Drugs for bird flu pandemic limited

Prescription flu drugs could provide lifesaving early protection against bird flu if the virus disastrously mutates into a worldwide pandemic, but experts warn that supplies will quickly run out unless governments stockpile the medicines.

Early talks are going on between the U.S. government and one maker about providing a large quantity for use in a pandemic, but at best the medicine is still months away.

If enough was available, the drugs could help buy time until a vaccine is developed to stop the flu's spread.

Experts say the flu drugs could shorten illness and prevent lethal complications for flu victims -- as well as keep healthy people from catching it, especially health-care workers.

Doctors say only one brand, Tamiflu, is practical for large-scale stockpiling, but so far no government has bought the big amounts needed for a pandemic. For now, worldwide supplies are skimpy, because the drugs are not widely used to treat ordinary flu.

"This needs to be in the national stockpile, just as much as Cipro and smallpox vaccine," says Dr. Arnold Monto, a flu expert at the University of Michigan. A bird flu pandemic "could have as much of an impact as a manmade terrorist attack."

The U.S. government has already ordered an extra supply of Tamiflu to help deal with the current flu season, although the exact amount is classified. Much more would be needed for a pandemic.

Roche's Tamiflu, a pill introduced in 1999, is one of two drugs called neuraminidase inhibitors that appear to be effective against all kinds of flu, including the bird flu circulating in Asia. The other, GlaxoSmithKline's Relenza, requires an inhaler and is rarely used. It is not considered suitable for stockpiling.

Roche makes only as much as is needed for a typical flu season and does not stockpile the drug for an emergency. "If there was a large outbreak like a pandemic, it would take at least several months to produce additional product on top of what's already available," says Terence Hurley, a Roche spokesman.

So far, he said, the company has received no orders for stockpiling large amounts. However, the company is in "preliminary discussions" with the U.S. Department of Health and Human Services. The World Health Organization is also working on stockpiling plans with several European countries.

Tamiflu and Relenza are much more expensive than an older and more widely available category of flu drugs called M2 inhibitors. These include the generic medicines rimantadine and amantadine.

When the current variety of bird flu first spread from chickens to people in Hong Kong in 1997, it could be treated with the M2 drugs. But it has since mutated and become resistant to those medicines, a discovery that Dr. Frederick Hayden of the University of Virginia called "very disquieting."

"That means that a whole class of drugs really would not be useful for treatment or protection," Hayden said.

Just how the flu drugs might be used has been widely discussed and debated among flu experts, who agree they could be especially critical in the early months of an outbreak, assuming enough was available.

"I think it would definitely have a major role in the first wave of any new pandemic strain and would perhaps provide time for the development of a vaccine," says Dr. Paul Glezen of Baylor College of Medicine in Houston.

A flu vaccine takes at least six months to develop and manufacture in the best of circumstances. A bird flu shot is likely to be even more difficult, because it requires genetic engineering techniques that have never been used in human vaccines.

Meanwhile, a bird flu virus could spread around the world in weeks and would be very difficult to contain by isolating victims -- as was done with SARS -- since flu is more contagious.

For now, bird flu is widespread among poultry in many Asian countries. A handful of cases have been documented in people, but there is no sign of person-to-person spread. The fear is that someone already infected with the human flu will also catch bird flu. The two viruses could swap genes inside the victim's body, producing a very contagious new virus for which people have little or no immunity.

Experts say supply is the single biggest concern about flu drugs. "If there really was an explosive worldwide epidemic, we would have shortages of the drugs," says Dr. John Treanor of the University of Rochester.

If taken by healthy people, Tamiflu could probably significantly reduce the chance of catching the flu. People would need to take it daily for at least six weeks, until the wave of disease passed, and not even a huge stockpile would allow for that.

However, some experts say it might make sense to give the drug to protect essential personnel, such as hospital workers, ambulance crews, firefighters and police.

The drug's main benefit, though, would be in treating the sick. Some propose giving it to everyone who gets sick in the first days of an outbreak. That would make them less likely to infect others, and might slow the epidemic.

Others recommend limiting the drugs to those most likely to die from the flu, such as the elderly. "That assumes that we are not all at the same risk," says Monto.

If taken soon after symptoms start, Tamiflu can shorten a bout of ordinary flu by several days, and people often start feeling better within hours. How well it would work against a mutant bird flu is unknown.

No one knows how many would get sick in a bird flu pandemic, or even whether a new virus would truly spread as easily in humans as it does in birds. However, experts generally estimate that 30 percent to 40 percent of the population gets sick in a flu pandemic.

In the worst pandemic on record, the 1918-19 Spanish flu, an estimated 40 million to 50 million died. The world population is almost four times larger now.

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EDITOR'S NOTE: Medical Editor Daniel Q. Haney is a special correspondent for The Associated Press.