As the temperature drops, the familiar chorus of coughs and sniffles returns. But is braving the chilly air to blame for catching a cold? According to a leading vaccine expert, the link is more about our behaviour than the weather itself.
The Real Driver: Close Contact Indoors
Professor John Tregoning, an expert in vaccine immunology at Imperial College London, states that the seasonal spike in colds is "almost certainly correlation, not causation." While respiratory infections are more common in winter, the primary reason is that we spend more time indoors with others, often in poorly ventilated spaces.
He explains that different viruses peak at different times. "Rhinovirus spikes when kids return to school and spread germs around in small classrooms," says Tregoning, author of 'Live Forever? A Curious Scientist’s Guide to Wellness, Ageing and Death'. "RSV – another cold virus which is serious in elderly people and babies – peaks around new year."
What Role Does Cold Weather Play?
While behaviour is the main factor, cold temperatures can have a marginal effect. Sunlight contains UV light which can deactivate viruses, meaning droplets from a summer sneeze may be less infectious. Colder air can also slightly reduce the body's defensive capabilities, and some studies indicate rhinoviruses may replicate a little better in cooler conditions.
"If you were cold all the time, losing calories and exhausted, you’d be more prone to infection," Tregoning notes. However, the stark evidence from the Covid-19 pandemic lockdowns underscores the importance of contact: many common viruses declined dramatically when people stopped mixing, with one strain of flu even becoming extinct due to lack of spread.
The Most Effective Protection
So, what is the best defence against winter illness? Vaccination remains the most powerful tool for viruses like flu and RSV. "Vaccines don’t just prevent infection – they also have wider benefits, like reducing the risk of heart attacks," Professor Tregoning emphasises.
The key takeaway is clear: while wrapping up warm is sensible, the real risk lies in close, indoor contact during the colder months. Focusing on ventilation, hygiene, and recommended vaccinations offers a far stronger shield than simply avoiding the cold air outside.
