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Int J Infect Dis
. 2022 Nov 22;S1201-9712(22)00613-0.
doi: 10.1016/j.ijid.2022.11.023. Online ahead of print.
Indoor relative humidity shapes influenza seasonality in temperate and subtropical climates in China
Hao Lei 1 , Mengya Yang 2 , Zhaomin Dong 3 , Kejia Hu 2 , Tao Chen 4 , Lei Yang 4 , Nan Zhang 5 , Xiaoli Duan 6 , Shigui Yang 2 , Dayan Wang 4 , Yuelong Shu 7 , Yuguo Li 8
Affiliations
- PMID: 36427703
- DOI: 10.1016/j.ijid.2022.11.023
Abstract
Objective: The aim of this study was to explore whether indoor or outdoor relative humidity (RH) modulates the influenza epidemics transmission in temperate and subtropical climates.
Methods: In this study, daily temperature and RH in 1558 households from March 2017 to January 2019 in five cities across both temperate and subtropical regions in China were collected. City-level outdoor temperature and RH from 2013 to 2019 was collected from the weather stations. We first estimated the effective reproduction number (Rt) of influenza, and then used time-series analyses to explore the relationship between indoor/outdoor RH/absolute humidity (AH) and Rt of influenza. Furthermore, we expanded the measured one-year indoor temperature and RH data into five years, and used same method to examine the relationship between indoor/outdoor RH and Rt of influenza.
Results: Indoor RH displayed a seasonal pattern with highs during the summer months and lows during the winter months, while outdoor RH fluctuated with no consistent pattern in subtropical regions. Rt of influenza followed a U-shaped relationship with indoor RH in both temperate and subtropical regions, while U-shaped relationship was not observed between outdoor RH and Rt. In addition, indoor RH may be a better indicator for Rt of influenza than indoor AH.
Conclusion: The findings indicated that indoor RH may be the driver of influenza seasonality in both temperate and subtropical locations in China.
Keywords: China; Influenza; humidity; indoor; outdoor; seasonality.