It's That Time of Year Again
Have You Had Your Flu Shot?

The chilly fall evenings bring thoughts of sweaters, holiday shopping and, inevitably, another flu season. But it's not too late to guard against the flu, also called influenza, with an annual shot.

"In general, vaccine time is from Labor Day to Thanksgiving, and people need to get their vaccine as early as they can," says Dr. W. Paul Glezen with the Influenza Research Center at Baylor College of Medicine. The flu vaccine generally takes about two weeks to reach maximum effectiveness against the virus in adults and older children; young children who have not had a flu shot before or who have had less experience with natural infection may require two doses, two weeks apart, says Dr. Glezen.

Although the peak activity for flu season usually takes place between December and March, early outbreaks can occur, providing another good reason to get a flu shot now. Dr. Glezen cites the recent example of the 1991-1992 flu season that arrived early, peaking the second week of November.

The vaccine is updated every year to reflect the influenza activity around the world as observed by the World Health Organization. This year's vaccine includes two type A strains - A/Sydney and A/Beijing - and one type B strain - the B/Beijing. The strains are named according to the area of the world where they were first identified.

"The critical thing is to recognize that the nature of influenza is to change its genetic code year after year and that last year's flu vaccine is highly unlikely to protect you this year," says Dr. Charles Ericsson, medical director of The University of Texas-Houston Travel Medicine Center at Memorial Hermann Hospital. Doctors also stress the need for a flu shot each year because a person's immunity can decrease during the time between shots.

According to the Texas Department of Health, complications from the flu can lead to as many as 20,000 deaths in the United States each year, the majority occurring among people 65 years and older. Symptoms of the flu can include fever, cough, sore throat, runny or stuffy nose, headache, muscle aches and extreme fatigue.

In addition to people age 65 or older, also at high risk are:

• Residents of nursing homes and other chronic care facilities;
• People with chronic heart and lung disorders;
• Children with asthma;
• People with chronic metabolic diseases, diabetes, kidney or blood problems, or weakened immune systems;
• Children 18 and younger on long-term aspirin therapy, putting them at risk of developing Reye syndrome after influenza;
• Women in the second or third trimester of pregnancy during flu season and pregnant women with a medical condition that increases risk for flu-related complications.

It is also recommended that those living with someone in a high-risk group be vaccinated as well as any individuals working in health care facilities who may come in contact with these groups.

Dr. Ericsson says travellers planning to take international flights during flu season should also consider getting vaccinated because, in the confines of an airplane, there is a lot of opportunity to pass the flu from one person to the next. If travellers are planning a trip to the Southern Hemisphere during its flu season, he advises those travellers get immunized when they arrive at their destination. Dr. Ericsson feels health care professionals can do a better job of reminding their patients not only about getting the flu vaccine but also about keeping all of their immunizations up-to-date.

Because the flu vaccine is grown in eggs and egg protein may be leftover in the vaccine, those individuals who are allergic to eggs should not get the flu shot. "They can be skin tested with the vaccine before they receive it to determine the reaction," says Dr. Glezen, a Baylor professor of microbiology and immunology. "It's not a subtle thing. One really has to be allergic to eggs."

A new drug to treat the flu once it occurs was just recently approved by the Food and Drug Administration. Called Relenza (zanamivir), the medication is inhaled orally and acts against both the A and B strains. Other medications to treat the flu - Symmetrel (amantadine) and Flumadine (rimantadine) are only effective against the A strains. These medications can decrease the severity and the length of time a person is ill when given within 48 hours after the onset of symptoms.

As the News goes to press...

According to a study published in the Oct. 28 issue of the New England Journal of Medicine, taking the drug oseltamivir orally daily for six weeks can prevent influenza. Baylor College of Medicine was one of six U.S. sites where the drug was tested. The TMC News will have more details in the November 15 issue.

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©2006 Texas Medical Center

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