Climate change is adversely affecting human health. Outbreaks and epidemics of climate-sensitive infectious diseases are of high public health concern, especially in lowerand middle-income countries that are highly vulnerable and exposed to climate change. As our understanding of linkages between climate and weather and infectious disease patterns improves, it may be possible to act earlier to prevent or minimize outbreaks and epidemics

Forecast-based financing (FbF) is a programme that enables access to humanitarian142,143 funding for early action, based on in-depth forecast information and risk analysis. The goal of FbF is to anticipate disasters, prevent their impact, if possible, and reduce human suffering and losses. Typically, FbF programmes have been designed to reduce or mitigate the impacts of hydrometeorological hazards such as floods, droughts, cyclones, heatwaves or cold waves. These have been formalized into more than 20 Early Action Protocols (EAPs) in different countries. Within these EAPs, early actions which aim to prevent or alleviate negative health outcomes, such as waterborne disease outbreaks, are quite common. For example, the cyclone EAP in Mozambique attempts to reduce the risk of diarrheal diseases due to damage to water infrastructure and resulting contamination. It does so by pre-emptively distributing chlorination tablets and buckets to families based on a trigger of forecasted wind speeds of 120 km/h or above at landfall. The lead time is 72 hours. Considerations for the impacts on the health sector have been integral to EAP development for hydrometeorological hazards. However, there is a new and growing interest in developing EAPs specifically for infectious disease outbreak risk, such as for dengue, malaria or cholera.

In the future, EAPs could be based on climate-informed disease risk prediction models. A prototype is the Barbados dengue early warning system144,145 developed in partnership with the Barbados Meteorological Services, Barbados Ministry of Health, French Red Cross, Red Cross Red Crescent Climate Centre and London School of Hygiene and Tropical Medicine. The climate-informed early warning model creates a probabilistic risk output of a dengue outbreak months in advance. If an above-average dengue transmission season is predicted several months in advance there is the opportunity to implement preventative public health action, such as vector control activities. Alternatively, EAPs could be developed with triggers linked to aggravating factors for disease outbreak risk in endemic areas, such as population displacement, weather or an increase in disease caseload. For example, the cholera EAP template developed by the International Federation of Red Cross and Red Crescent Societies aims to use early actions for earlier detection and response to cholera outbreaks in endemic countries.

The climate-informed early warning model creates a probabilistic risk output of a dengue outbreak months in advance.