Where does last week's abrupt announcement of a major U.S. flu shot shortage leave you, as the flu season gets underway? Annoyed, certainly. Mad, maybe. Worried, perhaps, or confused, judging from the flood of calls to clinics and doctor's offices scrambling to advise patients even as health workers revised or canceled immunization schedules.

The tumult began after British health authorities halted the shipment of nearly 50 million doses of Fluvirin -- roughly half the anticipated U.S. supply of flu vaccine -- citing potential contamination.

In response, doctors and health authorities were urging healthy adults to leave vaccines for those who need them most: high-risk patients, including young children, seniors and those with chronic health conditions such as asthma and diabetes. Remaining vaccine stocks include about 54 million doses of Fluzone, the rival vaccine from manufacturer Aventis Pasteur, plus a million or so doses of FluMist, the nose-spray vaccine manufactured by Gaithersburg-based MedImmune. But FluMist's use of a weakened but live virus makes it unsuitable for high-risk groups.

You have questions? We thought so.

How do I know if I'm in a high-risk group?

People in all of the following groups, say health officials, should get immunized because they are at elevated risk of life-threatening complications if they contract the flu:

* All infants and toddlers ages 6 to 23 months.

* Anyone ages 2-64 with a chronic medical condition (for example, asthma or diabetes).

* Any child age 6 months -- 18 years on regular aspirin therapy.

* Anyone living in a nursing home or long-term-care facility.

* Women who will are likely to be pregnant this fall or winter.

* All adults 65 and over regardless of where they live.

In addition, for the protection of others, the CDC recommends immunizations for:

* Anyone who cares for or lives with an infant under 6 months old.

* Health workers involved in direct patient care.

Okay, so if I qualify as high-risk, or someone in my family does, what do I do now?

Where you can get the shot depends on your age and circumstances.

* For children, your best bet is your pediatrician or family physician, as Maryland and D.C. community flu clinics cannot give shots to children under age 9, and Virginia flu clinics cannot give them to anyone under 18, according to Maxim Health Systems spokesman Steve Wright. There's some good news for parents of little ones: The Centers for Disease Control and Prevention (CDC) does not anticipate a shortage of vaccine for infants and toddlers; all the pediatric vaccine was manufactured by Aventis, said CDC spokeswoman Kathy Harben. Two doses given a month apart provide best protection to a child receiving a vaccine for the first time. Babies younger than 6 months should not be immunized (but their caretakers should be).

* Residents of nursing homes and assisted-living facilities should ask administrators about on-site immunization plans. Local home care agencies, which typically run these clinics, say they intend to go forward with them -- as long as vaccine is available. As of last Wednesday, MedStar Health Visiting Nurse Association could only commit to running senior center clinics through Oct. 15, according to VNA vice president Teresa Cunningham. Senior living communities may also consider administering antiviral drugs, which help prevent flu. Alternatively, residents may need to look to their physician or a clinic.

* People working at larger health care sites may be able to get shots through their employers -- but only staff involved in direct patient care are eligible. Others involved in health care should seek out a flu vaccine from their personal physician or from a clinic. Everyone else who qualifies as "high-risk" should try to schedule a flu shot with your family physician. If your doctor doesn't have available vaccine, check with other local doctors. Do not believe the rumors that no doctors in the area have vaccine, but don't wait to make the call, either.

I'm supposed to get a shot. Will I be able to get one a public immunization clinic?

Maybe if you hustle. Most public clinics beyond this week have been canceled, and the remaining ones are likely to be very crowded.

Before going, call first to be sure the clinic is still scheduled. (Not everyone has updated their Web sites.)

What's the latest information on clinics that have been canceled?

As of Friday, Maxim Health Systems planned to continue holding public clinics through this week at pharmacies and grocery stores, including Giant, Shoppers Food Warehouse, Eckerd, Costco (for members only) and Rite-Aid. Call stores for a schedule or go to www.findaflushot.com and enter your Zip code to find a nearby clinic.

After Oct. 16, Maxim will use any remaining vaccine exclusively at assisted-living centers and similar locations, according to company spokesman Wright. All Maxim's corporate flu clinics have been canceled.

Inova HealthSource has canceled all community and workplace clinics. When Inova Health System's vaccination plan for high-risk persons has been finalized, information will be posted on the Inova Web site (www.inova.com) and the Fight the Flu hot line at 877-895-5284.

CVS announced last week that all flu clinics at its stores have been canceled.

MedStar expects to run only 10 of the 265 clinics it had scheduled, including a few this week at public libraries in Prince George's County for high-risk low-income children and adolescents ages 9 to 17, sponsored by a United Way grant. Children must be accompanied by a parent, who must have proof of residency in Prince George's County. Call MedStar at 800-862-2166.

How do I know the shot I'm getting isn't contaminated, like the ones whose shipment was halted?

All vaccine that's been distributed was produced by Aventis Pasteur, and there is no fear of contamination in their lots.

Suppose I'm not high-risk. What are my options?

