Researchers Chasing Elusive Idea Of Single Vaccine For All Types Of Flu

August 17, 2009|By Stephanie Desmon | Stephanie Desmon,

The ever-changing flu virus is slippery, mutating so rapidly that vaccines designed to protect against it shield for a single season, if that long.

But what if a flu shot could be a one-time proposition, maybe a rite of childhood like so many other vaccines? In a year like this with pandemic influenza racing across the globe, officials have been left scrambling to develop a vaccine to guard against this new H1N1 virus, all the while preparing for the complicated annual ritual of giving seasonal flu shots to millions. Fearing such a pandemic, researchers for years have been working to create what is known as a universal flu vaccine, a single inoculation that would defend against severe infection from any type of flu - seasonal or otherwise.

So far, while there has been some progress, no one has succeeded. At least not in humans.

"We cannot protect against pandemics. We cannot make vaccine fast enough" when a new strain appears, said Dr. Hildegund C.J. Ertl, who heads the vaccine center at the Wistar Institute in Philadelphia. "If you have a universal vaccine, you stop worrying about pandemics. A lot of people are trying."

For several reasons, it could be a decade before a vaccine like this hits the market. Researchers still haven't determined whether the approach will work. Meanwhile, any vaccine would need to be championed by a manufacturer, and it could be difficult to find a company willing to take a risk when the vaccines currently on the market do a decent job most of the time.

"We're still pretty far away from any sort of [universal] vaccine," said Dr. Wilbur Chen, a vaccinologist at the University of Maryland's Center for Vaccine Development, where an experimental swine flu shot is being tested now. "We still haven't been able to find the right candidate."

Still, Chen said, developing one would answer many of the limitations of seasonal shots, which must be given again and again: "It would be great if it was like other vaccines where you could give one vaccine or a booster shot every so often and not have to do it every year. ... It's the panacea for what we're doing right now."

While researchers are attacking the universal flu vaccine problem from many directions, the goal is the same: to find a part of this ever-changing virus that doesn't change and take aim at that.

Some researchers are focused on something called the M2 ion channel, which makes up less than 1 percent of the surface of the virus, said Dr. Robert Belshe, who is studying universal flu vaccines as director of St. Louis University's vaccine center. There are just a few copies of this on the surface of the virus, but Belshe said it plays an important regulatory role for the whole virus.

"The virus doesn't function without this ion channel," he said. "If you make antibodies to the ion channel, do the antibodies alter that ion channel and basically plug it up? Does it prevent the disease? Does it slow down the disease?"

In his studies with mice and ferrets, such a vaccine prevents death in the animals, even when they are exposed to lethal doses of flu virus.

"The mice are getting influenza, but they're not getting as sick as they would if they hadn't gotten the vaccine," he said.

A small clinical trial Belshe worked on, designed to determine safety but not effectiveness, proved successful. But what is needed is a large clinical trial, he said, to truly test the promising, though unproven, concept. So far, no such trial is in the works, he said.

Even then, he said, he believes this approach likely will not keep people from getting sick. It would just prevent many of the deaths associated with a severe flu season.

Several leading researchers said that at this point they envision a universal flu vaccine as a supplement to current vaccination, not a replacement for the yearly immunizations. Such a vaccine would be most useful in years like this, when a new pandemic strain appears and begins circulating widely. Such vaccines would also be of use in years when the strains of the flu that end up circulating don't match the strains included in that year's vaccine.

Mismatches are not uncommon. Two years ago, two of the three strains included in the seasonal vaccine had mutated by the time the vaccine was administered, leaving people far less protected from that year's flu bugs. The seasonal flu kills 36,000 Americans a year and sends hundreds of thousands to the hospital.

A universal flu vaccine, on its own, would be cheaper and easier to administer since it wouldn't have to be given every year.

Developing countries can't afford annual vaccination programs. In India, Ertl said, there are no flu vaccines given. They are too costly. Many people in the United States go unvaccinated because it can be a hassle to keep up with the shots each year. About 100 million Americans a year get seasonal flu shots - less than 40 percent of those for whom the shots are recommended.

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