Susceptible supply limits the role of climate in the early SARS-CoV-2 pandemic

CORONAVIRUS In some quarters, it is hoped that increased humidity and higher temperatures over the Northern Hemisphere in the summer will snuff out the 2020 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. In reality, the situation is likely to be more complicated than that. Baker et al. used a climate-dependent epidemic model to simulate the SARS-CoV-2 pandemic, testing different scenarios of climate dependence based on known coronavirus biology. Levels of susceptibility among the population remain the driving factor for the pandemic, and without effective control measures, the pandemic will persist in the coming months, causing severe outbreaks even in humid climates. Summer will not substantially limit pandemic growth. Science this issue p. 315 A high proportion of susceptible people in a population is likely to outweigh any moderating effects of summer weather on virus transmission. Preliminary evidence suggests that climate may modulate the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Yet it remains unclear whether seasonal and geographic variations in climate can substantially alter the pandemic trajectory, given that high susceptibility is a core driver. Here, we use a climate-dependent epidemic model to simulate the SARS-CoV-2 pandemic by probing different scenarios based on known coronavirus biology. We find 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. A preliminary analysis of nonpharmaceutical control measures indicates that they may moderate the pandemic-climate interaction through susceptible depletion. Our findings suggest that without effective control measures, strong outbreaks are likely in more humid climates and summer weather will not substantially limit pandemic growth.