By Hayden McNeal, health & wellness reporter
As winter illnesses surge, a local epidemiologist claims that it is not the cold itself making people sick, but the crowding indoors and recycling of air that people often find themselves in during the winter months.
Many assume that dropping winter temperatures brings with it the flu season, increase in the common cold, and flare-ups in other health issues. With the high case rates of the influenza virus this past winter and sicknesses often flaring up during the colder months, questions arise about what role does cold weather actually play. During this time of year many other factors could be potential causes as well. From the large number of holidays with themes of coming together to celebrate, to the lack of outdoor areas for people to congregate during the colder months, the tight contact of the winter months could also be a factor. In addition to the rise of infectious diseases we see a rise of the effects of chronic diseases during this time.
Jason Deese, the District Epidemiologist with the New River Health District, sat down for an interview on Jan. 29 to explain how the cold winter weather actually affects the travel of infectious diseases and how the cold weather can trigger certain chronic diseases. And even though it is not his expertise, he was able to answer some questions on how the cold and winter weather can affect chronic diseases as well.
[Edited for Clarity]
How does cold weather affect the spread of illnesses like the flu or COVID-19?
It doesn’t necessarily directly affect it. It’s what we do in response to the cold air. So we’re sitting here in a closed space with limited air exchange, and when we breathe, talk, cough, sneeze, those droplets, or possibly aerosol particles concentrate in the air, and you’re more likely to end up breathing them in an infectious dose. That’s more or less how it happens.
There is some research out there about cool, dry air is maybe more efficient in carrying those particles so that they might remain suspended in the air for longer by outdoor air, the fact that it is cold air doesn’t make any difference. In fact, I’d say during covid, the best place you could be is outdoors in fresh air because when you are inside you are breathing concentrated droplets or aerosol.
Is it the cold itself or our winter behaviors that drive outbreaks?
The weather outside does not impact it directly. When you are indoors, your responsive cold air is to turn on heat, recycle the air to a certain degree so that we are losing heat. And you know, the most efficient model for keeping a place warm is basically to keep as much of that warm air trapped in the structure that you are in versus bringing in a whole bunch.
Does reduced sunlight and vitamin D impact immune function in winter?
Vitamin D does play a role in the body’s immune system, as many other nutritional components. Studies have shown, and I forget the exact percentage, people that live in North America during the winter do dip below what is considered optimal for vitamin D.
Are certain populations more vulnerable to winter-related infections?
In general, vulnerable would mean someone who’s got some type of issue with their immune system. The weaker immune systems tend to be in our older people. Additionally, very young people who haven’t established an immune system yet are vulnerable. People undergoing cancer therapy or therapy that suppresses the immune system, such as commercials on TV for Crohn’s disease or psoriasis, those are immune suppressing medications. Those types of things can make you a little bit more susceptible to various different types of infection. And that isn’t just necessarily during the winter, that will be at all times.
Here’s another example, the number one risk factor for bacterial meningitis infection is being a college freshman in a dormitory. Why do you think that is? Maybe not sanitary? What happens in the first few weeks of college. You’re interacting with a lot of new people. Maybe new study habits, burning the candle at both ends, partying at night, working in the day, wearing down your immune systems. Even people that start out perfectly healthy, can do things to themselves that can, you know, make them more susceptible to illness. Mono is another one that you know tends to spread in dorms with freshmen.
How does winter weather affect people with asthma and heart disease?
I’ll start out with heart disease, because when people go out in the cold, what happens? What happens to the blood vessels, they constrict and may lead to potential cardiac events? That’s fairly well established. In fact, when I was a kid, 12 or 13 years old, I saw a guy across the street shoveling his driveway and died of a heart attack. That’s actually fairly common. That plus doing activities that they’re not used to doing. If you did any shoveling snow in the last few days, it’s pretty vigorous activity. For some people, it is the first trip off the couch in a couple of weeks. It can put a lot of stress on the cardiovascular system.
There are many things that can precipitate asthma attacks in people, whether they be allergens, maybe dramatic changes in temperature. Some people stepping from a warm house and going and exercising out in the cold might precipitate asthma attacks. There’s potential there. It tends to be more likely in a cooler, drier environment.
Jason Deese in the Montgomery Health District Office conference room. Christiansburg, Va. Jan 29 2026. Deese did not want to take a picture in the area he actually worked due to the worry that someone’s medical information could accidentally be out.
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