The flu shot is one of the most common vaccines, yet it seems like every flu season, people still wonder: Does the flu shot actually protect against influenza? And is it really worth getting? Let’s break down the science, the benefits, and everything you need to know about the flu vaccine.
By the end of this article, you’ll have a better understanding of how it works, what’s in it, and why it’s a good idea to get it every year!
What Is the Flu Shot, and How Does It Work?
The flu shot is a vaccine that protects against the flu virus, also known as influenza. It’s given as an injection, typically in your arm, and works by stimulating your immune system to create a defense against the flu virus. But how exactly does this work?
When you get the flu vaccine, it introduces your body to small pieces of the flu virus—usually proteins found on the surface of the virus. These proteins are like the “wanted posters” for the virus, telling your immune system to recognize them if they ever show up in your body. This helps your body build immunity without actually making you sick. So, if you encounter the real flu virus later, your immune system is ready to fight it off quickly and efficiently.
Think of it like giving your body a cheat sheet before the test. You don’t get the flu, but your immune system learns what to look for so it can react faster if it sees the virus later.
The Science Behind the Flu Shot: Does It Really Protect You From Getting the Flu?
Yes! Real scientific evidence shows that the flu shot does protect against influenza, though it’s not 100% guaranteed to prevent you from getting sick. In fact, the Centers for Disease Control and Prevention (CDC) estimate that the flu vaccine reduces the risk of getting the flu by about 40-60% in a typical season.
While that might sound low, it’s important to note that even if you do get the flu after getting the vaccine, it’s likely to be a less severe case. Studies have shown that vaccinated individuals are less likely to experience complications from the flu, such as hospitalization or death.
But why doesn’t the flu vaccine work 100% of the time? The flu virus is constantly changing (mutating) through a process called “antigenic drift.” That means each year, the virus can look a little different from the previous year, which is why the flu shot has to be updated regularly to match the most common circulating strains. However, even if the virus mutates a little, the vaccine still provides important protection, especially against more severe cases.
How Is the Flu Vaccine Made?
Making the flu vaccine is no small task. It’s a complex process that takes place every year as scientists track which flu strains are most likely to be a threat. Here’s a breakdown of how the flu vaccine is made:
1. Identifying the Flu Strains
Every year, scientists around the world keep a close eye on the flu virus, collecting data from hospitals, labs, and even animal populations. The World Health Organization (WHO) helps determine which strains of the flu are likely to be the most widespread in the upcoming flu season. This is a tricky task, as the flu virus mutates quickly, but experts use the best data they have to predict what strains will be most common.
2. Growing the Virus
Once the strains are selected, scientists grow them in chicken eggs (yes, real eggs!) or in cell cultures in labs. This process takes time and is one of the most labor-intensive parts of vaccine production. The virus is then harvested from these eggs or cultures, and the proteins used in the vaccine are extracted.
3. Formulating the Vaccine
After the virus proteins are harvested, they are inactivated (killed) or weakened, so they can’t cause illness. These inactivated proteins are then mixed into the vaccine formula. Some flu vaccines contain “adjuvants,” which are substances added to enhance the immune response, making the vaccine more effective.
4. Testing and Distribution
Before the vaccine is ready to be used, it goes through rigorous testing to make sure it’s both safe and effective. After passing these tests, the vaccine is sent out to healthcare providers for distribution.
What Does the Flu Shot Contain?
The flu shot contains a mix of inactive or weakened flu virus proteins, and sometimes other ingredients like preservatives or adjuvants to improve the vaccine’s effectiveness. Here are the key components of the flu vaccine:
- Inactivated flu virus proteins: These are the pieces of the flu virus that train your immune system to recognize and fight the flu. They can’t cause the flu, but they prompt your body to create antibodies.
- Adjuvants: These are substances that help strengthen the immune response, making the vaccine more effective.
- Preservatives: In some vaccines, a preservative called thimerosal is used in multi-dose vials to prevent contamination. However, there are also thimerosal-free versions of the flu vaccine available.
- Stabilizers: These are added to keep the vaccine effective during storage and transport.
It’s important to note that the flu vaccine is updated every year, which is why you need to get a new shot each flu season. The ingredients change based on the strains of the flu that are predicted to circulate that year.
Is the Flu Shot Safe? Are There Any Risks?
In general, the flu shot is very safe. It’s been given to millions of people around the world, including children, pregnant women, and the elderly, and serious side effects are extremely rare. Most people only experience mild side effects, such as:
- Soreness or redness at the injection site
- Mild fever
- Fatigue or body aches for a day or two
These side effects are typically short-lived and are much less severe than actually getting the flu. In rare cases, some people might have an allergic reaction, but this is very uncommon. If you have concerns about allergies or other medical conditions, it’s always a good idea to talk to your doctor before getting the flu shot.
It’s also worth mentioning that the flu shot can’t give you the flu. This is a common misconception. Since the virus used in the vaccine is inactivated or weakened, it’s impossible for the vaccine to cause the flu. However, it’s still possible to catch the flu shortly after getting the vaccine, especially if you were already exposed to the virus before getting the shot.
Why Was Flu Type A So Bad This Year?
In the 2022-2023 flu season, the flu strain that caused the most problems was Influenza A (H3N2). This particular strain of the flu was much more aggressive than expected. It caused more severe illnesses and hospitalizations, especially in vulnerable populations like young children, the elderly, and people with weakened immune systems.
Several factors contributed to why this strain was so bad:
- Antigenic drift: As mentioned earlier, the flu virus constantly mutates. This year, the H3N2 strain had undergone changes that made it less recognizable to the immune system, even in people who had been vaccinated in previous years.
- Vaccine mismatch: While flu vaccines are updated annually to match the most common strains, sometimes the virus changes in ways that make the vaccine slightly less effective. This year’s vaccine wasn’t as well-matched to the H3N2 strain, meaning some people still got sick despite getting vaccinated.
- Weakened immunity: After a couple of years of relatively mild flu seasons (due to COVID-19 precautions and lockdowns), many people’s immune systems were less prepared to fight off the flu. This created a higher risk of infection and more severe cases.
Despite the challenges, getting the flu shot can still help reduce the severity of the so-called super flu and prevent complications. Even in years with a mismatch, the vaccine still provides protection.
Conclusion: The Flu Shot Is Worth It
In short, yes—the flu shot really does protect against influenza, and getting vaccinated is one of the best ways to prevent getting sick this flu season. While the flu vaccine isn’t perfect, it significantly reduces your chances of getting the flu and helps keep the illness less severe if you do get infected. Plus, it can protect others in your community, especially those who are most vulnerable to serious complications.
So, don’t skip the flu shot this year! It’s a simple, safe, and effective way to protect yourself and those around you from one of the most common—and sometimes dangerous—viruses out there. Stay healthy, and get that flu shot!
How does it protect others by getting the shot? We know for a fact that the covid shot didn’t protect either the person getting the shot or others from getting it, so how is the flu shot any different?
Hello Scott,
Thank you for your question.
The goal of vaccines isn’t always complete “infection blocking.” Vaccines generally work in two main ways:
Reduce your risk of infection (called sterilizing immunity), and/or
Reduce the severity and duration of illness, lowering how much virus you shed and how long you’re contagious.
Some vaccines — like measles or polio — stop infection almost completely. Others — like flu or COVID-19 — mostly reduce severe disease and transmission to a degree, but not entirely.