The complexity of transmission of COVID-19 in the human population cannot be overstated. Although major transmission routes of COVID-19 remain as human-to-human interactions, understanding the possible role of climatic and weather processes in accelerating such interactions is still a challenge. The majority of studies on the transmission of this disease have suggested a positive association between a decrease in ambient air temperature and an increase in human cases. Using data from 19 early epicenters, we show that the relationship between the incidence of COVID-19 and temperature is a complex function of prevailing climatic conditions influencing human behavior that govern virus transmission dynamics. We note that under a dry (low-moisture) environment, notably at dew point temperatures below 0°C, the incidence of the disease was highest. Prevalence of the virus in the human population, when ambient air temperatures were higher than 24°C or lower than 17°C, was hypothesized to be a function of the interaction between humans and the built or ambient environment. An ambient air temperature range of 17 to 24°C was identified, within which virus transmission appears to decrease, leading to a reduction in COVID-19 human cases.

Climate shocks are causing increasingly severe damage and amplifying humanitarian needs. So far, humanitarian action has been mostly responsive, arriving after a crisis has materialized. With recent advances in forecasting, humanitarian and development organizations have been able to anticipate and respond ahead of crises. “Anticipatory action” (AA) seeks to ensure aid is provided before the peak impact of a shock occurs, reducing suffering and humanitarian needs. The UN Office for the Coordination of Humanitarian Affairs (OCHA) has been developing AA frameworks since 2019, coordinating collective AA and mobilizing finance. To date, these pilots have reached approximately 2.2 million people in Somalia, Ethiopia and Bangladesh. In six countries (Bangladesh, Burkina Faso, Malawi, Nepal, Niger, and The Philippines), frameworks are in place to reach a further 2.3 million people should the triggers be reached. OCHA is facilitating the design of AA plans in Chad, the Democratic Republic of the Congo (DRC), Madagascar, Mozambique and South Sudan. We share lessons from the pilots, focusing on three components: triggers, programming, and financing. We report that triggers must be sufficiently reliable to warrant action and funds disbursement. Forecasts are not available for all countries or hazards, and existing forecasts may not provide desired resolution or skill (accuracy) levels, especially at longer lead times. The timing of action therefore must balance forecast skill against operational needs. Funding is best when it is flexible and includes finance for framework design, evaluation and continued improvements. Finally we discuss the challenges and opportunities in scaling up AA.

Cholera remains a global public health threat in regions where social vulnerabilities intersect with climate and weather processes that impact infectious Vibrio cholerae. While access to safe drinking water and sanitation facilities limit cholera outbreaks, sheer cost of building such infrastructure limits the ability to safeguard the population. Here, using Yemen as an example where cholera outbreak was reported in 2016, we show how predictive abilities for forecasting risk, employing sociodemographical, microbiological, and climate information of cholera, can aid in combating disease outbreak. An epidemiological analysis using Bradford Hill Criteria was employed in near-real-time to understand a predictive model’s outputs and cholera cases in Yemen. We note that the model predicted cholera risk at least four weeks in advance for all governorates of Yemen with overall 72% accuracy (varies with the year). We argue the development of anticipatory decision-making frameworks for climate modulated diseases to design intervention activities and limit exposure of pathogens preemptively.