Patient education: Flu vaccine (The Basics)

What is the flu vaccine? — Vaccines can prevent certain serious or deadly infections. The flu vaccine can keep you from getting sick with the flu. Vaccines are also called "vaccinations" or "immunizations."

The flu is an infection that can cause fever, cough, body aches, and other symptoms. There are different forms of the flu, including the "seasonal" flu, the 2009-2010 pandemic H1N1 flu (also called the "swine" flu), and the bird flu (also called the "avian" flu). All forms of the flu are caused by viruses. The medical term for the flu is "influenza."

This article is about the flu vaccine that can protect you from the seasonal flu. The flu vaccines that are available now do not protect against bird flu.

Are there different forms of the flu vaccine? — Yes. The flu vaccine comes in different forms, including:

●A shot that goes into muscle (usually in the upper part of the arm)

●A nasal spray

Your doctor can help you decide which vaccine is best for you.

Who should get the flu vaccine and when? — All people age 6 months or older should get the flu vaccine every year. The vaccine is especially important for certain people at high risk (table 1).

The best time of year to get the flu vaccine is before the winter season begins. In the United States, it's best to get the vaccine by October. In southern countries, where winter happens in July and August, it's best to get the vaccine by May. No matter where you live, do your best to get the vaccine soon after it becomes available in your area. Depending on how many doses they have had in the past, children ages 6 months through 8 years might need 2 doses of the vaccine for it to work best.

Why should I get the flu vaccine? — Getting vaccinated can help keep you from getting sick. Plus, being vaccinated can help protect those around you from getting sick. If you have been vaccinated but get the flu, the vaccine can also keep you from getting severely ill or even dying.

Some years the flu vaccine is more effective than others. That's because the people developing the vaccines can't predict exactly how the flu virus is going to change year to year, and it takes months to make a new vaccine.

Some people think the flu vaccine doesn't work because they have known people who got the vaccine and got the flu anyway. But that does not mean the vaccine does not work. Many people who get sick after getting the flu vaccine do not actually have the flu; they have a cold caused by a virus unrelated to the flu virus, so the flu vaccine can't help with that.

Even in years when the vaccine is less effective, it still helps prevent some cases of the flu and also helps to prevent serious illness and outbreaks of the flu.

Can I get a flu vaccine and a COVID-19 vaccine at the same time? — Yes.

COVID-19 stands for "coronavirus disease 2019." It is caused by a virus called SARS-CoV-2. The virus first appeared in late 2019 and has since spread throughout the world.

In the United States, COVID-19 vaccines are available for people age 5 and older. It is important to get this vaccine as well as the flu vaccine. You can get both vaccines at the same time.

What side effects does the flu vaccine cause? — Often the vaccine causes no side effects. When it does cause side effects, it can cause:

●Redness, mild swelling, or soreness where you got the shot (if you got a shot)

●A mild fever

●A mild rash

●Headache or body aches

Vaccines also sometimes cause more serious side effects, such as severe allergic reactions. But serious side effects are rare.

Does the flu vaccine cause the flu? — No, the flu vaccine does not cause the flu. People sometimes feel sick after getting the vaccine. But this is often because they were already starting to get sick with the flu or another virus before they had the vaccine.

Does the flu vaccine cause autism? — No. After doing many careful studies, scientists have not found any link between vaccines and autism. Many years ago, a study reported a link between autism and vaccines. But that study turned out to be false. It has been withdrawn.

What if I am pregnant? — If you are pregnant, it is very important to get the flu vaccine. In pregnant people, flu symptoms can get worse quickly and be dangerous. The flu can even cause trouble breathing or lead to death of the pregnant person or their baby. That is why it is so important to get the flu vaccine if you are or will be pregnant during flu season.

What if I have an egg allergy? — People sometimes worry about this. That's because some forms of the flu vaccine contain small amounts of egg. But the amount is so small that it does not cause an allergic reaction. If you have an egg allergy, you should still get the flu vaccine.

What else can I do to prevent the flu? — In addition to getting the flu vaccine every year, you can:

●Wash your hands often with soap and water, or use alcohol hand rubs

●Stay away from people you know are sick

If you are exposed to the flu, antiviral medicines can help protect you from the flu, but those medicines are not appropriate for everyone. Also, antiviral medicines work only if you start them very soon after being exposed or as soon as you show symptoms.

To protect others, you should also:

●Stay home if you get the flu. Do not go to work or school until your fever has been gone for at least 24 hours, without taking fever-reducing medicine, such as Tylenol. If you work in a health care setting taking care of patients, you might need to stay home longer if you are still coughing.

●Cover your mouth and nose with the inside of your elbow when you cough or sneeze.

More on this topic

Patient education: Flu (The Basics)
Patient education: Vaccines and pregnancy (The Basics)
Patient education: Avoiding infections in pregnancy (The Basics)
Patient education: Cough, runny nose, and the common cold (The Basics)
Patient education: Preventive health care for older adults (The Basics)

Patient education: Influenza prevention (Beyond the Basics)
Patient education: Influenza symptoms and treatment (Beyond the Basics)