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Does transmission of COVID-19 slow down in the summer?

This article was published on
May 12, 2020

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COVID-19 can be spread in all climates and seasons. According to an August publication in the journal Nature, 'No human-settled area in the world is protected from COVID-19 transmission by virtue of weather, at any point in the year.' Studies that have explored the impact of temperature or weather on COVID-19 spread have shown mixed results. Some have been positive, some negative, and others neutral. Researchers have concluded that there are many factors that likely play a much larger role in the spread of the virus than the weather, including population density, human mobility, social distancing policies and practices, testing, public health facilities, and more. While more studies are needed, warmer weather does not appear to reduce the spread of COVID-19, and it does not impact how the virus spreads from person to person. Routine hand-washing, social distancing practices, avoidance of crowds, wearing face masks (the U.S. Centers for Disease Control and Prevention recommend wearing a cloth mask over a surgical mask), and surface cleaning should be used to prevent the spread of COVID-19 between people and via indirect (non-contact) transmission.

COVID-19 can be spread in all climates and seasons. According to an August publication in the journal Nature, 'No human-settled area in the world is protected from COVID-19 transmission by virtue of weather, at any point in the year.' Studies that have explored the impact of temperature or weather on COVID-19 spread have shown mixed results. Some have been positive, some negative, and others neutral. Researchers have concluded that there are many factors that likely play a much larger role in the spread of the virus than the weather, including population density, human mobility, social distancing policies and practices, testing, public health facilities, and more. While more studies are needed, warmer weather does not appear to reduce the spread of COVID-19, and it does not impact how the virus spreads from person to person. Routine hand-washing, social distancing practices, avoidance of crowds, wearing face masks (the U.S. Centers for Disease Control and Prevention recommend wearing a cloth mask over a surgical mask), and surface cleaning should be used to prevent the spread of COVID-19 between people and via indirect (non-contact) transmission.

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What our experts say

COVID-19 can be spread in all climates and seasons. According to an August publication in the journal Nature, 'No human-settled area in the world is protected from COVID-19 transmission by virtue of weather, at any point in the year.'

Studies that have explored the impact of temperature or weather on COVID-19 spread have shown mixed results. Some have been positive, some negative, and others neutral. Researchers have concluded that there are many factors that likely play a much larger role in the spread of the virus than the weather, including population density, human mobility, social distancing policies and practices, testing, public health facilities, and more.

While more studies are needed, warmer weather does not appear to reduce the spread of COVID-19, and it does not impact how the virus spreads from person to person. Routine hand-washing, social distancing practices, avoidance of crowds, wearing face masks (the U.S. Centers for Disease Control and Prevention recommend wearing a cloth mask over a surgical mask), and surface cleaning should be used to prevent the spread of COVID-19 between people and via indirect (non-contact) transmission.

Context and background

Some types of viruses (including some coronaviruses) have shown lower survival in warmer and more humid climates. Some lab experiments have shown that SARS-CoV-2 may be sensitive to temperature, humidity, and ultraviolet light. These lab tests may lead people to believe that climatic effects (e.g. warmer weather or seasonal changes) could slow the spread of the virus. Though more studies are needed, outside of the lab, the effect of climate (including temperature and humidity) on the spread of COVID-19 appears to be minimal. Countries around the world, including Asian and African countries with regular temperatures greater than 25 degrees celsius, have reported community transmission (spread) of the virus.

Resources

  1. Effective transmission across the globe: the role of climate in COVID-19 mitigation strategies (The Lancet)
  2. Misconceptions about weather and seasonality must not misguide COVID-19 response (Nature)
  3. No association of COVID-19 transmission with temperature or UV radiation in Chinese cities (European Respiratory Journal)
  4. Is the transmission of novel coronavirus disease (COVID-19) weather dependent? (Journal of the Air & Waste Management Association)
  5. Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021 (U.S. CDC)

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