Flu shots
Getting a flu shot each year helps protect you from influenza and lowers your risk of serious illness and hospitalization. Learn when to get vaccinated, who needs a flu vaccine, and how to schedule yours.
A flu shot helps lower your risk of getting influenza and developing serious complications. Even if you still get the flu after vaccination, the vaccine may help protect you from severe illness and hospitalization.
- Flu vaccination is recommended every year for everyone age 6 months and older, with rare exceptions. Some children ages 6 months through 8 years old need two doses, depending on their vaccination history.
- Adults age 65 and older have preferred vaccine options. High-dose, recombinant, or adjuvanted vaccines can help produce a stronger immune response. If these aren’t available, another age-appropriate flu vaccine can be given.
- September or October is the best time for most people to get vaccinated. Protection takes about two weeks to develop. Even if you miss the fall window, getting vaccinated during the winter months can help while flu is circulating.
- A flu shot cannot give you the flu. Mild side effects, such as a sore arm, headache, or body aches, usually go away within a few days. Having no side effects is also normal.
- Flu shots are recommended during pregnancy and can be given during any trimester. Vaccination helps protect the pregnant person and can also help protect their baby during the first months after birth.
- You can schedule your flu shot through UI Health Care. Your care team can help answer questions about vaccine options, timing, and how many doses your child needs.
The flu is a serious illness. Each year, it causes millions of illnesses in the United States and can lead to hospitalization and death. Even healthy people can get very sick and spread the virus to others.
“The flu isn’t just a bad cold,” says Nathan Shaw, MD, a family medicine physician at University of Iowa Health Care.
Vaccination is an important step in protecting yourself and the people around you.
What is the flu?
The flu is a contagious respiratory illness caused by influenza viruses. It is different from “stomach flu,” which refers to an intestinal illness that can cause diarrhea, cramps, nausea, and vomiting.
- Cough
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Headache
- Fatigue
Other respiratory viruses, including those that cause COVID-19 and RSV, can cause similar symptoms. Symptoms alone may not tell you which infection you have. Testing can sometimes help identify the cause and guide treatment decisions.
What are the benefits of a flu shot?
Getting a flu shot can:
- Lower your risk of getting the flu
- Reduce the severity of illness if you do get sick
- Lower your risk of flu-related hospitalization or death
- Help reduce the spread of flu in your community
A flu shot does not guarantee that you will avoid the flu or won’t miss work or school. But getting sick after vaccination does not mean the vaccine failed. It may still help protect you from more serious complications.
“It's important to have realistic expectations about the flu shot. We hope it keeps you from getting the flu altogether, but one of its most important benefits is reducing your risk of serious illness or hospitalization,” Shaw says.
A flu shot trains your immune system to recognize and respond to influenza viruses. Your body develops antibodies that help fight infection if you are exposed.
Flu viruses change over time, so vaccine composition is reviewed each year and updated to match the viruses expected to circulate. That is why you need a flu vaccine every year.
Researchers also continue to develop new approaches, including mRNA technology, with the goal of improving protection against flu. Your provider can help you choose an available vaccine appropriate for your age and health.
Who should get a flu shot?
Everyone ages 6 months and older should get a flu vaccine every year, with rare exceptions.
“We really want everybody to get a flu shot every year,” Shaw says.
Vaccination is especially important for people at higher risk of serious flu complications, including:
- Adults age 65 and older
- Young children
- Pregnant people
- People with chronic conditions, such as asthma, diabetes, or heart and lung disease
- People with weakened immune systems
Babies younger than 6 months old are too young to receive a flu vaccine. Vaccination is especially important for their caregivers and household members as well as health care workers and others who care for people at higher risk.
Most people need one dose each season. Some children ages 6 months through 8 years old need two doses, depending on their previous flu vaccinations. Your child’s provider can review their vaccination history and explain how many doses they need.
Do older adults need a different flu shot?
For adults age 65 and older, a high-dose, recombinant, or adjuvanted flu vaccine is preferred when available. These options are designed to produce a stronger immune response, which can help address changes in the immune system that happen with age.
An adjuvanted vaccine contains an ingredient that helps strengthen the body’s immune response. A recombinant vaccine uses a manufactured flu-virus protein.
If none of these preferred options is available when you get vaccinated, you can receive another flu vaccine approved for your age. Getting vaccinated is more important than delaying while searching for a particular option.
When should you get your flu vaccination?
For most people, September or October is the best time to get a flu vaccine, ideally before flu begins spreading widely. It takes about two weeks after vaccination for your body to develop protection.
Getting vaccinated too early, such as in July or August, may leave you with less protection later in the season, particularly if you are an older adult. Your provider can help you decide on timing if you may not have another opportunity to get vaccinated.
Children who need two doses should receive their first dose as soon as the vaccine becomes available so they can both doses, ideally by the end of October. The doses must be given at least four weeks apart.
If you miss the fall window, you can still benefit from vaccination while flu is circulating.
“As long as the flu is still circulating, it’s never too late to get the flu shot,” Shaw says.
Learn more about how to prepare for flu and respiratory virus season
Is the flu vaccine safe?
Flu vaccines have a strong safety record, supported by extensive research and ongoing safety monitoring. Most people can safely receive a flu vaccine, including people with an egg allergy.
Tell your provider before vaccination if you have had a severe allergic reaction to a previous flu vaccine or one of its ingredients. You should also discuss any history of Guillain-Barré syndrome, particularly if it developed within six weeks of a previous flu vaccine. Your provider can help determine which vaccine, if any, is appropriate for you.
Can a flu shot make me sick?
A flu shot cannot give you the flu. However, you may have temporary side effects, including:
- Soreness, redness, or swelling where you received the shot
- A low-grade fever
- Headache
- Muscle aches
- Tiredness
These symptoms can happen as your immune system responds to the vaccine. They are usually mild and go away within a few days.
Shaw explains that feeling a little under the weather afterward does not mean the vaccine caused an infection. It can be part of the immune response the vaccine is meant to create.
Having no side effects is also normal. You do not need to feel sick following the shot for the vaccine to work.
Can I get the flu shot if I’m pregnant?
Flu shots are recommended during pregnancy and can be given during any trimester. Pregnancy increases your risk of serious complications from the flu, making vaccination especially important.
Getting vaccinated helps protect you during pregnancy and can also help protect your baby during the first months after birth, before they are old enough to receive their own flu vaccine.
Pregnant patients should receive an injectable flu vaccine, rather than the nasal spray. Talk with your prenatal care provider about the best timing for you.