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Will Warmer Weather Help Stop COVID-19?

Will Warmer Weather Help Stop COVID-19?

The novel coronavirus pandemic likely won’t fade away in summer with cold and flu season. Here’s why.

Updated May 22, 2020; 10am EST.

As the rate of new COVID-19 infections appears to be declining across many parts of the United States, you may be wondering if warmer weather is slowing the spread of disease. After all, the flu typically peaks between December and February, and then recedes during spring and summer. Colds tend to wane during summer months, as well. But is COVID-19 acting in a similar manner, fading away as the temperature rises?

What the experts say
In short—it may be, but perhaps not as much as we hoped.

Since the outbreak was only identified in China in December 2019, scientists are still working to understand how COVID-19 affects the body and how efficiently it spreads. And while some studies suggest that hot weather may play a role in reducing transmission, scientists caution that it’s likely not enough to control the pandemic entirely. From social distancing to population density, too many other factors can promote contagion.

In fact, it’s impossible to predict definitively whether COVID-19 will fade as summer progresses, according to an April 7 review of research published by the National Academies of Sciences, Engineering, and Medicine. And even if it does dwindle as time goes on, it likely won’t go away completely.

"It's a false hope to say, yes, that it will just disappear in the summertime like the influenza virus," Dr. Mike Ryan, Executive Director of the World Health Organization’s (WHO) Health Emergencies Program, told reporters on March 6. "We hope it does; that would be a godsend. But we can't make that assumption."

The role of weather
Here’s why many have speculated that weather may be a factor: The disease is a coronavirus, a type of virus known to have some seasonality, meaning it often comes and goes with certain seasons.

Like the flu, some of these illnesses spread more easily in winter months due to lower humidity and because people tend to congregate indoors, passing germs to one another—particularly in more crowded, poorly ventilated conditions.

In regions with warm summers and cold winters, coronavirus infections may tend to occur in the cooler months, but these infections can still happen at any time of the year.

There is a wide range of other variables that affect COVID-19’s spread aside from the weather, however. In addition to social distancing and population density, sunlight duration, human behavior, public health interventions and individual healthcare systems can also influence how quickly the disease is passed from person to person.

Once all these factors are considered, predicting COVID-19’s warm weather trajectory becomes a much more difficult task.

Isn’t it like other viruses, though?
Public health experts warn against assuming COVID-19 is just like the flu. Though both may have some seasonality, no one currently understands enough about the novel coronavirus to draw definite conclusions about similar behavior in warm weather. As far as experts know, humans have not built up immunity to COVID-19 as we have for the flu, which may affect transmission in summer.

Experts also caution against comparing COVID-19 to another pair of major illnesses linked to coronaviruses, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), since neither is considered to be seasonal.

The 2002-2003 SARS outbreak wasn’t slowed by warming weather. Rather, the damage was mitigated by intense public health interventions in affected countries, including China, Vietnam and Canada. And the 2012 MERS outbreak, which started in Saudi Arabia, never truly went away. More than 850 people have died of MERS in the years since it began, the WHO reports.

Tips to prevent the spread of COVID-19
Bottom line? Don’t expect hot weather to slow or stop COVID-19. Instead, help prevent infection with these tips from the CDC:

  • Wash your hands. Use soap and water and scrub for at least 20 seconds. If you don’t have access to soap and water, try hand sanitizer containing a minimum of 60 percent alcohol. Don’t touch your eyes, nose and mouth if you haven’t washed your hands.
     
  • Practice social distancing. Stay home as much as you can. When you have to visit a public place like a supermarket or drugstore, maintain a 6-foot distance from others and wear a non-medical cloth face covering over your nose and mouth, such as a mask or bandana.
     
  • Protect others. Remember that older people and those with chronic medical conditions, such as heart or lung disease and diabetes, are at a higher risk for severe disease or life-threatening complications. Cover your mouth with a clean tissue when you sneeze or cough. If you don’t have a tissue, use your upper sleeve or elbow—not your hands. Clean and disinfect dirty surfaces that people tend to touch, like doorknobs, phones and handles.

If you’ve been exposed to COVID-19, call your healthcare provider and take immediate steps to isolate yourself within your home. Many people are able to recover without going in for medical treatment.

Make sure to seek help right away if you experience emergency symptoms, including trouble breathing, chest pain, chest pressure, confusion and bluish lips or face. Call 911 and let the operator know you may have COVID-19.

Medically reviewed in March 2020.

Sources:

Centers for Disease Control and Prevention. “The Flu Season,” “Common Cold,” “Coronavirus Disease 19 (COVID-19): Frequently Asked Questions and Answers,” “Coronavirus Disease 19 (COVID-19): Steps to Prevent Illness,” “Coronavirus Disease 2019 (COVID-19): What to Do If You Are Sick,” “Coronavirus Disease 2019 (COVID-19): How to Protect Yourself and Others,” “Coronavirus Disease 2019 (COVID-19): Use of Cloth Face Coverings to Help Slow the Spread of COVID-19.”
James Gorman. “Summer Heat May Not Diminish Coronavirus Strength.” The New York Times. April 8, 2020.
National Academies of Sciences, Engineering, and Medicine. “Rapid Expert Consultation on SARS-CoV-2 Survival in Relation to Temperature and Humidity and Potential for Seasonality for the COVID-19 Pandemic”. April 7, 2020.
Maria Cheng and Victoria Milko. “Will heat stop the spread of new virus? No one really knows.” Associated Press. March 12, 2020.
World Health Organization. “Virtual Press Conference, 6 March 2020, on COVID-19 (Transcript),” “MERS Situation Update, November 2019.”
UptoDate.com. “Coronaviruses.”
Andrew Freedman and Jason Samenow. “Coronavirus may have a seasonal cycle, but that doesn’t mean it will go away this summer, experts warn.” The Washington Post. March 11, 2020.
Allison Aubrey. “Can Coronavirus Be Crushed By Warmer Weather?” NPR. February 12, 2020.
Sarah Gibbens. “Will warming spring temperatures slow the coronavirus outbreak?” NationalGeographic.com. March 6, 2020.
MM Sajadi, P Habibzadeh, et al. “Temperature and Latitude Analysis to Predict Potential Spread and Seasonality for COVID-19.” Social Science Research Network. March 10, 2020.
Ari Alstedter and John Lauerman. “Will Warm Weather Curb Coronavirus? What the Experts Say.” Bloomberg News. March 12, 2020.
Ted Regencia. “Will warmer weather slow the spread of coronavirus?” AlJazeera.com. March 11, 2020.
Berkeley Lovelace Jr. and Noah Higgins-Dunn. “WHO says coronavirus death rate is 3.4% globally, higher than previously thought.” CNBC.com. March 3, 2020.
Amy Gunia. “Will Warmer Weather Stop the Spread of the Coronavirus? Don't Count on It, Say Experts.” Time.com. February 28, 2020.

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