Despite generations of grandmotherly prodding, there isn't much in the way of conclusive evidence that cold weather can actually make us more likely to catch a cold. However, new research finally suggests Nana was onto something: chilly weather can make it easier for viruses to flourish.
In the study, published online this week in Proceedings of the National Academy of Sciences, researchers looked at the effects of temperature on a mouse version of the rhinovirus, often a cause of the common cold. Their results showed that when there was a slight chill — the air temperature was about seven degrees Fahrenheit lower than the mice's core body temp — the genes responsible for producing a virus-fighting protein were less active.
This suggests that cooler temperatures could lower our defences, making it easier for the virus to thrive. The study's authors say that this might allow the viruses to replicate faster — especially in our noses. This idea is consistent with research from the 1960s, which found that rhinoviruses were able to replicate more efficiently in cooler temperatures.
Obviously, you'd still need to come in contact with the germs before you can actually get sick; the weather itself won't make you ill. But, once the virus is there, breathing in colder air could exacerbate an already unpleasant situation. This week's forecast is a good reminder to practice good hand hygiene — and stock up on tissues just in case.