefficient: 1.047, 95% CI: 0.671-1.423). In addition, LiNGAM analysis suggested a causal effect of the pandemic on hay fever symptoms with a causal coefficient of 1.017.

Conclusions : Compared to pre-pandemic periods, mask-use rates increased mid-pandemic, which is thought to exert protective effects against developing hay fever symptoms. However, our data suggests a possible worsening of hay fever during the pandemic, supported by a causal relationship shown by our analysis. This data may warrant further investigation regarding the underpinnings of our counterintuitive results.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.