With most of the United States in the throes of wintry weather, a study emerged from Yale University that suggests people are more likely to catch a cold in chilly or frigid conditions.

Examining cells taken from the nasal cavities of mice, researchers found that when the body temperature inside the nose drops five degrees, the immune system does not work as well to fight the rhinovirus, or the common cold.

The virus reproduced more efficiently at the lower temperature, increasing the likelihood of developing a cold, says Yale professor of immunobiology and study author Akiko Iwasaki.

“In general, the lower the temperature, it seems the lower the innate immune response to viruses,” Iwasaki says.

Wearing a mask or warm scarf over the mouth and nose in chilly weather could help boost the immune response and keep a cold virus from taking hold. It also helps people with asthma to humidify and warm their breath; cold, dry air is an asthma trigger for some.

Researchers believe the findings could lead to more studies on how temperature affects the immune response in other illnesses, including asthma.

Cold and flu can worsen asthma, so if symptoms strike, patients should see a doctor to discuss any adjustments to their Asthma Action Plan. How to tell if it’s a cold or the flu? Knowing the difference could be critical if you have a chronic condition such as asthma or are at risk for bronchitis or pneumonia.