Flu season: the coldest part of the year that always has us questioning every sniffle, sneeze, and cough. For many, it also means getting a flu shot, and buying a few new tissue boxes. For the doctors at , it means answering the questions we’ve heard from our patients and equipping them with the information they need to keep themselves, their families, and their communities healthy.
So how worried should you be about getting the flu? Why should you get a flu shot? What even is the flu?
What is The Flu?
Influenza, more commonly known as simply “the flu,” is a contagious virus that affects the respiratory system, or the nose, throat, and lungs. The illness spreads from person to person via the tiny droplets the body produces when a person sneezes, coughs, or talks. These virus-containing droplets then infect other people either by landing directly in another person’s mouth or nose, or less commonly, by landing on a surface that is then touched by another person.
Typically, it takes about one to four days for someone exposed to and infected with the virus to show symptoms. Those with the flu are most contagious during the first three to four days after the illness begins, but some people, like young children and those with weakened immune systems, can be contagious for even longer. Also, it’s important to note that if a person has been infected, they can still pass the virus on before they start showing symptoms and know that they are ill.
Once sick, it might be easy to mistake the flu for a common cold. Both have symptoms like sneezing, coughing, and a sore throat, but the flu tends to come on much faster than a cold and be more intense. A person with the flu can experience moderate to severe illness, and in the worst cases, death. Other common symptoms of the flu include:
- Chills and sweats
- Muscle and body aches
- Shortness of breath
On top of these symptoms, children are more likely to experience vomiting and diarrhea if sick with the flu than adults. Children are also more likely to be infected than adults, with a person’s risk of infection decreasing as they age. Though we like to think of children as able to brush off illness, it is important to remember that children commonly need medical care if sick with the flu, including hospitalization, especially children under the age of 5.
Although adults over the age of 65 are at the lowest risk of catching the flu, they are more likely to be severely affected by it. Because the immune system becomes weaker as we age, older adults are more likely to be hospitalized or develop pneumonia during the course of their sickness, but the risk doesn’t stop there. During the first two weeks of infection, an older adult’s risk of heart attack more than triples, their risk of stroke doubles, and these risks stay elevated for several months.
Pregnant women, people with compromised immune systems, and people with chronic medical conditions such as asthma, diabetes, heart disease, or HIV/AIDS also have a high risk of developing serious flu-related complications. To put it simply, though many people think the flu isn’t a big deal, it is important to know that for many, it can be very dangerous, causing hundreds of thousands of hospitalizations every year.
If you believe you have the flu, it’s time to make an appointment with your , especially if you are at high risk of complications. Your doctor may give you a rapid test to help diagnose the flu, and if diagnosed, may prescribe antiviral medications. These medications shorten the length of your sickness, lessen the severity of your symptoms, and lessen the chance that you will need to be hospitalized.
Why Does “Flu Season” Happen During Colder Months?
In the northern hemisphere, the flu season typically begins between October and December, peaks in February, and ends in March, the coldest months of the year. However, it’s worth noting that the flu is present all year round; while it is more uncommon to catch during the summer months, it’s not impossible. But this pattern still begs the question: why does the flu seem to go hand-in-hand with the cold?
In the 1300s, the people of Italy suffered a flu epidemic that they referred to as influenza di freddo, or “influence of the cold.” It’s believed they thought the cold itself caused the illness, hence the name—viruses, after all, hadn’t been discovered yet, and they wouldn’t be until 1892. However, it’s understandable how the Italians came to the conclusion they did, given that modern studies have shown that the flu virus is most likely to thrive and infect in cold and dry climates. In other words, while cold weather does not cause the flu, the virus is more likely to spread in cold weather.
Our lifestyles also change in the winter in ways that may increase the spread of the flu. For instance, we are more likely to stay inside with the windows closed during the winter (for good reason!) making us more likely to breathe the same air as someone with the flu. Also, this tendency to stay indoors as well as the shorter days means that we see the sun less often, leading to lower levels of Vitamin D and melatonin, in turn weakening our immune system.
Why Should I Get a Flu Shot?
According to the CDC, around 3% to 11% of Americans get sick (and have symptoms) each year with the flu. That’s a pretty large range! This is due to the fact that each year, the flu mutates into a new strain, making it more or less severe and infectious. These mutations are also why you’re urged to get a vaccine to protect against the flu every year, more commonly referred to as a flu shot.