Basically, four: If you're willing to flout public health urgings, ask your doctor; some private physicians and pediatricians are giving shots to patients outside high-risk groups. Otherwise, try FluMist, consider an antiviral drug or go without.

What do I need to know about FluMist?

According to the Mayo Clinic Web site, studies have shown FluMist to be 86 percent to 97 percent effective, while flu shots are generally 70 percent to 90 percent effective. However, while flu shots are made from killed viruses, FluMist is made from live, weakened viruses, so it should not be taken by people in high-risk groups. The CDC does encourage healthy people between ages 5 and 49 and who are not pregnant to use FluMist. Children under 9 years old who have never had FluMist need to receive two doses the first year, just as with the flu shot.

Health care workers may be treated with the spray as long as they don't care for "severely immunocompromised patients in special care units," according to a CDC press release.

Because the viruses in the nasal-spray vaccine are weakened, the CDC says it won't cause severe flu symptoms. The most common side effects are runny nose, headache, sore throat or cough.

As of Thursday, MedImmune had 1.1 million doses of FluMist ready to ship. All health care providers with pending orders for FluMist should receive their full orders, said company spokeswoman Clarencia Stephen, so check with your doctors and pharmacies. Giant expects to offer FluMist to healthy adults over 18 at its Virginia locations in a couple weeks, but clinics had not been scheduled as of last week. Check with your local Giant or on www.giantfood.com. The FluMist, which will be administered by trained pharmacists, will cost $30 this year -- half last year's price, according to Giant spokesman Jamie Miller.

MedImmune is talking with the CDC about trying to produce more nasal vaccine for this flu season, but the most it might be able to produce would be 2 million doses total, according to Stephen. Ironically, the company produced more than 4 million doses of FluMist last year, but sold only a fraction of that.

How about antiviral drugs?

Three prescription antiviral drugs (amantadine, rimantadine and oseltamivir, sold as Symmetrel, Flumadine and Tamiflu, respectively) are approved for preventing flu, according to the CDC. Usually, these drugs are used to control flu outbreaks in institutions where many people at high risk for complications from flu are in close contact with each other, such as in nursing homes or hospital wards. Side effects in some cases can be nasty, ranging from nervousness and nausea to hallucinations and seizures.

Those same drugs, plus a fourth (zanamavir, sold under the brand name Relenza), are also approved for treating flu. They'll only work, though, if treatment begins within two days of the first symptoms. They'll only shorten the time you spend sick by one to two days, although they may also make you less contagious. Because these drugs vary greatly in who can take them and what side effects they'll produce, you need to discuss with your doctor which, if any, might make sense for you.

Sounds nasty. But if I skip the nasal vaccine and the drugs, how can I protect myself?

You probably know the drill. But here are the CDC's recommendations:

* Avoid close contact with people who are sick. When you are sick, keep your distance from others to protect them, too.

* Stay home when you are sick. Work, school and errands can wait. The CDC says adults may be able to infect others beginning one day before getting symptoms and up to seven days after getting sick. (Bosses, if you don't want an epidemic in the office, tell your sick employees to stay home! Cover your mouth and nose with a tissue when coughing or sneezing, then put the tissue in the waste basket. If you don't have a tissue, cough or sneeze into your upper sleeve, not into your bare hands.

* Clean your hands. Washing your hands often with soap and water or an alcohol-based hand cleaner will help protect you from others' germs, and others from your germs.

* Avoid touching your eyes, nose or mouth. Germs are often spread when a person touches something that is contaminated with germs and then touches his or her eyes, nose or mouth.

And if I get the flu anyway?

Most healthy people will suffer no more than a week or two of fever, cough and aches. The advice from the CDC is probably the same as you'd get from Mom: Rest. Drink plenty of fluids. Avoid alcohol and tobacco. Take medication to relieve symptoms (but never give aspirin to children or teens who have flu-like symptoms -- particularly fever -- without first consulting your doctor. Acetaminophen, such as Tylenol, is okay). See a doctor, advises the Food and Drug Administration, if symptoms worsen or last a long time or if after feeling a little better, you develop new symptoms such as nausea, vomiting, high fever, chills, chest pain or coughing with thick, yellow-green mucus. These can be signs of pneumonia. If a child or high-risk adult gets the flu, call a doctor immediately.

Is there any chance the flu shot supply will increase?

More will be distributed -- but no one knows just where it will go, yet. As of last week, Aventis Pasteur had distributed only 30 million of its 54 million doses of Fluzone. While all but 2 million of the balance had been pre-sold, Aventis and the purchasers are conferring with the CDC about how to make sure the vaccine gets to patients with the greatest need.


Lisa Barrett Mann wrote recently for the Health section about efforts to curb multiple births.

Syringes are loaded with flu vaccine at a Chiron plant. A halt in shipment last week cut U.S. vaccine supplies in half. A doctor administers a dose of intranasal FluMist to a young patient. High-risk patients can't use the nasal spray as an immunization alternative because it contains live virus.