The role of absolute humidity in influenza transmission in Beijing, China: risk assessment and attributable fraction identification

ABSTRACT

To assess the impact of absolute humidity on influenza transmission in Beijing from 2014 to 2019, we estimated the influenza transmissibility via the instantaneous reproduction number (R_t), and evaluated its nonlinear exposure-response association and delayed effects with absolute humidity by using the distributed lag nonlinear model (DLNM). Attributable fraction (AF) of R_t due to absolute humidity was calculated. The result showed a significant M-shaped relationship between R_t and absolute humidity. Compared with the effect of high absolute humidity, the low absolute humidity effect was more immediate with the most significant effect observed at lag 6 days. AFs were relatively high for the group aged 15–24 years, and was the lowest for the group aged 0–4 years with low absolute humidity. Therefore, we concluded that the component attributed to the low absolute humidity effect is greater. Young and middle-aged people are more sensitive to low absolute humidity than children and elderly.

KEYWORDS:

• Influenza transmission
• absolute humidity
• attributable risk
• exposure assessment
• infections

Acknowledgments

We are grateful to the staff members in district and municipal CDCs, and medical settings in Beijing for conducting field investigation, specimen collection, laboratory detection and case reporting.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contribution

Li Zhang: Writing – original draft, methodology. Chunna Ma: investigation. Wei Duan: investigation. Jie Yuan: methodology. Shuangsheng Wu: data curation. Ying Sun: data curation. Jiaojiao Zhang: editing. Jue Liu: supervision. Quanyi Wang: supervision, resources. Min Liu: conceptualization, project administration.

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.