Transmission of the SARS-CoV-2 coronavirus depends on the season, but warm weather is not enough to curb transmission from one person to another. That’s the conclusion reached by specialists at Imperial College London, whose study was published in the journal Proceedings of the National Academy of Sciences.
The scientists showed that air temperature and population density are the main factors determining the speed at which the virus spreads in the absence of measures restricting mobility, such as social isolation. This means that lockdown and distancing cannot be abandoned just because of the onset of the summer season. At the same time, low temperatures during the fall and winter months contribute to an increased incidence of disease.
Environmental factors are known to affect infectious pathogens such as influenza viruses and other coronaviruses. For example, high temperatures and low humidity reduce the transmission of airborne droplets through the respiratory tract, preventing the spread of influenza. High temperatures also inactivate other coronaviruses in the air and on surfaces. For SARS-CoV-2, however, there has long been uncertainty.
Despite the hot climates of India, Brazil, and Iran, these countries have high incidence rates because population density has a greater influence on transmission than weather. During lockdown, when human contact is limited, the effect of temperature on transmission has been weak.