You’ve probably heard it before: “Don’t faint without blood, get pneumonia!For centuries, we’ve known that some infections, such as influenza, typically peak during the winter months in temperate climates. But why does this happen? A seasonality related to certain diseases, such as the flu, flu and Covid-19?Does venturing outdoors in colder temperatures actually make you more vulnerable to infection?Or is it simply because more people congregate indoors in freezing temperatures?The three most sensible reasons why you’re more likely to get the flu or flu during the winter months, as well as steps you can take to avoid those common infections.
It happens almost every winter: cracked skin, irritated eyes, and dry throat and nostrils. These common symptoms are due to low humidity, which is due to a reduced concentration of water in the cooler air. But dry skin and itchy eyes aren’t the only conceivable consequences of low humidity during the winter months. Low humidity also promotes virus transmission, in addition to influenza and SARS-CoV-2.
When a user with the flu or Covid-19 coughs or sneezes, the virus spreads in microscopic respiratory droplets. Under ideal conditions, i. e. , 40 to 50 percent relative humidity, those droplets are giant enough to usually fall to the ground or a surrounding surface within a radius of four to 6 feet. That’s why social distancing efforts can be very effective in reducing the rate of transmission of respiratory infections. But when the humidity point decreases, i. e. between 20 and 35% relative humidity, the length of the respiratory droplets decreases drastically. These smaller droplets can travel farther into the air, making it more likely that other people in the vicinity will be exposed.
Recent studies have shown that adding a humidifier to an indoor space, such as a classroom, can reduce the number of viruses on surfaces and the number of people infected in rooms without a humidifier. The take-home message: increase the amount of humidity in the air and reduce the distance that viruses can spread.
The human body has an incredible array of plant defenses that help prevent infection. In the upper respiratory tract, several plant barriers become less effective during the colder months. First, the respiratory epithelial cells in the nostrils are covered with cilia or fine hairs. -Type projections – which are regularly used to remove foreign bodies (e. g. , a virus or bacteria) from the respiratory tract. But cold, dry air can damage the respiratory epithelium, resulting in cilia that don’t work as well to remove foreign invaders.
Second, there is typically a thin layer of viscous fluid that lines the overhead lines and serves as a natural physical barrier to the respiratory epithelium. Think of it as a stream (i. e. , the layer of viscous liquid) flowing over a riverbed (i. e. , the respiratory epithelium). When the current flows normally, foreign elements, such as small branches or pebbles, cannot settle on it and damage the riverbed. Similarly, the layer of viscous fluid that lines the epithelial cells helps prevent infection and damage to those cells. But in the winter months, this thin layer of fluid can dry out, cutting through the protective barrier and expanding the chances of a virus infecting the underlying respiratory epithelium and subsequently causing disease.
Did you know that there are antibodies in your lines that help reduce infections? These antibodies, called immunoglobulin A (IgA), act as the first line of defense when we are exposed to a virus like the flu. But studies have shown that cold temperatures can cause an inhibition of IgA secretion, which can increase the likelihood of infection.
Winter not only brings cooler temperatures, but also darker days. Reduced sunlight and ultraviolet rays can have multiple effects on the spread of viruses. First, warmer temperatures and stronger UV light can inactivate some viruses, making viral pathogens more likely to persist. for longer periods during the colder, darker months. Second, sun exposure can lead to higher levels of vitamin D, which can intensify the innate immune response. As a result, more limited sun exposure during the winter can lead to vitamin D deficiency, which can negatively impact our ability to fight off an infection.
As we approach the winter months, take some steps to reduce your chances of becoming infected with a respiratory virus. First, keep indoor environments well-humidified and well-ventilated. Second, try to get out in the sun every day. Third, wear a mask if you are indoors in a public place. And finally, get vaccinated against influenza, RSV (if eligible), and Covid-19.