For Your Health: CDC: Some vaccinated test positive for influenza

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By Donny Gill

The Centers for Disease Control has received reports of some people who were vaccinated against influenza becoming ill and testing positive for influenza. This occurs every season. It’s not possible at this time to say whether or not there is more of this happening this season than usual.

This is an early season, with more influenza activity being reported at this time than during recent flu seasons. The CDC is watching the situation closely and will provide additional information. There are, however, a number of reasons why people who got a vaccine can still get influenza this season.

1. People can be exposed to an influenza virus shortly before getting vaccinated or during the two-week period it takes the body to gain protection after getting vaccinated.

2. A person might be exposed to an influenza virus not included in the seasonal flu vaccine. There are many different influenza viruses that circulate every year. The composition of the flu shot is reviewed each season and updated if needed to protect against the three viruses research suggests will be most common.

3. Some can get infected with an influenza virus included in the vaccine despite getting vaccinated. Protection provided by influenza vaccination can vary widely, based in part on health and age factors of the person vaccinated. In general, the flu vaccine works best among young, healthy adults and older children. Influenza vaccination is not a perfect tool, but it is the best tool at our disposal.

To estimate how well influenza vaccines work each year, the CDC works with researchers at universities and hospitals, conducting observational studies using laboratory-confirmed influenza as the outcome. There is insufficient data to provide estimates about vaccine effectiveness for this season, but the center hopes to have interim effectiveness estimates within the next five weeks.

It’s important health care providers and patients remember antiviral medications are a second line of defense against influenza. The CDC has recommendations on the use of these medications, which are sold commercially as Tamiflu and Relenza, to treat influenza.

Antiviral treatment as early as possible is recommended for any patient with confirmed or suspected influenza, including young children, people 65 and older, people with certain underlying medical conditions and pregnant women.

A full list of those considered high risk is available at www.cdc.gov/flu/about/disease/high_risk.htm. More information about antiviral drugs and the CDC’s recommendations are available at www.cdc.gov/flu/professionals/antivirals/index.htm.

Donny Gill is a health educator at the Hardin County Health Department. He can be reached at donny.gill@ky.gov.