The Flu Vaccine for Children and Toddlers

If you're thinking about skipping flu vaccination for your family this year, then your child has probably never had influenza, which can leave them coughing, feverish, and completely wiped out for a whole week. "Unfortunately, many parents consider the flu to be nothing more than a slightly nastier version of a cold. It's actually a very serious, potentially fatal illness," says Parents advisor Neal Halsey, M.D., director of the Institute for Vaccine Safety at Johns Hopkins Bloomberg School of Public Health, in Baltimore. Possible complications of the flu include pneumonia, antibiotic-resistant staph infections, and ear and sinus infections.

Amazingly, many young children remain unvaccinated, despite the fact that an estimated 20,000 kids under the age of 5 need to be hospitalized for influenza complications each year, according to the National Foundation for Infectious Diseases. Kids who have a chronic medical condition like asthma or diabetes have a higher risk; they’re five times more likely to be hospitalized than healthier kids.

These statistics help explain why the Centers for Disease Control and Prevention (CDC) recommends that all children older than 6 months get a vaccination. Here’s what you need to know about the flu vaccine for children.

When Should Kids Get the Flu Shot?

Most people get immunized as soon as the vaccine is available in October or November, but your child can benefit from getting the shot as late as April. "It's not uncommon to still have flu strains circulating throughout the spring," says Kathleen Gutierrez, M.D., a pediatric-infectious-disease expert at Lucile Packard Children's Hospital at Stanford, in Palo Alto, California. Keep in mind, though, that your child's immune system needs two to four weeks to build up protective antibodies, so they could still get sick if they're exposed to an influenza virus soon after they're vaccinated.

If your child is younger than 9 and getting the flu vaccine for the first time, they'll need a second dose of the shot within four to six weeks. This two-step process gives their immature immune system time to respond.

What About the Nasal Spray Flu Vaccine?

The shot isn't your family's only option for protection against influenza. Your child may be able to get misted, too: A FluMist nasal-spray vaccine is approved for use by those 2 years to 49 years old (but not pregnant people). But children of any age who have asthma, recurrent wheezing problems, or weakened immune systems shouldn't use the nasal spray because it may aggravate their symptoms. The mist’s effectiveness changes between seasons, much like the flu shot, and some insurance companies may not cover it.

Flu Vaccine Side Effects for Kids

Despite common misconception, your child is not going to get sick from the flu vaccine. The nasal-spray vaccine is made with live, but extremely weak, influenza strains that won't cause the illness.

Nevertheless, some children develop mild flu-like symptoms within 48 hours of getting either type of vaccine. They might include redness and soreness at the injection site, low-grade fever, headache, muscle aches, and nausea. "These reactions are actually a good sign that your child's body is busy building flu-fighting antibodies," explains Susan Rehm, M.D., medical director of the National Foundation for Infectious Diseases. Any side effects should subside within a day or two.

Some parents might be asking, "Does the flu vaccine cause autism?" Absolutely not, experts say. The flu shot is the only immunization given to children that may still contain small amounts of thimerosal, a mercury-based preservative that some claim causes autism. But, thankfully, numerous studies have found no association between vaccines containing thimerosal and autism. Even so, most pediatricians now offer preservative-free shots for young patients whose parents request them. If your child is older than 2, you can also opt for the nasal spray, which doesn't contain thimerosal.

How Effective is the Flu Vaccine for Kids?

Flu shot effectiveness changes every year, but success rates usually range from 40-60%. Still, even if your child does get influenza, the shot will typically reduce the severity of the illness. Indeed, a 2022 study published in Clinical Infectious Diseases found that flu vaccines reduced children’s risk of life-threatening influenza by 75%. Getting kids vaccinated may also protect other household members, including those at higher risk for flu complications.

My Child Has Flu Symptoms—Now What?

If your vaccinated or unvaccinated child develops flu symptoms—a fever, chills, muscle aches, headache, extreme fatigue, runny nose, sore throat, and a hacking cough—get them to the doctor quickly. A rapid flu test can determine in about 30 minutes whether it's the flu. If it is, your doctor might suggest an antiviral drug , which must begin within 48 hours of the onset of symptoms. Antiviral drugs may be particularly helpful for kids with underlying conditions that might put them at higher risk for severe influenza. Children older than 14 days can take the liquid drug Tamiflu; kids 7 and up can take Relenza, a spray that's inhaled through the mouth. Using an antiviral drug also reduces the odds that other family members will get sick.