Flu shot: Your best bet for avoiding influenza
Getting a flu shot often protects you from coming down with the flu. And although the flu shot doesn't always provide total protection, it's worth getting.
This year's annual flu shot will offer protection against three or four of the influenza viruses expected to be in circulation this flu season. A high-dose flu vaccine as well as an additional vaccine also will be available for adults age 65 and older.
Influenza is a respiratory infection that can cause serious complications, particularly in young children, older adults and people with certain medical conditions. Getting an influenza vaccine — though not 100% effective — is the best way to prevent the misery of the flu and its complications. The Centers for Disease Control and Prevention (CDC) recommends annual flu vaccination for everyone age 6 months or older.
It takes up to two weeks to build immunity after a flu shot, but you can benefit from the vaccine even if you don't get it until after the flu season starts. It's usually best for people in the United States to get their flu vaccine in September and October, and aim to get it by the end of October. However, you can still protect yourself against late flu outbreaks if you get the vaccine in February or later.
Why do I need to get vaccinated every year?
Because flu viruses evolve so quickly, last year's vaccine may not protect you from this year's viruses. New flu vaccines are released every year to keep up with rapidly adapting flu viruses.
When you get vaccinated, your immune system produces antibodies to protect you from the viruses included in the vaccine. But antibody levels may decline over time — another reason to get a flu shot every year.
Who should get the flu vaccine?
The CDC recommends annual influenza vaccinations for everyone age 6 months or older. Vaccination is especially important for people at high risk of influenza complications, including:
- Pregnant women
- Older adults
- Young children
Children between 6 months and 8 years may need two doses of the flu vaccine, given at least four weeks apart, the first time they are given a flu vaccine. After that, they can receive single annual doses of the flu vaccine. A 2017 study showed that the vaccine significantly reduces a child's risk of dying of the flu. Check with your child's doctor.
Chronic medical conditions also can increase your risk of influenza complications. Examples include:
- Cancer or cancer treatment
- Chronic obstructive pulmonary disease (COPD)
- Cystic fibrosis
- Kidney or liver disease
Anyone with a chronic medical condition should get the flu vaccine.
Check with your doctor before receiving a flu vaccine if:
You're allergic to eggs. Most types of flu vaccines contain a small amount of egg protein. If you have a mild egg allergy — you only get hives from eating eggs, for example — you can receive the flu shot without any additional precautions. If you have a severe egg allergy, you may need to be vaccinated in a medical setting and be supervised by a doctor who is able to recognize and manage severe allergic reactions.
There are also flu vaccines that don't contain egg proteins, and are Food and Drug Administration (FDA) approved for use in people age 18 and older. Consult your doctor about your options.
- You had a severe reaction to a previous flu vaccine. The flu vaccine isn't recommended for anyone who had a severe reaction to a previous flu vaccine. Check with your doctor first, though. Some reactions might not be related to the vaccine.
Can the vaccine give me the flu or other respiratory diseases?
No. The flu vaccine can't give you the flu. It also does not increase your risk of COVID-19. But you might develop flu-like symptoms — despite getting a flu vaccine — for a variety of reasons, including:
- Reaction to the vaccine. Some people experience muscle aches and a fever for a day or two after receiving a flu vaccine. This may be a side effect of your body's production of protective antibodies.
- The two-week window. It takes about two weeks for the flu shot to take full effect. If you're exposed to the influenza virus shortly before or during that time period, you might catch the flu.
- Mismatched flu viruses. In some years, the influenza viruses used for the vaccine don't match the viruses circulating during the flu season. If this occurs, your flu shot will be less effective, but may still offer some protection.
- Other illnesses. Many other illnesses, such as the common cold, also produce flu-like symptoms. So you may think you have the flu when you actually don't.
Key points to remember
- Most people get better from the flu without problems, but the flu can be deadly. It can lead to serious health problems such as pneumonia, or it can make an existing disease worse. Every year, thousands of people end up in the hospital with other health problems from the flu.
- A flu vaccine may not always keep you from getting the seasonal flu, but it can make the symptoms milder and lower the risk of other health problems from the flu.
- A few people may not be able to get a flu vaccine. If you have a severe allergy to any part of the vaccine, have had a serious reaction to the vaccine in the past, had Guillain-Barré syndrome, or are ill, be sure to tell the person who gives the vaccine.
- The U.S. Centers for Disease Control and Prevention (CDC) recommends that everyone age 6 months and older should get a flu vaccine. But it's most important to get one if you're at high risk for other health problems from the flu. Those at high risk include young children, pregnant women, older adults, and people who have chronic diseases or weak immune systems.
- If you take care of someone who is at high risk, it's a good idea to get a flu vaccine. This can lower the chance that you could spread the flu to the person you care for.
- Flu viruses change quickly, so you need to get a flu vaccine every year.
- You can't get the flu from a flu vaccine.
If you become sick with the flu, you can also help prevent the spread of the flu by staying home and away from others. Continue staying home until your fever has been gone for at least 24 hours.
During the COVID-19 pandemic, both COVID-19 and the flu may be spreading at the same time. Your local health department and the CDC may suggest additional precautions to reduce your risk of COVID-19 or the flu, such as practicing social distancing and keeping 6 feet (2 meters) away from anyone outside your household. You also may need to wear a cloth face mask when in public, especially when it's hard to maintain distance.