Since my retirement from the Centers for the Disease Control and Prevention (CDC), I am often asked questions regarding this respiratory agent. There is no question that this infectious disease has a rather dubious history along with a certain amount of dread for many of us. It is my hope to shed some light on this subject using data provided by the CDC(March, 2009). Moreover, I plan to present this information in a series of timely blogs (hopefully) for all those who may have an interest in the subject

WHAT IS INFLUENZA (ALSO CALLED FLU)?

The flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness and can lead to death. The best way to prevent the flu is by getting a flu vaccination each year.

Every year in the United States, on average:

    * 5% to 20% of the population get the flu;
    * more than 200,000 people are hospitalized from flu-related complications; and
    * about 36,000 people die from flu-related causes.

Some people, such as people older than 50, young children, and people with certain health conditions (such as asthma, diabetes, or heart disease), are at high risk for serious flu complications.

SYMPTOMS OF FLU:

    * fever (usually high)
    * headache
    * extreme tiredness
    * dry cough
    * sore throat
    * runny or stuffy nose
    * muscle aches
    * Stomach symptoms, such as nausea, vomiting, and diarrhea, also can occur but are more common in children than adults

COMPLICATIONS OF FLU

Complications of flu can include bacterial pneumonia, ear infections, sinus infections, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes.

HOW FLU SPREADS

Flu viruses are thought to spread mainly from person to person through coughing or sneezing by people with influenza. Sometimes people may become infected by touching something with flu viruses on it and then touching their mouth or nose. Most healthy adults are able to infect others beginning one day before symptoms develop and up to five days after becoming sick, which means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick.

PREVENTING SEASONAL FLU: GET VACCINATED

The single best way to prevent the flu is to get a flu vaccination each year. There are two types of vaccines:

    * The "flu shot" – an inactivated vaccine (containing killed virus) that is given with a needle. The flu shot is approved for use in people SIX months of age and older, including healthy people and people with chronic medical conditions.
    * The nasal-spray flu vaccine – a vaccine made with live, weakened flu viruses that do not cause the flu (sometimes called LAIV for “Live Attenuated Influenza Vaccine”). LAIV is approved for use in healthy* people 2-49 years of age who are not pregnant.

Use of the Nasal Spray Flu Vaccine

Vaccination with the nasal-spray flu vaccine is an option for healthy* people 2-49 years of age who are not pregnant, even healthy persons who live with or care for those in a high risk group. The one exception is healthy persons who care for persons with severely weakened immune systems who require a protected environment; these healthy persons should get the inactivated vaccine

About two weeks after vaccination, antibodies develop that protect against influenza virus infection. Flu vaccines will not protect against flu-like illnesses caused by non-influenza viruses.

WHEN TO GET VACCINATED

Yearly flu vaccination should begin in September or as soon as vaccine is available and continue throughout the influenza season, into December, January, and beyond. This is because the timing and duration of influenza seasons vary. Although influenza outbreaks can happen as early as October, most of the time influenza activity peaks in January or later.

WHO SHOULD GET VACCINATED?

People who should get vaccinated each year are:
    1. Children aged 6 months up to their 19th birthday
    2. Pregnant women
    3. People 50 years of age and older
    4. People of any age with certain chronic medical conditions
    5. People who live in nursing homes and other long-term care facilities
    6. People who live with or care for those at high risk for complications from flu, including:
        a. Health care workers
        b. Household contacts of persons at high risk for complications from the flu
        c. Household contacts and non-home caregivers of children less than 6 months of age (these children are too young to be vaccinated)

.

WHO SHOULD NOT BE VACCINATED

Some people should not be vaccinated without first consulting a physician. They include:

    * People who have a severe allergy to chicken eggs.
    * People who have had a severe reaction to an influenza vaccination in the past.
    * People who developed Guillian-Barré syndrome (GBS) within 6 weeks of getting an influenza vaccine previously.
    * Children less than 6 months of age (influenza vaccine is not approved for use in this age group).
    * People who have a moderate or severe illness with a fever should wait to get vaccinated until their symptoms lessen.

If you have questions about whether you should get a flu vaccine, consult your health-care provider.

* "Healthy" indicates persons who do not have an underlying medical condition that predisposes them to influenza complications.