Every year during flu season, many of us start ducking and dodging to avoid the coughs and sneezes of family, friends and strangers. Influenza, more commonly known as the flu, is a highly contagious respiratory illness that wreaks havoc during the fall and winter months. But one of the easiest ways to avoid the flu is to get vaccinated yearly.

Why do we have to get the flu shot annually? According to the National Institutes of Health, there are two reasons a flu vaccination is needed every year:

• First, the body’s immune response from vaccination declines over time, so an annual vaccine is needed for optimal protection.
• Second, the formulation of the flu vaccine is reviewed each year and updated to keep up with the ever-changing flu viruses.

“When a person is exposed to an influenza virus, whether by infection or vaccination, their immune system will produce specific antibodies against the antigens [surface proteins] on a particular virus,” said Army Col. Margaret Yacovone, director of the Immunization Healthcare Branch at the Defense Health Agency.
Each year, approximately 2,000 influenza virus strains are compared for similarities with those that make up the current flu vaccine. They are monitored for changes or mutations in the viruses. Experts rely on the study for information about the vaccine’s ability to create an immune response, and that helps determine what virus strains to include in the next seasons’ flu vaccine.

Yacovone says this year’s vaccine protects against several flu viruses. However, there can be significant differences, or “drift,” among the various strains, she said. While vaccine effectiveness can be reduced through drift, it still provides protection against the non-drifted strains. “That’s why getting vaccinated with the influenza vaccine helps protect against getting the flu, even when the strains vary.”

The influenza virus is spread through aerosolized respiratory droplets during close contact with an infected person, animal or contaminated object. The incubation period is commonly two days, but that can range from one to four days. Because the incubation period is short, flu outbreaks can be volatile.
People who have the flu experience fever, chills, cough, sore throat, runny nose, muscle aches, headaches and fatigue.

For some people, the recovery period can take a few days, but for others, it can last up to two weeks. Complications can develop from the flu, including bronchitis, sinus and ear infections, and pneumonia, which can be life-threatening, warned Yacovone.

There are two vaccines available: a flu shot or a nasal spray mist. There are common side effects associated with both vaccines. Depending on which vaccine you get, mild side effects may occur. They include soreness and redness at the injection site, cough, nasal congestion, sore throat and chills, but most resolve within 24-48 hours. Flu vaccines are safe and are not able to infect you with the flu because the vaccines contain killed or weakened viruses.

To learn more about the flu vaccine and where you can get it, visit the Department of Health and Human Services Flu website.

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