If you’ve noticed a strange lack of people in your classes, you can blame the season. Allergies, fevers, and the flu: all of these pesky ailments are extremely common right now during the winter months. What I find interesting is that scientists claim that this was a problem even centuries ago!

To understand the tie between the sickness today and its history, it’s important to look at the term “Influenza.” Originally (in Italian) called “Influenza di freddo” (meaning “influence of the sickness”), the flu already had acquired a cool nickname in the 1300s. During the 1300s and 1530s, the Earth was experiencing the beginning of “The Little Ice Age.” The Little Ice Age was a transitional period, leading our Earth into the colder, more seasonally structured place we know today. The Little Ice Age is why our Earth gets snow and is also the reason as to why the North and South Poles still exist. If not for this event, everything would feel a whole lot hotter around here!

The cold and dry air actually has an effect on our immune system and its response. An article released by CNN unpacking the research findings of Dr. Beier actually revealed that the drop in temperature can make you lose a lot of harmful  bacteria in the nostrils. In fact, Dr. Beier says that “[A] little bit of coldness in the tip of the nose was enough to take nearly 42% of the extracellular vesicles out of the fight.” Extracellular vesicles (AKA “EV”) can be thought of as messengers. These “messengers” allow our cells to communicate with other cells. What’s bad about losing these little messengers in our nose is that nearby immune cells will have no idea that they’re needed until you’ve already gotten sick. Basically, losing our EV will lessen our ability to defend ourselves from certain respiratory sicknesses, like the flu. 

What’s important to note about Dr. Beier’s test is that it was done in vitro. This means that the test was not done on a living organism. A test being done on a living organism would be called in vivo, like animal testing, (alive) human testing, and on plants. Since Dr. Beier’s research was done on dead human tissue, there is a chance that the EV died simply because of its detachment from a living and breathing human. You can never be 100% certain about research done in vitro, though it does obviously give us a good idea of what could really happen. 

Now, the big question: have humans always gotten the flu during winter? The data points to  yes. From the presence of the Little Ice Age to Dr. Beier’s findings, we can make the strong assumption that the human immune system has been pretty consistent over the centuries.