Flu experts say what they feared could happen -- has happened.
Late last winter, a panel of vaccine experts designing this season's flu shot had to make a tough choice.
They could either stick with last year's formula, even though a new strain of the flu bug was gaining strength -- or they could make a new vaccine, risking delays that could result in a shortage or maybe even no vaccine at all.
In the end, the panel voted to bring back last year's version. But now, that new flu strain has become the dominant variety, accounting for three-quarters of all cases as the disease got an unusually early start this fall.
About $83 million doses of vaccine were made, but no one really knows how much protection from the illness it gives. Vaccine experts say the choices they have to make show how tough it is to keep up with the flu virus, which mutates constantly.
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- Much of the illness and death caused by influenza can be prevented by annual influenza vaccination.
- Influenza vaccine is specifically recommended for people who are at high risk for developing serious complications as a result of influenza infection.
- These high-risk groups are:
- All people age 65 and older.
- People of any age with chronic diseases of the heart, lungs or kidneys, diabetes, immunosuppression, or severe forms of anemia.
- Residents of nursing homes and other chronic-care facilities housing patients of any age.
- Women who will be more then three months pregnant during influenza season.
- Children and teenagers who are receiving long-term aspirin therapy and who may therefore be at risk for developing Reye syndrome after an influenza virus infection.
- Overall vaccine effectiveness varies from year to year, depending upon the degree of similarity between the influenza virus strains included in the vaccine and the strain or strains that circulate during the influenza season.
- Influenza vaccine produced in the United States cannot cause influenza.
- The only type of influenza vaccine that has been licensed in the United States is made from killed influenza viruses, which cannot cause infection.
When to receive the influenza vaccine
- In the United States, influenza usually occurs from about November until April, with activity peaking between late December and early March.
- The optimal time for vaccination of persons at high risk for influenza-related medical complications is during October through November.
- It takes about 1 to 2 weeks after vaccination for antibody against influenza to develop and provide protection.
Source: http://www.cdc.gov/ncidod/diseases/flu/fluvac.htm ( The Center for Disease Control Vaccine Information Web site)