With the supply of flu vaccine only half what was expected, shots are being limited to those at high risk of flu complications. Who qualifies for a flu shot, and what should you do if you aren't in a priority group?

Find out the answers to these questions — and more. The following FAQ brings you up to speed on what you need to know about this year's flu season.

The Centers for Disease Control and Prevention (CDC) and the Department of Health and Human Services (HHS) recommends giving priority for influenza vaccination to people who are at high risk of developing flu-related complications.

People considered at high risk of complications include:

• Children age 6 months to 23 months
• People age 65 or older
• People age 2 to 64 with a chronic medical condition — such as asthma, diabetes, heart disease or lung disease — that could predispose them to complications
• Pregnant women
• Residents of chronic care facilities
• Healthcare workers who have direct patient contact
• Children on chronic aspirin therapy
• Close household contacts of children less than 6 months of age

The CDC and HHS asks anyone not at high risk of complications — that is, not in any of the groups outlined above — to defer or forego their flu vaccine this year. This frees up the vaccine supply for those individuals who need it most.

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If you're allergic to eggs or any components of the vaccine, or if you have a history of Guillain-Barre syndrome, talk with your doctor before getting a flu vaccine. Also, if you're experiencing an illness with high fever, wait until you improve before getting vaccinated.

Influenza is a serious public health concern, accounting for approximately 36,000 deaths of adults and children and more than 200,000 hospitalizations during an average year in the United States.

Besides vaccination, other measures can protect you and help prevent the spread of the flu to others:

• Practice good hygiene. Cover your mouth and nose with a tissue when you cough or sneeze. Wash your hands or use alcohol-based hand sanitizers often. Avoid touching your eyes, nose or mouth whenever possible. Avoid crowds when the flu is most prevalent in your area.
• Use antiviral medicine. For some, antivirals (amantadine, rimantadine, oseltamivir) may be an option for preventing flu. However, these medicines are available only through a prescription, so you'll need to talk with your doctor. Ideally, antivirals are best used in conjunction with the vaccine and not as a substitute. But given the vaccine shortage, your doctor may opt to use these medicines as a preventive measure this year.

Two different kinds of flu vaccine are available in limited quantities this flu season:

• Shot (inactivated vaccine). This is the type of flu vaccine you're probably most familiar with. The vaccine is injected into your upper arm muscle. The viruses in the vaccine are killed (inactivated). You won't develop the flu after you get a flu shot, but your body will still be able to develop the antibodies necessary to ward off the season's influenza viruses.
• Nasal spray (live, attenuated vaccine). The nasal spray vaccine (FluMist) is administered through your nose. The viruses in the vaccine work their way into your system through your mucous membranes. Your body then develops antibodies to protect you from the flu. The nasal spray is more expensive than the shot and usually isn't covered by insurance or Medicare.

Both the inactivated and live, attenuated vaccines protect you from influenza. But there are differences you should take into consideration before deciding between the two.

You need to be vaccinated for the flu each year because the vaccine changes from year to year. The flu vaccine you got last year wasn't designed to fight the virus strains in circulation this year.

Influenza viruses mutate so quickly that they can render one season's vaccine ineffective by the next season. An advisory committee meets early in the year to estimate which strains of influenza virus will be most prevalent during the upcoming flu season, and the manufacturers produce vaccine based on those recommendations.

The best time to get your flu vaccine is during October or November. After getting vaccinated, it takes about two weeks for your body to develop resistance to the viruses in the vaccine. Vaccination early in the flu season gives you the best odds at avoiding illness. And with this year's shortage, if you wait too long you may find yourself out of luck — there may not be any vaccine left.

Both the inactivated and live, attenuated vaccines include antigens to protect against two strains of type A influenza and one strain of type B influenza. One of the two strains of type A influenza included in the vaccine is the Fujian strain — the influenza virus responsible for more than 90 percent of the flu cases reported last year.

Children age 8 or younger require two doses of the vaccine if it's the first time they've ever been vaccinated for influenza. That's because children don't develop an adequate antibody level the first time they get the vaccine. Antibodies help fight the virus if it enters your child's system.

After being vaccinated for the flu one season, children need only one dose of the vaccine in subsequent years. If your child received only one dose of the vaccine last year, he or she needs only one dose this year. Two doses are recommended only for those children who have never been vaccinated before.

If your child can't get two doses of vaccine this year because of the shortage, one dose may still offer some protection.

First of all, don't go to work or send your children to school. Those are the worst things you can do — you'll risk spreading this contagious disease to someone else.

To relieve your symptoms:

• Rest
• Drink plenty of fluids
• Avoid alcohol and tobacco
• Consider over-the-counter medicine, such as acetaminophen (Tylenol, others), to ease the discomfort associated with muscle aches or fever, but don't give aspirin to children or teenagers
• Use antiviral medications if prescribed by your doctor

Be sure to monitor yourself. If you start feeling worse, consult your doctor to make sure you're not developing a flu-related complication.

Complications include bacterial infection, pneumonia and dehydration. If you have a chronic medical condition, you may experience a worsening of that condition. Sinus and ear infections can develop in children.

In addition to working as a preventive measure, antiviral medications also help treat influenza. These medicines won't cure influenza, but they can help decrease the severity of your symptoms and reduce the duration of your illness by one to two days.

To be most effective, you should take an antiviral medication within 48 hours of the onset of your symptoms. These drugs are available only by your doctor's prescription.

The antiviral medications approved by the Food and Drug Administration for treating influenza include:

• Amantadine (Symmetrel)
• Rimantadine (Flumadine)
• Zanamivir (Relenza)
• Oseltamivir (Tamiflu)

Each of these drugs carries with it different possible side effects, such as lightheadedness, nausea, loss of appetite and difficulty breathing. Discuss possible side effects with your doctor before starting on any antiviral medication.