Epidemiology Corner

October 15, 1999

Influenza

Epidemics of influenza occur during the winter months nearly every year and are responsible for approximately 20,000 deaths per year in the United States. Influenza viruses cause disease in all age groups, but rates of serious morbidity and mortality are highest among persons 65 years and persons of any age who have medical conditions that place them at high risk for complications from influenza.

The optimal time to vaccinate people in high-risk groups is usually October through mid-November. Protection develops one to two weeks after the shot and may last up to a year. The viruses that cause influenza often change and the influenza vaccine is updated each year by replacing at least one of the vaccine viruses with a newer one.

People at risk for acquiring a serious case of influenza, or complications, or people in close contact with them, should get the vaccine. These include:

• Everyone 65 years of age or older.

• Residents of long term care facilities housing people with chronic medical conditions.

• Anyone who has a serious long-term health problem with heart disease, lung disease, asthma, kidney disease, metabolic disease, such as diabetes, anemia and other blood disorders.

• Anyone whose immune system is weakened because of HIV/AIDS or other diseases that affect the immune system; treatment with drugs such as long-term steroids; cancer treatment with x-rays or drugs.

• Anyone 6 months to 18 years on long-term aspirin treatment (who could develop Reye Syndrome if they catch influenza).

• Women who will be more than three months pregnant during the influenza season.

• Physicians, nurses or anyone else coming in close contact with people at risk of serious influenza.

For further information about influenza vaccine and availability, contact the Immunization Bureau at (713) 794-9267 or Employee Health at (713) 558-3565.

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