Flu Vaccines for Children Under 2

Medically Reviewed by Nayana Ambardekar, MD on April 18, 2023
5 min read

Although the flu is rarely serious in healthy adults, it can be much more dangerous in children, especially those ages 2 and under, and children with medical conditions and whose immune systems are weakened. Little ones are two to three times more likely to get the flu. Vaccines for children are a simple and safe way to keep your family healthy.

Several strains of influenza virus cause the flu. The types vary from year to year.

Symptoms are pretty much the same no matter what the flu type. In children, these include:

The flu itself isn't the only problem. If it weakens your child's immune system, they also could get a bacterial infection on top of it. Young children are at higher risk of problems from the flu, which include:


A flu shot is the best way to protect kids from the flu and problems that come along with it. There are two types of vaccines: one is given as a shot and the other as a spray that your child breathes in. The American Academy of Pediatrics recommends that children ages 6 months and older should get the flu shot, and that the nasal spray vaccine (FluMist) should only be used in healthy, non-pregnant people ages 2 to 49.

The vaccine your child gets in a shot is made from dead influenza virus, whereas the spray is made from a live strain. Neither cause the flu. When your child’s immune system comes in contact with the vaccine, it creates special tools called antibodies that help it fight the virus. If they get infected with the real flu later, their body will be ready to defend itself. If all goes well, their system will fight off the virus and future flus may not be as severe or last as long.

Vaccines don't always prevent the flu. Your child could have a strain of the virus that the vaccine doesn't work against. But even if this happens, the shot should ease their symptoms.

Flu shots for children don’t protect against all viruses. Your child can still get colds and infections from other viruses or other strains of the flu virus.

Most people older than 6 months should get a yearly flu vaccine. Kids younger than 2 are more likely to have problems because of the flu than older kids and adults. Children should get the vaccine by October of each year. Flu season usually runs from November to May, with a peak in February.

The flu vaccine doesn’t help kids as long as other vaccines do. It is only effective for that particular season. That's because the flu virus is always changing. Each year, the illness shifts a little bit, so a new vaccine has to be prepared that contains the most common strains for that particular year.

The first time a child younger than 9 gets a flu vaccine, they’ll need two doses at least a month apart. Kids usually get the shot in the leg or arm.

If your child has one of the following conditions, make sure they get a shot. They may be more likely to have serious problems linked to the flu:

  • Heart, lung, or kidney disease
  • Asthma
  • Diabetes or other metabolic disorders
  • Sickle cell anemia
  • HIV or other conditions that weaken the immune system
  • Treatment with cancer drugs or steroids, which suppress the immune system
  • Long-term aspirin treatment. If given to someone under age 19 who has the flu, it raises the risk of them getting Reye's syndrome, a rare but serious illness.

Yes, but they’re mild. They include:

  • Redness or soreness in the body part that got the shot
  • Low-grade fever
  • Aches

The vaccine can’t give your child the flu.

More serious side effects are rare, but your child could be allergic to the shot. Signs of allergic reaction to a flu vaccine include:

If you see any of these signs, get emergency help.

Another side effect to watch for is localized infection at the site of the injection. If there is significant swelling, redness, pus, fevers or any concerns, contact your doctor.

Flu vaccines for children may not be safe for everyone. Your child’s doctor may not want to give them a shot if they:

  • Has had severe allergic reactions to past flu vaccines
  • Has ever had Guillain-Barré syndrome, an immune system disorder
  • Is currently sick

Doctors say the vaccine has such a low amount of egg protein that it's unlikely to cause an allergic reaction in kids who have an egg allergy. If your kid does, talk to their doctor before you let them get the flu shot. Or ask about egg-free vaccines.

Many parents worry about giving their young child a flu vaccine. Some contain thimerosal, an ingredient that keeps them from going bad. Some people think there’s a link between it and developmental disorders in children. But studies haven’t found a connection. If you’re worried, ask your child's doctor about a vaccine that doesn't have thimerosal. They exist, but supplies are limited. If your child is older than 2, they can get the nasal spray vaccine, which doesn't have it.

Flu vaccines for children are some of the safest medicines we have. You may not like the idea of your child getting yet another shot, but you have to weigh the very small chance of a side effect with the much more serious risks of actually getting the flu. It’s always better to prevent an illness than to treat it.