Each fall, the flu descends like an unwelcome villain, sneaking through schools, offices and holiday gatherings, leaving fevers, aches and exhaustion in its wake.
Fortunately, you’ve got one shot to fight back — the flu shot.
Before you decide if you should get the flu shot or not, check out some common flu shot questions, including who should get it, what’s inside it and how it works.
Who should get a flu shot?
Protect yourself and your loved ones.
According to the Centers for Disease Control (CDC), almost everyone 6 months and older should get a flu shot to protect themselves and those around them each flu season.
Certain groups benefit even more from the flu shot, including children, seniors and people with chronic health conditions.
“The flu can be dangerous for anyone, but it’s especially risky for groups with weaker immune systems,” said Brian Curtis, MD, vice president, chief medical officer, OSF Medical Group. “Even if you’re healthy, getting your flu shot helps protect the most vulnerable people around you.”
If you’re pregnant, a flu shot protects both you and your baby by passing protective antibodies to your baby, so they are protected right at birth. Newborns and babies under 6 months can’t get a flu shot, so it’s also a good idea for parents, siblings, grandparents and anyone planning on coming into close contact with your child to consider getting the vaccine. This is called “cocooning” and helps keep your newborn safe by surrounding them with vaccinated people who are less likely to spread the flu.
Flu Shot Benefits
Like any vaccine, the flu shot has pros and cons, but for most people, the benefits far outweigh the disadvantages.
Benefits of the flu shot include:
- Reduces your chance of getting the flu
- Makes symptoms milder and recovery faster if you do get sick
- Lowers the risk of hospitalization and serious complications
Some people may experience mild side effects like soreness, fatigue or a low-grade fever. And since viruses can change each year, the flu vaccine may not prevent everyone from getting sick. Still, health experts agree that the protection it offers makes the flu shot one of the simplest, most effective tools we have against this virus.
“No matter your age or current health status, the flu can become serious quickly,” said Dr. Curtis. “So you really have to weigh the risks. A few hours of arm pain is nothing compared to the weeks of sickness the flu can bring. Or worse, a trip to the hospital.”
What’s in the flu vaccine?
Despite what some people may think, the flu shot does not contain a live virus. Instead, it uses an inactivated, or dead, version of the virus to train your immune system to recognize and fight off the flu without causing infection. To keep the vaccine safe and effective while it’s stored and transported, it also includes very small amounts of stabilizers and preservatives.
The flu shot is not an mRNA vaccine, which is a new type of vaccination that was used to create the COVID-19 vaccines. Both types of vaccines safely teach your immune system to recognize and fight the virus in different ways.
Most flu vaccines are made using eggs, but according to the CDC, people with egg allergies can still safely get a flu shot. If you’re worried, there are also egg-free options available. Be sure to talk with your provider about which option is best for you.
Flu Nasal Spray vs. Flu Shot
The main difference between the flu nasal spray and the traditional flu shot is that the nasal spray does use a live, but weakened, virus to stimulate your immune system. Like the flu shot, it can cause mild, short-lived side effects, but it does not give you the flu or make you sick.
The flu nasal spray is generally recommended for healthy people ages 2–49 who aren’t pregnant. Children under two, older adults and anyone with chronic health conditions should stick with the flu shot, which is safe and effective for nearly everyone.
“The nasal spray can be a good option for some kids or adults who are needle-averse,” said Dr. Curtis. “But overall, the flu shot is effective and works for the widest group of people.”
Best Time to Get a Flu Shot
The CDC recommends you get your flu shot before flu season peaks. Flu season is generally accepted as October through March, so the best time to get the flu shot is in September or October.
“Since it takes about two weeks to build full immunity, getting the flu shot early in the season gives your body time to be protected when flu season ramps up,” said Dr. Curtis.
Even if you miss the early window, it’s never too late to get a flu shot. Flu season may begin in the fall, but it can last into spring, so getting your flu shot anytime during the season is better than skipping it entirely.
Can you get a flu shot while sick?
If you have mild cold-like symptoms like a runny nose or sore throat, it’s generally safe to get the flu shot. However, if you are actively sick with a moderate or severe illness, especially with a fever, it’s best to wait until you’ve recovered. Getting the shot while your body is fighting a more serious illness can make side effects worse and may affect how well the vaccine works.
Flu Shot Effectiveness and Duration
Flu shot effectiveness can vary from year to year, depending on how well the vaccine matches current flu strains. Even if you do catch the flu, the vaccine is very effective at making your symptoms less severe, keeping you out of the hospital and helping you recover faster.
“Even in a year where the flu shot isn’t a perfect match, it still reduces severity and complications,” said Dr. Curtis. “That’s what keeps people out of the hospital.”
For most people, one flu shot per season is enough, and protection usually lasts through the height of flu season (October 1-March 31).
For children, seniors or people with weakened immune systems, talk with your doctor for more specific guidance on timing or extra doses.
Your Best Shot
Flu shots are safe, effective and one of the best ways to protect your family and community from the flu each season. While mild side effects can happen, the benefits far outweigh the risks, especially for those most vulnerable.
Last Updated: October 14, 2025