Does getting cold increase your chances of catching flu?

“Put your coat on or you’ll catch your death of cold.” It’s a common refrain that feeds the narrative that getting cold will make us sick. And it’s true that illnesses are more common during the winter months, but is it true that you are more likely to catch the flu if you forget your hat?

Not exactly. Writing in The Conversation, medical microbiologist Manal Mohammed from the University of Westminster has explained that colds and flu are caused by viruses that spread either by respiratory droplets or person to person regardless of the temperature. However, there is a bit of truth in the idea – many viruses survive for longer in colder and dryer conditions, increasing the chances of them hanging around and infecting a fresh victim. Cold weather also encourages us to spend more time indoors, and in crowded and poorly ventilated spaces viruses can build up and jump from person to person more easily. Reduced sunlight in winter also lowers production of Vitamin D, which can lead to a weakened immune system.

Understanding the link between cold weather and spread of viruses helps us better reduce risk of transmission, by improving indoor ventilation and humidity levels, and keeping our Vitamin D levels topped up. Public health messaging that drums home the message that viruses spread via contact and respiratory droplets are more effective than being nagged to wrap up warm.