Health-informed early warning interventions for heat stress adaptation in a warming climate
1
School of Public Health, Peking University, Beijing, China
2
School of Engineering, The University of Hong Kong, Hong Kong, China
Popul. Med. 2026;8(Supplement Supplement 1):
ABSTRACT
BACKGROUND:
Extreme heat events are increasingly threatening global health. While heat-health warning systems have been adopted, substantial uncertainty remains regarding the effectiveness of different communication modalities and the added value of health-informed messaging beyond standard meteorological forecasts. Therefore, this study aimed to evaluate the effectiveness and cost-efficiency of different delivery channels for health-informed heat warnings in promoting protective behaviours and reducing heat-related morbidity.
METHODS:
We conducted a stepped-wedge cluster randomized trial in Ningbo, China. Five comparable communities were selected and randomly allocated to sequential implementation schedules for four intervention modalities and one without any interventions: WeChat messaging, text alerts, AI-powered voice calls, and digital displays. All interventions delivered identical health-informed content, including personalized risk assessments, symptom recognition guidance, and quantified protective recommendations, which were triggered when the temperature reached ≥35°C for ≥3 consecutive days. Primary outcomes were heat-protective behaviour scores (0-100 scale) assessed via questionnaires. Secondary outcomes comprised heat-related emergency department visits ascertained through health information systems linkage. We used mixed-effects models with random intercepts for community and individual, adjusting for calendar time and baseline covariates, and conducted a cost-effectiveness analysis to calculate the incremental cost per DALY averted.
RESULTS:
All intervention modalities significantly improved protective behaviours versus control periods, with significant heterogeneity by modality (p<0.05). Dose-response analyses revealed greater effects with longer exposure (6-8 weeks: 21.3 points vs. 2-4 weeks: 10.6 points; p-trend=0.003). Heat-related emergency visits declined 26% during intervention versus control periods, with larger reductions for WeChat and AI calls. WeChat achieved the most favorable cost-effectiveness. Combined WeChat-AI strategy showed super-additive effects with acceptable incremental cost-effectiveness.
CONCLUSIONS:
Governments must implement evidence-based, equity-oriented warning systems that translate forecasts into protective interventions to maximize preparedness and adaptation capability for the increasing heat stress challenge as health-informed heat warning systems can effectively reduce heat-related health burden.
Extreme heat events are increasingly threatening global health. While heat-health warning systems have been adopted, substantial uncertainty remains regarding the effectiveness of different communication modalities and the added value of health-informed messaging beyond standard meteorological forecasts. Therefore, this study aimed to evaluate the effectiveness and cost-efficiency of different delivery channels for health-informed heat warnings in promoting protective behaviours and reducing heat-related morbidity.
METHODS:
We conducted a stepped-wedge cluster randomized trial in Ningbo, China. Five comparable communities were selected and randomly allocated to sequential implementation schedules for four intervention modalities and one without any interventions: WeChat messaging, text alerts, AI-powered voice calls, and digital displays. All interventions delivered identical health-informed content, including personalized risk assessments, symptom recognition guidance, and quantified protective recommendations, which were triggered when the temperature reached ≥35°C for ≥3 consecutive days. Primary outcomes were heat-protective behaviour scores (0-100 scale) assessed via questionnaires. Secondary outcomes comprised heat-related emergency department visits ascertained through health information systems linkage. We used mixed-effects models with random intercepts for community and individual, adjusting for calendar time and baseline covariates, and conducted a cost-effectiveness analysis to calculate the incremental cost per DALY averted.
RESULTS:
All intervention modalities significantly improved protective behaviours versus control periods, with significant heterogeneity by modality (p<0.05). Dose-response analyses revealed greater effects with longer exposure (6-8 weeks: 21.3 points vs. 2-4 weeks: 10.6 points; p-trend=0.003). Heat-related emergency visits declined 26% during intervention versus control periods, with larger reductions for WeChat and AI calls. WeChat achieved the most favorable cost-effectiveness. Combined WeChat-AI strategy showed super-additive effects with acceptable incremental cost-effectiveness.
CONCLUSIONS:
Governments must implement evidence-based, equity-oriented warning systems that translate forecasts into protective interventions to maximize preparedness and adaptation capability for the increasing heat stress challenge as health-informed heat warning systems can effectively reduce heat-related health burden.
| eISSN: | 2654-1459 |
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