SAN FRANCISCO -- Americans ready to take up arms and noses against the bug that causes the seasonal flu have plenty of ammunition this year. The federal government expects a record amount of flu vaccine to be on hand at clinics, doctors' offices, drugstores and certain retail outlets in the next few months.

About 140 million to 146 million doses will be available through the end of the flu season, according to the Centers for Disease Control and Prevention. Most vaccines are in the form of injectable flu shots, but up to 12 million doses can be applied as a nasal spray in healthy people ages two to 49.

There are six manufacturers for this year's supply and no production bottlenecks reported so far, said Tony Fiore, a medical epidemiologist for the CDC in Atlanta.

"We've been lucky and were able to produce it quite effectively and ship it out in late August," he said.

Consumers who haven't done so yet can get vaccinated right away since the immune response lasts throughout the flu season, Fiore said. Influenza typically doesn't peak until February, but some years it starts early and strong, such as the severe flu season that struck suddenly in October, 2003. Vaccination is available later in the season, but it often pays to act sooner.

"Getting it done earlier is better for two reasons: It means you don't forget and don't find your physician stops vaccinating or doesn't have it," Fiore said. "The other is you never know when we'll have an early season. If you've made the decision to get vaccinated, there's no reason to delay it and risk having, in your particular community, a peak in October."

Each year, influenza sends 200,000 Americans to the hospital and kills 36,000 on average, most of them elderly or with compromised immune systems.

Who should get one

The CDC says anyone who wants to reduce their chances of getting the flu and doesn't have an allergy to chicken eggs can get vaccinated, but certain groups should make sure they don't miss out.

The agency recommends that all children age six months through 18 receive immunizations. The CDC also urges pregnant women, people over 50, residents of long-term-care facilities, those with chronic medical conditions and those in close contact with any of these vulnerable groups to get a vaccine.

"Essentially what they're saying is everybody should get a flu vaccine," said Dr. Paul Glezen, professor of microbiology and pediatrics at Baylor College of Medicine in Houston.

Making the recommendations simpler and urging the vaccination of all kids six months and older is likely to benefit people over 65 as well, he said. "They'll be less likely to be exposed to the virus."

Some parents and health-care providers underestimate how serious flu complications can be for children under five, Fiore said, noting their flu-related hospitalization rates approach those of the elderly.

During the 2006-07 flu season, about one in five children age six months to 23 months were fully vaccinated, according to the CDC. Only 17% of children age two to five had protection.

"The coverage rates for flu vaccine are pretty low in every group that we look at," Fiore said.

For the last decade, the CDC has recommended that pregnant women get vaccinated during flu season. A new study published in the Sept. 17 edition of the New England Journal of Medicine suggests pregnant women who forgo their annual immunization are passing up the chance to protect not only themselves but their babies.

In a study of 340 pregnant women in Bangladesh, flu vaccination reduced by 63% the occurrence of lab-confirmed influenza in infants up to six months of age, the study found. Similarly, it cut the incidence of flu-like respiratory illness with fever in infants by 29% and by 36% in the mothers.

"There's no guarantee, but most years the flu vaccine will prevent most flu, and now we know when you immunize the mother it will immunize the baby," said Dr. Mark Steinhoff, a professor of pediatrics and international health at Johns Hopkins Bloomberg School of Public Health in Baltimore. The flu vaccine isn't approved for children under six months of age.

Women who want to offer their soon-to-be-newborns protection from the flu but are concerned about the possible effects of vaccine preservatives can request a flu vaccine that doesn't contain thimerosal, Steinhoff said.

Sanofi Pasteur, one of the largest suppliers of U.S. flu vaccine, is offering preservative-free vaccines in about a quarter of the 50 million doses it's providing this year, company spokeswoman Donna Cary said.

Questions about effectiveness

Getting a flu vaccine remains the best way to avoid contracting the virus, public-health experts say. It takes about two weeks to develop antibodies that protect against the bug.

Early each year scientists try to determine which three strains of the flu are most likely to circulate later in the year and include them in vaccine production.

The strains chosen for last year's vaccine proved less than an optimal match to the ones that actually ended up proliferating, Fiore said. Preliminary CDC studies estimate it was only 45% effective against last year's dominant strains, he said.

"In a good season we might hope for 60% to 90%" effectiveness, Fiore said. "We lost some degree of effectiveness, but it was by no means futile."

That means people who received a vaccine last year may have gotten less sick than they otherwise would have had they gone without any vaccine protection, he said, possibly resulting in a few days of missed work rather than a doctor's visit or hospital stay.

Flu symptoms can include fever, body aches, headache, tiredness, sore throat, cough and a runny or stuffy nose. Other ways to limit the spread of flu are washing your hands frequently, covering your coughs and sneezes and staying home from work or school when you're sick.

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