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Flu Vaccines and Serious Childhood Illness

Should children with serious illnesses get a flu vaccine?

Most children with serious illnesses are encouraged to get a flu shot each year. Talk to your child’s care team about their specific situation.

An annual flu shot is recommended for all children older than 6 months. The Centers for Disease Control and Prevention, the American Academy of Pediatrics, and the Infectious Diseases Society of America agree on the recommendation.
Your child’s care team might not recommend if your child is not likely to respond to the vaccine. But it is important to remember they are not likely to be harmed by the vaccine, either.

Your child might not respond to the flu vaccine if they have:

  • Received strong chemotherapy
  • Received anti B-cell antibodies within 6 months

Depending on your child’s diagnosis and treatment plan, the care team might recommend waiting on a flu vaccine.

Transplant, cellular (CAR T-cell) therapy, and gene therapy patients may get a flu shot 6 months after their infusion. If there is a flu outbreak in your community, they may receive a flu shot 4 months after transplant.

The flu explained

Flu is short for influenza. It is a respiratory illness caused by a flu virus. Flu symptoms include:

  • Fever
  • Chills
  • Cough
  • Sore throat
  • Runny nose
  • Body aches
  • Headaches
  • Fatigue

In severe cases, flu can cause breathing problems, pneumonia, or other life-threatening complications.

The flu vaccine is important

A vaccine strengthens the immune system to protect the body from illness. It builds up the body’s natural defenses (immunity) against infection.

The flu vaccine protects people from developing the flu. It causes a person to develop antibodies that recognize and fight flu viruses.

People need a flu vaccine once a year. This is because the vaccine is different each year. Flu viruses constantly change. And your body’s immune response decreases over time.

Most people who get flu recover in a few days to less than 2 weeks. But some people develop more serious symptoms or complications. Some complications can be life-threatening.

Sinus and ear infections are examples of moderate complications from flu. Pneumonia is an example of a serious flu complication.

Flu vaccination is especially important for people with certain medical conditions including:

  • Asthma
  • Heart disease
  • Diabetes

Flu also can make these chronic medical problems worse. For example, people with asthma may experience asthma attacks while they have flu. People with heart disease may become worse because of the flu.

Vaccines for family members

If a child in your family has a serious illness, it is important for family members to get the flu vaccine. Young children and those with serious illnesses are at higher risk for life-threatening complications from the flu. Having all family members and caregivers vaccinated helps to protect your child.

Some people may still get the flu after being vaccinated. Even if you do get the flu, you may not get as sick because your body is better able to defend itself.

Types of flu vaccine

There are 2 main ways the flu vaccine is given:

  • Flu shot (needle injection)
  • Nasal spray (Flumist®)

Children with weakened immune systems should not get the nasal spray. It has a weakened live form of the flu virus. People who live in the same household as your child should not receive the nasal spray either.

The flu shot is made with dead (inactivated) flu viruses. It is safe for people with weakened immune systems. Your child can take it at least 2 weeks before chemotherapy. Or they can take it between chemotherapy cycles.

There are several different types of flu shots. Most are given in the muscle of the upper arm. Infants and very young children may get the flu shot in the upper thigh.

Your doctor will recommend the best flu vaccine for your child.

The best time to get the flu vaccine

If possible, get the flu shot in September or October. But getting one any time during the flu season can help protect you. In general, flu cases usually start to rise in October, peak in December through February, and can last until May.

It takes about 2 weeks to develop an immune response after the flu vaccine.

In certain cases, children may need 2 doses of the flu vaccine. Your doctor will tell you if this necessary.

The flu and COVID-19 

It is possible to have both flu and COVID-19 at the same time. But it is hard to predict how often this might happen. Both COVID-19 and flu are respiratory infections. The symptoms of COVID-19 and flu can be similar.

The flu vaccine will not protect you from COVID-19. And the COVID-19

If you have symptoms, your doctor probably will test for both. The test results can help your doctor decide the best treatment.

