You’ve heard the phrase “flu season,” but you might be surprised to learn that flu season and respiratory infection season are different. It may also be surprising to know that researchers aren’t entirely sure why some sicknesses are seasonal, but only in some places.
At Apex Medical Center, our providers are experienced and know that we’re more likely to see patients with respiratory infections in the winter than at other times of the year, and more flu and rhinovirus infections during the spring and fall. Researchers have three main theories about why some viruses are seasonal.
Temperate climates tend to experience seasonal spikes in various viruses, including respiratory viruses, while tropical climates don’t. Generally speaking, the closer to the equator, the less seasonal variability there seems to be in viral infections.
This doesn’t hold true during pandemics. Scientists think this is because pandemic virus spread depends more on human behavior than anything else. Sometimes, when a pandemic virus becomes endemic, or common, it begins to follow seasonal patterns.
One of the main theories for the seasonality of respiratory virus infections has to do with the temperature and humidity, which change with the seasons. Viruses that are transmitted through aerosols, such as your breath, move differently depending on the size of the aerosols, which changes depending on evaporation.
In other words, when moisture evaporates faster, the aerosols are smaller and remain in the air for much longer. Heavier particles sink to the ground much faster and don’t travel as far through the air.
Some experiments have shown that viruses that are seasonal tend to be more stable and transmissible at lower temperatures.
Researchers have struggled to understand how human behavior impacts the seasonality of respiratory infections. That’s because human behavior is complex.
When it’s colder outside, people tend to stay indoors more, and that can make it easier for viruses to move from one person to another. Yet, in many places, people tend to spend most of their time inside, regardless of the temperature, so that’s not an entirely satisfactory explanation.
In the United States, people often travel during the holiday season, which occurs during the winter, and that could affect how respiratory viruses spread. Even though there’s generally more person-to-person contact during work weeks, the travel around the holidays could partially explain the seasonality of respiratory infections.
Interestingly, some studies have found that the innate response of the human immune system varies seasonally. Your body produces certain proteins, called cytokines, during the winter. Higher levels of specific cytokines are associated with higher mortality in some types of infections.
Relative humidity can also have an impact on how your immune system responds to certain viruses, as well.
Scientists and researchers are still working on understanding exactly why some viral infections follow seasonal patterns and will be for many years. So what does all of this mean for you?
In short, it means that you’re more likely to contract a respiratory infection during the winter. Everyone should take extra precautions to avoid getting sick in the winter, but especially people who are vulnerable to complications from respiratory infections, such as people who are:
If you, or someone in your household, falls into a higher risk category, consider scheduling an appointment at one of Apex Medical Center’s convenient locations to discuss appropriate precautions.
