You've likely heard the saying, “Don’t go outside in winter with damp hair or without a coat; you’ll catch a cold.” However, that isn't completely accurate. The reality is a bit more intricate. Here’s the clarification: Experiencing cold weather does not cause a cold. Nevertheless, it is true that chilly temperatures increase the likelihood of catching respiratory viruses like the cold and flu.
Studies indicate that lower temperatures correlate with higher rates of COVID-19 as well.
“As a nursing professor with a background in public health, I often receive inquiries about how infectious diseases spread, particularly regarding the connection between cold weather and catching a cold. Here’s an overview of what actually occurs,” explains Libby Richards from Purdue University.
Various viruses, such as rhinovirus – which is the usual source for the common cold – influenza, and SARS-CoV-2 (the virus responsible for COVID-19), remain viable for longer and replicate more quickly in cooler temperatures and lower humidity. This, combined with the fact that people spend more time indoors and in close proximity to others during colder months, is a primary reason that germs tend to spread more easily.
The flu and respiratory syncytial virus, or RSV, typically have a set seasonal pattern in fall and winter. However, due to the emergence of new COVID-19 variants and waning immunity from past infections and vaccinations, COVID-19 does not fit the profile of a standard cold-weather respiratory virus. For instance, COVID-19 infection rates have risen every summer since 2020.
Transmission of viruses is more effortless when temperatures drop.
Specifically, cold weather can alter the outer membrane of the influenza virus, making it sturdier and more elastic. Researchers believe this rubbery exterior facilitates the transfer of the virus from person to person.
It isn’t solely the frigid winter air that poses an issue. Dry air, in conjunction with cold, has been linked to flu outbreaks. This occurs because dry winter air significantly aids the influenza virus in remaining infectious for more extended periods. The lack of humidity in winter evaporates the moisture in respiratory droplets more rapidly, leading to smaller particles that can linger longer and travel farther after someone coughs or sneezes.
The immune system's response during cold weather is also quite significant. Breathing in cold air may negatively impact the immune response in the respiratory tract, making it easier for viruses to establish themselves. This is why covering your nose and mouth with a scarf may help prevent a cold, as it warms the inhaled air.
Moreover, most individuals receive less sunlight in winter. This is concerning because sunlight is a significant source of vitamin D, which is vital for maintaining a healthy immune system. Physical activity also tends to decline during winter. People are three times more likely to postpone exercising in snowy or icy conditions.
Instead, they often spend more time indoors, which generally leads to increased close interaction with others and, consequently, a higher risk of disease spread. Respiratory viruses typically transmit within a six-foot radius of an infected person.
Additionally, cold temperatures and low humidity can dry out your eyes and the mucous membranes in your nose and throat. Since the viruses responsible for colds, flu, and COVID-19 are often inhaled, they can attach more readily to these dehydrated passages.
What can you do:
In summary, being cold and wet does not directly lead to illness. However, there are numerous strategies you can implement to help prevent sickness throughout the year:
- Wash your hands frequently.
- Avoid touching your face, a habit people engage in between nine and 23 times an hour.
- Stay well-hydrated. Drinking eight glasses of water daily is a good target, though it may vary based on individual lifestyle and size.
- Consume a nutritious diet. Dark green, leafy vegetables are full of vitamins that support the immune system, while eggs, fortified milk, salmon, and tuna are good sources of vitamin D.
- Remain physically active, even in winter.
- Ensure you get enough sleep.
- Regularly clean hard, frequently touched surfaces in your home.
- If your nose or throat tends to dry out during winter, consider using a humidifier.
- Make sure to receive your annual flu and COVID-19 vaccines.
By following these guidelines, you can enjoy a healthier winter season.
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