Antiviral medicines for the flu

Antiviral medicines help to keep the flu virus from reproducing. Flu antiviral medicines can reduce the severity and duration of symptoms.

They work best when started within 2 days of becoming sick. Several antiviral medicines are available in pill, liquid, inhaled, and IV form. Flu antiviral medicines only work on the flu virus and are not used for other viral infection.

Flu vaccines do not cause flu illness

Flu vaccines do not give you the flu. Flu shots are made with only part of the flu virus or with “killed virus.” It is not active. The FluMist® nasal spray contains a weakened form of the live virus that cannot cause flu illness.

Some people may have mild side effects after a flu vaccine. After a flu shot, you might notice:

  • Redness or swelling at the injection site
  • Headache
  • Fever
  • Fatigue
  • Nausea
  • Body aches

These symptoms are part of the normal immune response. Your body is making antibodies against the flu. They usually go away after a few days.

There is a chance you can get the flu even if you got a flu vaccine.

But, if you get the vaccine and later get the flu, you’re likely to get less sick than if you had not been vaccinated.

How effective the flu vaccine is depends on the match of the vaccine to the type of flu virus infection. You might be infected with a different type of flu virus. There are two main types or strains of flu:

  • Type A (influenza A)
  • Type B (influenza B)

Also, some people have a weaker immune response to the vaccine. You can lose your protection over time. Even if you do get the flu, your risk for severe illness is lower.

Flu vaccines are safe if you have an egg allergy

Egg-free flu vaccines are available for patients with an egg allergy. But flu vaccines have a small amount of egg protein.

In most people with a history of egg allergy, the flu vaccine does not cause an allergic reaction. Some people with a history of egg allergy may need to get the flu vaccine under medical supervision.

Be sure to let your health care provider know if you have an egg allergy.

How the flu spreads

Flu spreads easily person to person:

  • Through droplets in the air when someone coughs or sneezes
  • By touching surfaces with the virus.

You may be able to spread the flu virus before you even know you are sick. You may be contagious for 7 days or longer after becoming sick.

How to prevent the flu?

The best way to prevent the flu is to get a yearly flu vaccine.

Other ways to help stop the spread of flu include:

  • Washing hands often
  • Covering coughs and sneezes
  • Staying away from people who are sick

Wearing a face mask can also help prevent respiratory viruses, including flu and COVID-19.

Flu complication risks

Those at risk for serious illness with the flu include:

  • Children under age 5
  • Adults over age 65
  • People with chronic health conditions

Close monitoring is especially important for people with weak immune systems. However, even healthy children that get the flu can become very sick. Talk to your doctor about any symptoms that worry you.

Possible problems with the flu

Most people have mild or moderate flu symptoms. But some people can get very sick. Watch for emergency warning signs such as:

  • Fever above 104°F
  • Trouble breathing
  • Chest pain or pressure
  • Severe muscle pain
  • Confusion or decreased alertness
  • Lips or face turning blue
  • Seizures
  • Dehydration (not urinating, lack of tears)

This list includes some common warning signs, but there may be others. In a medical emergency, go to the emergency room or call 911.

How to treat the flu

To help manage symptoms of the flu:

  • Drink plenty of fluids
  • Rest
  • Treat symptoms using over-the-counter medicines as recommended by your doctor
  • Take flu antiviral medicines as prescribed by your doctor
  • Watch for worsening of symptoms or health problems such as ear infections
  • Monitor for emergency warning signs such as dehydration, seizures, or breathing problems

More information about flu and flu vaccines

Key points

  • The flu vaccine is a safe, effective way to prevent the flu.
  • If your child has a serious illness or a compromised immune system, talk with your care team about the flu vaccine.
  • Regular handwashing, covering coughing and sneezing, and staying away from people who are sick can help you prevent the flu.
  • If you do get the flu, be sure to watch for symptoms of complications.

does not endorse any branded product mentioned in this article.

Reviewed: October 2022