Modifying Effect of Wind Speed on the Temperature-humidity Interaction Impacting Hand, Foot, and Mouth Disease as Assessed by Years Lived with Disability in Western China.

Objective: Hand, foot, and mouth disease (HFMD) transmission is sensitive to temperature-humidity interactions; however, the role of wind speed in modifying these effects remains unknown. This study investigated how wind speed modifies the combined effects of temperature and humidity on HFMD burden and identified subgroups of individuals with increased vulnerability to these climate exposures. Methods: distributed lag non-linear models. Additive interactions were assessed based on the proportions attributable to the interaction. The effects of sex, ethnicity, and urbanization were examined using stratified analyses. Results: Meteorological factors showed synergistic effects on HFMD burden. The peak burden occurred at moderate mean temperatures (8.7-22.8 °C) combined with high relative humidity (> 73.7%), showing a 2.4-fold increase versus the reference. High wind speed (> 2.5 m/s) further increased this effect, with a 3.1-fold increase in burden. This joint effect was attributable to the additive interaction involving wind speed and remained robust in stratified analyses that identified heightened vulnerability among boys, minority areas, and urban agglomerations. Conclusion: The HFMD burden was highest under specific combinations of temperature and humidity, and further increased with concurrent exposure to high wind speeds. Public health strategies for HFMD prevention should incorporate wind speed monitoring into early warning systems and address vulnerable subgroups, including boys and populations in minority areas and urban agglomerations.