Your Child's Immunizations: Influenza Vaccine

What Is the Flu?

Influenza — what most of us call "the flu" — is a highly contagious viral infection of the respiratory tract.

When Should People Get the Flu Vaccine?

Flu season runs from October to May. It's best to get a flu vaccine as early in the season as possible. This gives the body a chance to build up immunity to (protection from) the flu. But getting a flu vaccine later in the season is still better than not getting the vaccine at all.

Who Should Get the Flu Vaccine?

The Centers for Disease Control and Prevention (CDC) recommends a flu vaccine for everyone 6 months of age and older.

But it's especially important that those in higher-risk groups get vaccinated to avoid health problems as a result of the flu. They include:

• all kids 6 months through 4 years old
• anyone 65 years and older
• all women who are pregnant, are considering pregnancy, have recently given birth, or are breastfeeding during flu season
• anyone whose immune system is weakened from medications or illnesses (like HIV infection)
• residents of long-term care facilities, such as nursing homes
• any adult or child with chronic medical conditions, such as asthma
• kids or teens who take aspirin regularly and are at risk for developing Reye syndrome if they get the flu
• caregivers or household contacts of anyone in a high-risk group (like children younger than 5 years old, especially those younger than 6 months, and those with high-risk conditions)
• Native Americans and Alaskan natives

Babies younger than 6 months can't get the vaccine, but if their parents, other caregivers, and older kids in the household get it, that will help protect the baby. This is important because infants are more at risk for serious complications from the flu.

How Is the Flu Vaccine Given?

• Kids younger than 9 years old will get two doses of flu vaccine, spaced at least 1 month apart, this flu season if they have got fewer than two doses before July 2018. This includes kids who are getting the flu vaccine for the first time.
• Those younger than 9 who have received at least two doses of flu vaccine previously (in the same or different seasons) will only need one dose.
• Kids older than 9 need only one dose of the vaccine.

Talk to your doctor about how many doses your child needs.

What Are the Types of Flu Vaccines?

Different types of flu vaccines are available:

• The trivalent flu vaccine protects against three strains of the flu virus (usually, two types of influenza A viruses and one influenza B virus).
• The quadrivalent flu vaccine protects against four strains (usually, two types of influenza A viruses and two influenza B viruses).

What About the Nasal Flu Vaccine?

The flu vaccine is given to kids by injection with a needle (the flu shot) or by nasal spray (FluMist®). The flu shot is preferred for children of all ages because it has been shown to be safe and effective.

The nasal spray vaccine was not recommended for the last two flu seasons because it didn't work as well as the shot. A new version of it is now approved for the 2018–2019 flu season for kids who otherwise might not get a flu shot (for example, if a child is afraid of needles or if the flu shot isn't available at the doctor's office).

The nasal spray is only for healthy people ages 2 through 49. People with weakened immune systems or some health conditions (such as asthma) and pregnant women should not get the nasal spray vaccine.

Vaccine shortages and delays sometimes happen, so check with your doctor about availability.

Why Is the Flu Vaccine Recommended?

While the flu vaccine isn't 100% effective, it still greatly reduces a person's chances of catching the flu, which can be very serious. It also can make symptoms less severe if someone does still get the flu after immunization.

Even if you or your kids got the flu vaccine last year, that won't protect you this year, because flu viruses constantly change. That's why the vaccine is updated each year to include the most current strains of the virus.

Sometimes the same strains are included in the vaccine one year after the next. In this case, it's still important to get a seasonal flu shot because the body's immunity against the influenza virus declines over time.

What Are the Possible Side Effects of the Flu Vaccine?

Usually given as an injection in the upper arm, the flu shot contains killed flu viruses that will not cause someone to get the flu. But it can cause mild side effects like:

• soreness, redness, or swelling at the injection site
• a low-grade fever
• aches

The nasal spray flu vaccine contains weakened live flu viruses, so it may cause mild flu-like symptoms, including runny nose, headache, vomiting, muscle aches, and fever. 

Very rarely, the flu vaccine can cause a severe allergic reaction.

What Happens After Flu Immunization?

If your child got a flu shot and has any side effects (like soreness at the injection site, a low fever, or aches), talk to your doctor about giving either acetaminophen or ibuprofen and to find out the right dose.

A warm, damp cloth or a heating pad on the injection site may help reduce soreness, as can moving or using the arm.

What Else Should I Know?

Some things might prevent a person from getting the flu vaccine. Talk to your doctor to see if the vaccine is still recommended if your child:

• has ever had a severe reaction to a flu vaccination
• has had Guillain-Barré syndrome

In the past, it was recommended that anyone with an egg allergy talk to a doctor about whether receiving the flu vaccine was safe because it is grown inside eggs. But health experts now say that the amount of egg allergen in the vaccine is so tiny that it is safe even for kids with a severe egg allergy. This is especially important during a severe flu season.

Still, a child with an egg allergy should get the flu shot in a doctor's office, not at a supermarket, drugstore, or other venue.

If your child is sick and has a fever, talk to your doctor about rescheduling the flu shot.

When Should I Call the Doctor?

Call if:

• you aren't sure if the vaccine should be postponed or avoided
• there are problems after the immunization, such as an allergic reaction or high fever, or if you have other concerns