Influenza Virus Vaccine

Definition

The flu vaccine protects a person against getting influenza, caused by the influenza virus. It is administered either by injection or by inhalation.

Description

There are two types of flu vaccine. Live attenuated influenza vaccine (LAIV) was first approved for use in 2003. It contains live, but weakened, influenza virus and is administered as a nasal spray. Inactivated influenza vaccine contains killed viruses and is given by intramuscular injection.

Because influenza changes from year to year, a flu shot, unlike other types of vaccinations, is required every year. Each year, the United States Centers for Communicable Disease Control predicts the strains of influenza that are likely to appear in the coming year. Vaccine manufacturers then make products to protect against these types of flu. These vaccines only protect against the type of influenza viruses from which they are made. They are usually of no value against other types of influenza virus.

There are three types of influenza virus: A, B, and C. They differ by the proteins on their outer surface. Type A viruses are found in many different animals, including ducks, chickens, pigs, whales, horses, and seals. Influenza B viruses circulate widely, but only among humans. Type C viruses, also only among humans, cause a very mild infection, and flu vaccines do not include protection against type C influenza.

General use

Influenza is a contagious illness. Every year, 10 to 20 percent of the U.S. population gets the flu, and over 100,000 people are hospitalized because of influenza. Symptoms of flu include fever, headache, extreme tiredness, dry cough, sore throat, runny or stuffy nose, and muscle aches. When children get the flu, they often complain of nausea and have vomiting and diarrhea, although these problems are less common in older children and adults. While influenza virus vaccines cannot give complete protection against flu, they greatly reduce the risk of flu-like infections, reduce the risk of hospitalization, and shorten the duration of these infections.

All healthy children between the ages of six months and 23 months should receive influenza vaccine because these young children do not yet have fully developed immune systems and are at increased risk of getting the flu and requiring hospital treatment. Children over the age of six months should also receive the vaccine if they have certain medical risk factors:

• asthma or other lung disease
• congenital heart disease with defects that require medications or surgery or other heart disease
• glomerulonephritis, kidney failure, or other kidney disease
• diabetes or other metabolic disease
• sickle cell disease or other anemia
• immune system problems or other anemia
• juvenile rheumatoid arthritis or any other disease needing aspirin therapy

Otherwise healthy children above the age of 23 months may have a flu shot simply to reduce the risk of influenza.

Content licensed from:

Author Info: Samuel Uretsky PharmD, Thomson Gale, Gale, Detroit, Gale Encyclopedia of Children's Health, 2006

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.