It is caused by the influenza virus, which spreads from
infected persons to the nose or throat of others.

Other illmesses can have the same symtoms and are often
mistaken for influenza. But only an illness caused by the influenza virus is really influenza.

Anyone can get influenza. For most people, it lasts only a few days. It can cause:
fever sore throat chills fatigue
cough headache muscle aches

Some people get much sicker. Influenza can lead to
pneumonia and can be dangerous for people with heart or
breathing conditions. It can cause high fever and seizures
in children. Influenza kills about 36,000 people each year
in the United States, mostly among the elderly.

Influenza vaccine can prevent influenza.

There are two types of influenza vaccine:

An Inactivated (killed) vaccine, given as a shot, has been used in the United States for many years.

A live, weakened vaccine was licensed in 2003. It is sprayed into the nostrils. This vaccine is described in a separate Vaccine Information Statement.

Influenza vaccine prevents serious illness caused by the influenza virus. It will not prevent "influenza like" illnesses caused by other viruses.

It takes about 2 weeks for protection to develop after the shot, and protection can last up to a year

Inactivated influenza vaccine may be given at the same time
as other vaccines, including pneumococcal vaccine.

Some inactivated influenza vaccine contains thimerosal, a
preservative that contains mercury. Some people believe thimerosal may be related to developmental problems in children. In 2004 the Institute of Medicine published a report
concluding that, based on scientific studies, ther is no evidence
of such a relationship. If you are concerned about thimerosal, ask your doctor aboout thimerosal-free influenza vaccine.

Influenza vaccine can be given to people 6 months of age
and older. It is recommended for people who are at risk of serious influenza or its complications, and for people who can spread influenza to those at high risk (including all household members):

People at high risk for complocations from influenza:

All Children 6-23 months of age
People 65 years of age or older
Residents of long-term care facilities housing persons with chronic medical conditions.
People who have long-term health problems with - heart disease - kidney disease
- lung disease - metabolic disease, such as diabetes - asthma - anemia, and other blood disorders
People with certain conditions( such as neuromuscular disorders) that can cause breathing problems.
People with a weakened immune system due to: - HIV/AIDS or other diseases affecting the immune system
long-term treatment with drugs such as steroids cancer treatment with x-rays or drugs
People 6 months to 18 months of age on long-term asprin treatment( these people could develop Reye Syndrome if they got influenza).

People who can spread influenza to thoses at high risk:

Household contacts and out-of-home caretakers of infants from 0-23 months of age.
Physicians, nurses, family members, or anyone else in close contact with people at risk of serious influenza.

Influenza vaccine is also recommended for adults 50-64 years of age and anyone else who wants to reduce their chance of catching influenza.

An annual flu shot should be considered for:

People who provide essential community services.

People living in dormitories or under other crowded conditions, to prevent outbreaks.
People at high risk of influenza complications who travel to the Southern hemisphere between April and September, or tothe tropics or in organized tourists groups at any time.