An article by Baker and others published in Science July 2020 used climate-dependent epidemic modelling to simulate the SARS-CoV-2 pandemic by proving different scenarios based on known coronavirus biology.
Studies using a regression framework have found a role for temperature and relative and specific humidity in the transmission of SARS-CoV-2, suggesting that cold, dry conditions increase the transmission of the virus. However, with limited data on the current epidemic, these early stage results are inevitably inconclusive. Furthermore, the relative importance of climate drivers when compared with high population susceptibility during the pandemic stage of an emerging infection such as SARS-CoV-2 has not yet been fully characterised.
The authors found that although variations in weather may be important for endemic infections, during the pandemic stage of an emerging pathogen, the climate drives only modest changes to pandemic size. They suggested that non-pharmaceutical control measures indicate that they may moderate the pandemic-climate interaction through susceptible depletion.
Their findings suggested that without effective control measures, strong outbreaks are likely in more humid climates and summer weather will not substantially limit pandemic growth. They suggest that in terms of the SARS-CoV-2 pandemic, their results imply that both tropical and temperate locations should prepare for severe outbreaks of the disease and that summertime temperatures will not effectively limit the spread of the infection.
They conclude that this does not mean that the climate is not important in the longer term. Endemic cycles of the disease will likely be tied to climate factors, and seasonal peaks may vary with latitude. They continue that a more detailed understanding of climate drivers as well as immunity lengths will be crucial for understanding the implications of control measures. Furthermore, weather and near-term climate forecasts could be helpful for predicting secondary outbreaks after the initial pandemic phase has passed.
Dr Paul Ettlinger
The London General Practice