Those 18 to 64 who are squeamish about shots can opt for a vaccine that uses a tiny needle to deliver immune-boosting vaccine into the skin, rather than into the muscle like the standard shot. Also, people 65 and older can get a high-dose version, which should give better protection against the flu.
Influenza specialist Kristin Nichol, M.D., professor of medicine at the University of Minnesota Medical School, says both new flu shots may come to occupy a "special niche" in the arsenal against influenza. "It's very exciting to have these new vaccines available," she says.
As for the nasal spray flu vaccine that was first introduced in 2003, it is a weakened live vaccine recommended only for those ages 2 to 49; those 50 and older should not get it.
Although an annual flu shot for older people has long been a mainstay of U.S. public health policy, the last several years have brought increasing debate among experts about just how effective the vaccine is in older people.
Research has suggested that getting the shot decreases an older person's chances of being hospitalized for flu or pneumonia, and of dying. But studies also make clear that the vaccine doesn't always protect older men and women against the flu.
That's partly because the vaccine works by stimulating the body's own immune reaction — and the aging immune system tends to mount a weaker protective response.
High dose may give more protection
Fluzone High-Dose, launched during last year's flu season, is meant to address this problem. The vaccine contains four times the immune-triggering viral proteins as the regular shot. In early studies, it triggered a much stronger immune response in older people than the standard dose.
The U.S. Centers for Disease Control and Prevention (CDC) has not recommended the high-dose shot over the standard vaccine, preferring to wait for the results of research looking at whether greater antibody response translates into fewer people getting sick with the flu.
But the higher dose is likely to impart stronger protection, says William Schaffner, M.D., president of the National Foundation for Infectious Diseases and a preventive medicine specialist at Vanderbilt University. It also poses no special safety concerns, although side effects like soreness at the injection site are more pronounced. "Given the choice," he says, "of course I would recommend the high-dose version."
At a list price of $25, Fluzone High-Dose is costlier than the standard vaccine, which goes for around $11. Both, however, are covered by Medicare part B with no copayment. There are ample supplies of the vaccines this year, according to the CDC.
Afraid of needles?
The main selling point of Fluzone Intradermal (listed at about $15.50) is that its very short, slender needle merely pricks the skin — a painless, simple-to-administer "micro-injection" that maker Sanofi Pasteur hopes will find widespread acceptance and help increase flu vaccination rates.
Because the injection goes into the skin, an area rich with cells that play an important role in immune response, it produces about the same antibody response as the standard shot, but with 40 percent less active ingredient. That could prove a boon in any year when vaccine is in short supply.
The CDC recommends that everyone age 6 months and older get a yearly flu vaccine, except in a very few cases like a severe allergy to eggs. This program for near-universal vaccination was introduced last flu season, when manufacturers shipped a record number of doses to U.S. pharmacies and doctors' offices.
Even though the flu season doesn't usually peak until late January or early February, people should get the 2011-2012 vaccine as soon as it's available in their location, says CDC spokesperson Jeff Dimond.
The shot provides immunity against the same three strains of influenza as last year's vaccine. Public health authorities predict these strains, including the 2009 pandemic "swine" flu strain, will predominate again this flu season. CDC officials say that because vaccine-induced immunity wanes over the course of a year, those vaccinated last year need to get another flu shot this season.
Getting vaccinated is the cornerstone of flu prevention, says Nichol, but it's not perfect and won't protect everyone equally.
For those who may not get complete immunity from the vaccine, it's key for other people in the community — coworkers, grandchildren, health care personnel — to be vaccinated also, both for their own protection and to prevent the spread of flu germs. And the old advice remains some of the best: "In addition to getting vaccinated," says Nichol, "wash your hands frequently, cover your cough, stay home when you're sick and avoid exposure to others who are sick."
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Katharine Greider lives in New York and writes about health and health policy issues.