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What is influenza?

Flu (Influenza) is a viral infection that affects the upper respiratory system, which includes the nose and throat, the airways (also called bronchial tubes), and the lungs. While everyone is at risk for getting the flu, children can be more likely to get sick from this virus.

In young children, women who are pregnant, the elderly, and those with other health conditions, the flu can require them to be hospitalized. In some cases, the flu can be very serious or even deadly.

The experts at Boston Children’s care for children with flu and help them avoid complications like pneumonia that can lead them to become seriously ill.

What are flu symptoms?

Common flu symptoms include:

How long does flu last?

Your child may have some flu symptoms, or all of them. Most symptoms last about a week. But the tiredness may linger longer. If you notice the symptoms are not getting better, or are getting worse, always call your pediatrician.

Flu complications and warning signs

If your child has the flu, it’s important to be on the lookout for any complications. Always seek emergency medical care if you notice the following signs in your child:

  • fast breathing or trouble breathing
  • bluish or gray skin color (cyanosis)
  • not drinking enough fluids
  • severe or persistent vomiting
  • not waking up or not interacting
  • extreme irritability/not wanting to be held
  • flu-like symptoms improve but then return with fever and worse cough

Flu | Prevention, Diagnosis, & Treatments

Flu prevention

The best way to avoid problems from the flu is by preventing it in the first place. That’s why in Massachusetts in 2020-21, an annual flu shot (influenza vaccine) is required for everyone six months and older who is attending daycare, school, or college. The flu vaccine is also recommended for adults.

What is the flu vaccine?

Injectable flu vaccines introduce small doses of an inactivated version of the flu virus into the body so the immune system can develop antibodies that can fight the flu virus. This usually takes about two weeks to be effective. Since the flu virus changes each year, the flu shot must be given annually.

Can you get the flu even if you get vaccinated?

It’s important to know that some people may still get the flu even though they got a flu shot. When this occurs, the symptoms are usually milder and may resolve more quickly. In fact, getting a flu shot can lessen the length of the illness and also prevent serious complications from occurring.

Can the flu shot cause the flu?

The flu vaccine itself can’t cause the flu, but some people may get mild side effects from the shot. This can include fever or soreness at the injection site that goes away quickly. Even if you or your child get side effects from the flu shot, they will be much milder than getting the flu.

Flu | Programs & Services