Experts Say Flu
Growing Deadlier
Jeremy Manier
Chicago Tribune Staff Writer,2669,ART-35761,FF.html
Last winter's flu season killed thousands more people in the U.S. than usual, federal epidemiologists said Thursday, raising the stakes for several new kinds of flu treatments expected to hit the market in the next few months.
Although precise numbers have not been tabulated, officials from the Centers for Disease Control and Prevention said at a Washington, D.C., news conference Thursday that last season's flu deaths easily surpassed the yearly average of 20,000 fatalities nationwide, out of 20 million estimated cases overall. They trace the causes to everything from low vaccination rates in minority communities to unexpected outbreaks on cruise ships in Alaska the past two years.
"One of the most important factors is that a lot of serious complications and deaths happen among the elderly, and that segment of the population has increased tremendously in recent years," said Dr. Keiji Fukuda, chief of influenza epidemiology at the CDC.
Such dangers have set off an intense race among drugmakers to bring the next generation of flu vaccines and remedies to market, as the traditional window for flu vaccination opens this month.
Already this year the Food and Drug Administration has approved Relenza, an inhaler made by Glaxo-Wellcome that prevents a flu virus from making copies of itself. Regulators are reviewing Hoffman-LaRoche's oseltamivir, which works on the same principle. Both drugs can reduce the disease's severity and duration by up to 30 percent and may prevent some people from getting infected, according to studies.
Although neither Relenza nor oseltamivir, also known as Tamiflu, is intended to replace flu shots, officials at the biotech company Aviron expect to submit a radical new vaccine called FluMist for federal approval later this year. That drug would be the first flu vaccine administered as a nasal spray.
"That could bring the vaccine to groups that have not been vaccinated before," Fukuda said. "For children especially, the idea of being able to get vaccinated without a needle is nice."
The CDC is considering recommending that all adults over 50 and all preschool children get annual flu shots. The current recommendations cover only adults over 65 and people with weakened immune systems.
One of the main uses of therapies such as Relenza and Tamiflu may be for people who know they've been exposed to the virus, or who wait too long to get their flu shots, experts say. The drugs start to fight the virus right away unlike vaccines, which take at least two weeks to build up antibodies that ward off infection.
To exploit the special benefits of antiviral therapies, the makers of both drugs are planning unprecedented marketing blitzes that will target specific cities as health officials detect outbreaks there.
"We want to make sure we're giving this to people who really need it," said Charles Alfaro, director of public affairs at Hoffman-LaRoche. "We've found that doctors are better at diagnosing the disease when they know flu is in a given area."
The companies' first task will be to persuade consumers they're better off taking sophisticated antiviral medication than taking cheaper over-the-counter drugs, said Dr. Frederick Hayden, a clinical virologist at the University of Virginia who has led research on both drugs.
"People tend to tough it out," Hayden said. "They expect to get better after a few days. For the new drugs to work, we'll have to see a shift in how patients seek care."
Yet widespread advertising could flood emergency rooms unnecessarily with people who are suffering from ordinary cold symptoms, said Dr. John Flaherty, an infectious disease specialist at the University of Chicago.
"It will be interesting to see how many people come in because of cold symptoms and then insist on getting the new drugs," Flaherty said.
The companies' pitches to doctors will include warnings about the deadly potential of the seemingly innocuous flu virus, which killed an estimated 20 million people worldwide in a 1918-1919 outbreak.
Until this year, the only options for fighting influenza infections were the drugs amantadine and rimantadine, which fight just one strain of the virus and can have serious side effects such as depression or seizures. Both drugs work by keeping the virus from releasing its genetic material inside human cells and using them as a factory to churn out more copies of itself.
The newer medications, in contrast, are called "plug drugs" because they clog a chemical site on the virus surface--the enzyme neuraminidase--that influenza needs to emerge from one infected cell and spread to others.
Hayden has found that this approach can fight off both the A and B flu strains with few side effects, and may also keep the virus from getting an initial foothold in the mucus lining of the respiratory tract. His most recent results, for the Tamiflu pill, were published Wednesday in the Journal of the American Medical Association.
In the course of designing such finely targeted drugs, researchers have amassed detailed molecular maps of the virus surface that help explain why some flu varieties are so deadly.
The latest such outbreak happened in Hong Kong in 1997, when a strain of "bird flu" infected 18 people and killed six, raising the concern of health officials worldwide before the virus disappeared as mysteriously as it had appeared.
Researchers found that, unlike most flu viruses that can infect only the respiratory tract, the Hong Kong strain was unusually deadly because its surface chemistry allowed it to damage many different types of cells.
"That virus had the ability to go into the bloodstream and infect other parts of the body," said Robert Lamb, a professor of biochemistry and an influenza expert at Northwestern University.
Having antiviral drugs for flu may be essential if the next lethal strain begins to spread before scientists can develop and distribute a vaccine, experts say.
One obstacle to the new therapies will be cost. A five-day course of Relenza runs about $40, at least four times the expense of over-the-counter drugs or flu shots.
In a preview of concerns that likely will drive U.S. managed-care insurers' response to the new drugs, Glaxo-Wellcome has estimated that introducing Relenza would cost the British National Health Service up to $25 million this flu season. Glaxo-Wellcome says the expense has British officials considering barring government doctors from prescribing the drug, a move many pharmaceutical companies say would stifle the development of such therapies.