The advice from grandmothers about catching a cold from walking barefoot on a cold floor or stepping outside with wet hair has some validity.

Cold weather, particularly in the winter, does not directly cause the common cold. However, it can impair your immune function, and the chillier, drier atmosphere can promote the activity of respiratory viruses.

“That’s not just an old wives’ tale,” stated Dr. Winston Rajendram, a family medicine doctor associated with Northwestern Medicine in the Chicago area, in an interview with YSL News.

Additionally, crowded gatherings during the holidays can act as major spreading events for viruses.

“In lower temperatures, these viruses are more prevalent,” he explained. “Consequently, the likelihood of contracting a virus increases when it’s colder.”

Why are viruses more prevalent?

Viruses need a host to reproduce, and they can only survive outside for a limited time.

When individuals who are infected with a cold or COVID-19 cough or sneeze, they release respiratory droplets containing the virus, according to Andrew Pekosz, a scholar in molecular biology and immunology at Johns Hopkins Bloomberg School of Public Health. In cooler, drier air, these droplets linger in the atmosphere longer, elevating the risk of transmission to those nearby. This can be exacerbated by air conditioning, which lowers humidity levels.

“This significantly extends the period during which you might become infected, whether by entering a space or touching a surface that has just been contaminated with these viruses,” Pekosz noted.

In warmer, more humid conditions, viruses struggle to survive outside a host for long. Studies indicate that flu viruses in high humidity can attach to water particles and subsequently drop out of the air, reducing the time they remain airborne.

Pekosz emphasized that while people can contract flu and COVID-19 at any time of year, including in tropical climates, transmission is facilitated by lower humidity levels.

“In essence, the conditions slightly shift in favor of the virus rather than our immunity,” he explained.

What about the sensation of being cold?

Cooler conditions can suppress the immune system, making our bodies more vulnerable to infections.

The human body is generally adept at managing drops in temperature, but the nose and upper airways may respond more sluggishly, according to Pekosz.

This sluggishness could clarify why these kinds of viruses tend to affect our respiratory system, as illustrated by a study examining immune responses in nasal cavity cells.

But we stay indoors during winter to escape the cold

In the frigid winter months, we often find ourselves indoors with larger groups. For instance, consider how office lunches in the summer differ from those in the winter.

Viruses have an easier time spreading indoors, where airflow is less optimal and air turnover in smaller rooms does not compare to that outdoors.

“Viruses can linger longer in these environments, and since we tend to stay there longer, it explains why we observe increased outbreaks of flu, SARS-CoV-2, and RSV during winter,” Pekosz noted.

How can we shield ourselves?

Rajendram advises discussing vaccine options with your healthcare provider during check-ups.

He recommends that everyone ages 6 months and older receive the flu vaccine. Last flu season, the U.S. recorded 470,000 flu-related hospital admissions and 28,000 deaths linked to flu complications, according to the Centers for Disease Control and Prevention. Vaccinations can mitigate the risk of severe infection.

The same applies to COVID-19, which now has an updated vaccine available for individuals 6 months and older, as well as for respiratory syncytial virus (RSV), with recommendations targeting older adults, pregnant women, and infants.

There is no vaccination for the common cold caused by rhinoviruses.

However, for all respiratory infections, it’s advisable to dress warmly with hats and gloves in cold weather.

Wearing a mask can also be beneficial. In some countries, wearing a mask signifies that an individual is unwell and is taking precautions for those around them, Rajendram explained. If feeling ill, it’s best to stay home to prevent spreading the illness to others.

It’s also wise to keep your hands away from your face. Pathogens can transfer from your mouth or nose to your hands, which may then contaminate someone else’s hand or a surface. When coughing or sneezing, aim to cover your mouth with your arm or use a tissue instead of your hand. Remember to wash your hands thoroughly and frequently with soap and water.