What cold weather means for COVID-19

Across the U.S., temperatures are dropping while COVID-19 cases are rising. According to Johns Hopkins University, all 50 states are seeing growing numbers of cases and the seven-day average for new coronavirus infections is 3.5 times higher than it was in September. Hospitalizations and deaths in many cities are also mounting.

The question is: Does the cold weather cause the increase in infections, or is our response to the chill the real culprit?

According to research from the University of Texas at Austin, temperature and humidity do not significantly affect how the coronavirus spreads. However, what does have an effect is how we behave in reaction to the weather. In a comparison of factors that led to infection, weather contributed less than 3% to the outcome, while taking trips contributed 34%, and time away from home contributed 26%. The population and density of communities also played significant roles.

“We heard a lot of people say that the virus would go away during the summertime, and clearly that was not the case,” says Dr. Abisola Olulade, a family medicine doctor with Sharp Rees-Stealy Medical Group. “This is a novel virus that continues to defy expectations. Temperature changes have not stopped the spread of the virus, which is why we need to continue to take distancing, hand-washing and mask wearing very seriously.”

Why winter weather will likely lead to increased infections
Dr. Olulade points out that when it's colder, people spend more time indoors — even in San Diego, where temperatures are far milder than other areas of the country. And the holidays lead to increased numbers of people traveling. These combined dynamics lead to greater congregation and increased spread of the virus.

“We must realize that although the virus is invisible, it hasn't gone away,” Dr. Olulade says. “Going into the holidays and winter season, there are so many factors that are converging that may make this one of the most challenging times of the pandemic.”

Dr. Olulade joins the nation’s COVID-19 experts in warning that if we let down our guard due to pandemic fatigue or a desire to spend time with loved ones in person, or fail to take prevention measures seriously, the virus will continue to spread. “We will continue to see increased case counts along with what is no longer a hypothetical in other states: an overwhelmed health care system,” she says.

What you can do to stop the spread
Acknowledging that small household gatherings have become an important contributor to rising COVID-19 infections across the U.S., the Centers for Disease Control and Prevention (CDC) is advising people to celebrate the holidays virtually or only with members of their own household to lower the risk for spreading the disease. California, Oregon and Washington recently issued a joint travel advisory urging against nonessential, out-of-state travel and asking visitors entering the states or returning home from travel to self-quarantine to slow the spread of the virus.

If you do decide to gather with loved ones, the CDC reports the size of any gathering should be determined based on the ability of attendees from different households to stay 6 feet apart, wear facial coverings, wash hands and follow all local safety guidance.

Other factors to consider:

• Levels of COVID-19 cases in the location of the gathering

• Possible exposure to COVID-19 during travel

• Duration of the gathering

• Number of people at the gathering (follow local guidance on limits)

• Behaviors of attendees in the two weeks prior to the gathering

• Behaviors of attendees during the gathering

“The virus doesn't care whether or not you're tired of it,” Dr. Olulade says. “It's still here and will continue to run rampant through our community if we let it. This is just one holiday season and there's a lot of hope that by next year we will have vaccines and even better treatments, so let’s stay strong and continue our efforts to prevent the spread of the coronavirus.”