The Conversation
You’ve probably heard that “Don’t go out in winter with wet hair or without a coat, because you’ll catch a cold.”
But those claims are not entirely true. As with many things, the reality is more complicated. Here’s the difference: cold is not the reason you get a cold, although it is true that cold weather makes it easier to spread respiratory viruses like the cold and flu.
Research also shows that lower temperatures are associated with higher rates of COVID-19.
Added to this trend is the concern of experts about vaccination rates in children in the United States. The Centers for Disease Control and Prevention (CDC) reported Wednesday that as of Nov. 30, just over a third of American children (37%) had received the flu vaccine, less than the 43% from last year at the same time, NBC News reported.
The downward trend worries pediatricians, who are beginning to see an increase in flu cases.
As a nursing professor with a background in public health, I am often asked about the spread of infectious diseases, including the relationship between cold and cold. We explain what really happens.
Many viruses, including rhinovirus (the common culprit of the common cold), influenza, and SARS-CoV-2, the virus that causes COVID-19, remain infectious longer and replicate faster in colder temperatures and with lower humidity levels. This, along with the fact that people are spending more time indoors and in close contact with others during cold weather, are common reasons why germs are more likely to spread.
Influenza and respiratory syncytial virus, or RSV, tend to have a definite seasonality in the fall and winter. However, due to the emergence of new COVID-19 variants and waning immunity from previous infections and vaccines over time, COVID-19 is not your typical cold-weather respiratory virus. As an example, COVID-19 infection rates have increased every summer since 2020.
Virus transmission is easier when it is cold
More specifically, cold weather can change the outer membrane of the flu virus, making it more solid and rubbery. Scientists believe the rubbery layer makes it easier for the virus to spread between people.
Cold winter air isn’t the only thing that causes problems. Dry air, in addition to being cold, has been linked to flu outbreaks. This is because dry winter air helps the flu virus remain infectious for longer. Dry air, which is common in winter, causes water in respiratory droplets to evaporate more quickly. This results in smaller particles, which can last longer and travel farther after coughing or sneezing.
The immune system response during the cold is also very important. Inhaling cold air can negatively affect the immune response in the respiratory tract, making it easier for viruses to appear. That’s why wearing a scarf over your nose and mouth can help prevent a cold by warming the air you inhale.
Additionally, most people receive less sunlight in winter. This is a problem because the sun is a major source of vitamin D, which is essential for a healthy immune system. Physical activity, another factor, also tends to decrease during the winter. People are three times more likely to delay exercising in snowy or icy conditions.
Additionally, people are spending more time indoors. That usually means closer contact with other people, which leads to the spread of disease. Respiratory viruses usually spread within 6 feet (1.8 meters) of an infected person.
Added to this is that cold temperatures and low humidity dry out the eyes and the mucous membranes of the nose and throat. Because viruses that cause colds, flu, and COVID-19 are typically inhaled, the virus can attach more easily to these damaged, dry ducts.
What you can do
The bottom line is that being wet and cold does not make you sick. That being said, there are strategies to help prevent illness year-round:
- Avoid touching your face, something people do between nine and 23 times an hour.
- Stay hydrated. Eight glasses of water a day is a good goal, but it could be more or less depending on the person’s lifestyle and size.
- Eat a well-balanced diet. Dark leafy greens are rich in immune-boosting vitamins, while eggs, fortified milk, salmon, and tuna have vitamin D.
- Stay physically active, even during the winter.
- Get enough sleep.
- Frequently clean hard, high-touch surfaces in your home.
- If your nose or throat gets dry in winter, consider using a humidifier.
- Get vaccinated annually against flu and COVID-19.
By following these tips, you can ensure you have a healthy winter season.
