This essay is shared with permission from The Conversation, an online platform featuring the latest insights from research.

You may have been warned, “Never go outside in the winter with damp hair or without a jacket; you’ll surely catch a cold.”

This isn’t entirely accurate. The truth is a bit more complex. Simply being cold by itself doesn’t cause you to catch a cold. However, it’s true that cold climates can increase your chances of contracting respiratory viruses like the common cold or flu.

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Studies have also linked lower temperatures to higher rates of COVID-19 infections.

As a nursing professor with expertise in public health, I often field questions about the spread of infectious diseases, including the relationship between cold weather and the common cold. Let’s explore what really occurs.

Many viruses, such as the rhinovirus responsible for the common cold, influenza, and SARS-CoV-2—the virus that causes COVID-19—tend to survive longer and reproduce more rapidly in cold, dry conditions. This survival rate, combined with more indoor gatherings and closer human contact during colder months, facilitates the spread of viruses.

Both the flu and the respiratory syncytial virus (RSV) show a distinct pattern, peaking during the fall and winter. However, with emerging COVID-19 variants and waning immunity from past infections and vaccinations, COVID-19 does not adhere strictly to a cold-weather pattern. Notably, there have been spikes in COVID-19 cases each summer since 2020.

Cold Conditions Facilitate Virus Transmission

Specifically, colder temperatures can alter the outer membrane of the influenza virus, making it tougher and more resilient. This change is believed to ease the virus’s transmission from person to person.

It’s not just the cold that poses a problem, but also the dryness that accompanies it, which has been associated with flu outbreaks. The dry air of winter helps the influenza virus stay infectious for longer durations because it causes the moisture in respiratory droplets to evaporate quicker, allowing the smaller particles to linger in the air and travel further after someone coughs or sneezes.

Your immune system’s response in cold weather is also crucial. Breathing in cold air can compromise your respiratory tract’s immune response, making it easier for viruses to settle in. This is why covering your nose and mouth with a scarf can be beneficial—it warms the air you breathe in.

Additionally, people generally receive less sunlight in the winter months, which can be problematic since sunlight is a significant source of vitamin D, crucial for immune health. Physical activity also tends to decrease during this time, with people being three times more likely to skip exercising in snowy or icy conditions.

People also tend to spend more time indoors during the winter, often in closer proximity to others, which facilitates the spread of respiratory viruses. These viruses usually spread within a 6-foot radius of an infected person.

Moreover, cold temperatures and low humidity can dry out the eyes and mucous membranes in your nose and throat. Since viruses that cause colds, the flu, and COVID-19 are typically inhaled, a virus can more easily attach to these dried-out membranes.

How to Stay Healthy

Ultimately, being cold and wet doesn’t make you sick. However, there are several strategies to help prevent illness throughout the year:

• Wash your hands frequently.

• Avoid touching your face, which happens often—up to 23 times per hour.

• Keep hydrated. Aim for about eight glasses of water a day, although this can vary based on your lifestyle and body size.

• Eat a balanced diet. Include plenty of dark green, leafy vegetables, which are full of vitamins that support the immune system, and foods like eggs, fortified milk, salmon, and tuna, which are good sources of vitamin D.

• Maintain physical activity, even in the winter.

• Ensure you get enough sleep.

• Regularly clean frequently touched hard surfaces in your home.

• If your nose or throat feels dry during the winter, consider using a humidifier.

• Stay up to date with your annual flu and COVID-19 vaccinations.

Following these tips can help ensure you stay healthy during the winter months.

This article was initially published on The Conversation. Read the original article.