We’ve all heard a lot about vaccines over the past couple of years, as well as seen a rise in vaccine hesitancy, due to COVID-19, leading many to have questions about how vaccines work.
We get sick because of disease-causing organisms called pathogens; in the case of the flu, this pathogen is a virus. A pathogen has a subpart called an antigen that causes our body to create antibodies. These antibodies are often compared to soldiers—our very own frontline created naturally to fight that specific pathogen’s antigens. It takes time for these antibodies to be produced by our immune system after a pathogen enters our body, and in this time, we often become ill.
However, once the body knows how to create these antigen-specific antibodies, we are much less likely to become sick from the same pathogen again. To put it more simply, this is why people tend to only get chickenpox once; because the body created soldiers specifically to fight chickenpox, the next time that pathogen enters the body, those soldiers and the immune system respond immediately and already know how to protect us and defeat the pathogen before we get sick.
This is the same logic behind a vaccine. Typically, a vaccine utilizes the antigen alone, either by introducing it to the body without the pathogen, or with the help of more recent technology, by telling the body how to produce only the antigen. Either way, with the antigen in the body without the pathogen, the immune system creates antibodies and learns how to respond to the disease without the disease actually being present. Sometimes people do still feel ill after receiving a vaccine, but this is due to the immune system’s response, not because they have actually been infected.
The flu shot usually contains three weakened or inactivated strains of the flu that are predicted to be the dominant strains that season. These shots are typically updated two times a year because of how quickly the flu mutates, and ultimately cut a person’s risk of contracting the flu in half. Plus, for those who are vaccinated and still contract the flu, their immune system is more prepared to fight it, leading to shorter and more mild illnesses.
Vaccinated people are also less likely to pass the illness onto someone else. This leads to another term that’s been said a lot on the news the past few years: herd immunity. Because vaccinated people are less likely to contract or pass on the flu, the “herd,” or larger community, is safer. This is especially important for people who cannot get vaccinated, like infants under 6 months of age and those who are immunocompromised.
What Are the Differences Between the Flu and COVID-19?
Since March of 2020, the world has been living through a global pandemic. COVID-19 is a serious, contagious respiratory illness that has been said to have “flu-like symptoms,” and has also been dismissed as “just the flu.” This dismissal is misleading, as it downplays how dangerous both diseases can be, especially for people at high risk. Not only is the flu a serious and potentially lethal disease, but COVID-19 has proven to be even more so.
Saying that COVID-19 has “flu-like symptoms” however, is accurate. Many COVID-19 symptoms do overlap with those of the flu, including fever, chills, sweats, headaches, fatigue, cough, congestion, among others. These similar symptoms make testing crucial—if you think you may have the flu, you may actually have COVID-19 and should be tested. Also, it’s worth noting that COVID-19 can present with a symptom not associated with the flu: new loss of taste or smell. If you can’t smell your favorite candle or cup of coffee, or you can’t taste your favorite food, you may have COVID-19.
It’s also worth noting that, in comparison to years before, rates of the flu have been incredibly low. During the 2019 - 2020 season, the last flu season before the COVID-19 pandemic, (opens in a new tab) that there were:
- 39 million to 56 million instances of the flu
- 410,000 to 740,000 hospitalizations
- 24,000 to 62,000 adult deaths
- 195 pediatric deaths
Compare this to the 2020 - 2021 season:
- 1,675 instances of the flu
- 224 hospitalizations
- An unknown number of adult deaths (due to COVID-19)
- 1 pediatric death
This is likely due to several factors, including people with sickness being more likely to stay home and isolate, heavy mask usage by the general public including individuals who were sick and those who were not, and more people getting their flu shot. However, these numbers have risen again as these practices have declined, though not nearly to previous seasons’ numbers. For the first half of the 2021 - 2022 flu season, the (opens in a new tab), there have been:
- 1,200,000 to 2,100,000 instances of the flu
- 12,000 to 25,000 hospitalizations
- 730 to 2,200 deaths
There are two important takeaways we can get from this data. First, masking, isolating, and vaccinating all work together to better public health and lessen the severity and spread of diseases. Second, at this point in time, if you think you may have the flu, you need to be tested as it is more likely to be COVID-19.