Fighting the Flu: Flu Facts

by Food and Drug Administration (FDA)

If you haven't gotten your flu shot yet, go get it. January is not too late to get a flu shot. "Those getting vaccinated at any time will be better protected against the influenza (flu) virus," says Roland A. Levandowski, MD, a virologist in the Food and Drug Administration's Center for Biologics Evaluation and Research (CBER).

Delays in distribution of the vaccine to health-care providers have prevented some people from getting their shots in October and November — the usual time for vaccination. But the vaccine can be used in January and later with good effectiveness since the flu season lasts through March, says Levandowski.

Studies have shown the vaccine's effectiveness rate to be 70 to 90 percent in healthy young adults. In the elderly and in people with certain chronic illnesses, the vaccine sometimes doesn't prevent illness altogether, but does reduce its severity and the risk of serious complications and death.

The vaccine's most common side effect is soreness at the vaccination site for up to two days. Some people may experience post-shot fever, sore muscles and other symptoms resembling the flu that can last for one to two days. But the flu vaccine cannot actually cause flu because it contains only inactivated viruses.

The Centers for Disease Control and Prevention (CDC) and the Advisory Committee on Immunization Practices strongly recommend vaccination for the following high-risk groups and their close contacts and health-care workers:

• Adults and children who have chronic disorders of the pulmonary or cardiovascular systems, including asthma;
• Persons aged 65 years and older;
• Residents of nursing homes and other facilities that provide care for chronically ill persons;
• Adults and children who have certain underlying medical conditions that required hospitalization or regular doctor visits during the past year because of chronic disease including heart, lung or kidney disease, diabetes, asthma, anemia, or immunosuppression (for example, caused by medications or HIV infection);
• Children and teenagers (aged 6 months to 18 years) who must take aspirin regularly and therefore might be at risk for developing Reye syndrome if they get the flu; and
• Women who will be in the second or third trimester of pregnancy during the influenza season. (Pregnant women who have a high-risk condition should be immunized regardless of the stage of pregnancy.)

Some people — but not many — should avoid the flu shot. People who have had an allergic reaction to eggs or to a previous dose of influenza vaccine should consult a doctor before getting a flu shot if they plan to get the shot at a place other than their physician's office. And those with a high fever should not receive the vaccine until they feel better.

Flu Facts

Influenza, commonly called the flu, is an infection of the respiratory tract caused by the influenza virus. Signs of the flu include sudden onset of headache, chills, and feeling generally miserable. Respiratory symptoms like nasal congestion, cough and sore throat appear, and the flu sufferer often experiences extreme fatigue and muscle aches in the back and legs. Fever between 100 and 103 degrees Fahrenheit is typical in adults, and is often even higher in children.

Scientists have classified influenza viruses as types A, B and C. Type A is the most common and leads to the most serious epidemics. Type B can cause epidemics, but usually produces a milder disease than type A. Type C viruses have usually been associated with symptoms suggesting a common cold.

Influenza rarely causes stomach upset; however, young children may have nausea and vomiting during the most severe phase of the flu. What is popularly called "stomach flu" is usually another malady: gastroenteritis. Bacteria, toxins, or viruses other than influenza are the usual causes of gastroenteritis.

Serious illnesses like strep throat, measles, and chickenpox sometimes have flu-like symptoms. It's important to see a doctor if symptoms persist, become severe or localized in the throat, stomach or lungs, or if other symptoms such as skin rash, vomiting or behavioral changes occur.

Influenza and other respiratory viruses can be transmitted in one of two ways: by inhaling infectious particles in the air (like respiratory secretions from a cough or sneeze), or by touching respiratory secretions, usually on the skin, of an already-infected person and then touching one's eyes or nose. Shaking hands, for example, with an infected person, or touching environmental surfaces (like doorknobs or handrails) that have been contaminated with flu virus particles and then touching your eyes or nose may transmit the virus.

"In addition to getting vaccinated, the single most important step people can take to help prevent getting the flu is to wash their hands," says Linda Lambert, PhD, influenza program officer with the National Institute of Allergy and Infectious Diseases. Hand washing is especially important after interacting with children, according to Lambert, since children are very susceptible to flu and are the primary spreaders of the virus in the community. Lambert also recommends disinfecting environmental surfaces in the home when someone is sick with the flu since the virus can live for several hours on these surfaces. Using virus-killing disinfectant on telephones, doorknobs, and computer keyboards, for example, can help prevent transmission to other family members. "And if you have the flu," says Lambert, "always use disposable tissues when coughing or sneezing and throw away the tissue immediately to help prevent infectious particles from spreading to someone else."

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.