'Universal' flu vaccine could mean single shot every 10 years

(USA TODAY) -- Today's flu shots aren't perfect -- but a "universal" flu vaccine that works better and is longer lasting may not be far off, say health experts.

In the midst of an early flu season, health officials are urging unvaccinated people to still get a flu shot as the best step they can take to protect themselves and their families.

The Centers for Disease Control and Prevention said Friday that flu vaccines are about 62 percent effective. In the past, it said 70 percent to 90 percent effective.

In public health circles, "there is a growing consensus ... that we need better influenza vaccines," says Michael Osterholm, director of the Center for Infectious Disease Research and Policy. "We're operating largely in the 1950s for our flu technology."

He published an influential analysis in The Lancet last year showing flu shots are less effective than commonly reported. For kids and people over 65, there are no rigorous data showing their efficacy at all. But the intranasal flu vaccine (FluMist) protects 83 percent of kids under 8, he found. There is mixed evidence on how well it protects adults over 60, and little evidence on effect in people 8 to 59.

In general, "the flu vaccine is a good vaccine, but not a great vaccine," says William Schaffner, a professor at Vanderbilt University School of Medicine.

Osterholm says he strongly believes people should get yearly flu vaccines, given their good safety record. And he says "moderate" protection is better than none at all.

But drug companies have felt little pressure to make truly "game-changing" vaccines because experts and the public believe current shots are adequate. "The No. 1 deterrent to getting new flu vaccines is the perception that the current ones are good enough," says Osterholm, also a professor at the University of Minnesota School of Public Health.

Today's flu shot, he says, doesn't have much power to produce true "herd immunity," achieved when enough people are immunized that the community's viral load drops, protecting even the unvaccinated.

"The goal is to create a vaccine that you don't have to give every year that works better," says Joseph Bresee, chief of the CDC's epidemiology and prevention branch in its influenza division. "There's a lot of research going on toward improving vaccines."

Today, people need a flu shot every year because the virus is constantly changing. Virologists try to predict which strains will be in circulation, using those in the vaccine.

A "game-changing" vaccine would be very different, producing immunity by including parts of the flu virus that don't change from year to year, and which are common among many strains of virus, Osterholm says. These should protect people for a decade or more, stimulating the immune system to recognize viruses it hasn't encountered for a long time.

In a 2011 interview with USA TODAY, National Institutes of Health director Francis Collins said he was "guardedly optimistic" that a "universal" flu shot could be developed within about five years.

One such vaccine is being tested in a small preliminary U.S. study. But the USA should be doing more, Osterholm says. Developing a next-generation vaccine could take 15 years and cost over $1 billion, he estimates.

But Schaffner says significant improvements are already being made.

Next year's flu shots should provide slightly broader protection. The FluMist nasal spray will protect against four viral strains, instead of three. Manufacturers of flu shots are also working to include four strains.

Also, the Food and Drug Administration in November approved the first flu vaccine made in cell cultures, rather than chicken eggs. The vaccine, Flucelvax, made by Novartis, is approved only for adults.

The USA's current system -- a six- to nine-month process that relies on fertilized chicken eggs to grow viruses -- is "archaic," says Robert Glatter, an emergency medicine physician at Lenox Hill Hospital in New York.

Many European countries already use cell culture techniques, which allow companies to produce vaccine far more quickly, Osterholm says, though it is no more effective.

Glatter says companies face significant obstacles in developing innovative flu vaccines, which must undergo rigorous safety tests. They may see little point in developing a universal vaccine, he adds. "If you get a mega-vaccine once every 10 years, the flu vaccine market would essentially be down-regulated, with less financial market incentive."

Yet Glatter says the H1N1 pandemic flu in 2009 suggests that the human body is capable of producing extremely long-term immunity from influenza. Senior citizens had relatively low rates of infection, likely because they were exposed to a similar virus in the 1930s and 1940s, he says.

"The goal is to make a vaccine that can confer such long-term immunity," Glatter says. "Such a feat would be a real breakthrough."