Lack of vaccine raises fear of potential bird flu pandemic
WASHINGTON — As concerns mount that avian flu could trigger a worldwide outbreak, scientists and public health advocates are afraid an effective vaccine won't be developed and distributed in time.
Just this week, the World Health Organization reported that the virus, which has been confined to Asia, appears to be mutating so that human-to-human infections are possible.
So far, humans have caught the avian flu from birds only.
If human-to-human transmission occurs, experts fear that a global health crisis could be in the making. “It will be the next pandemic,” said James Campbell, an infectious-disease specialist at the University of Maryland School of Medicine.
What makes bird flu particularly dangerous is that humans have no immunity yet. It is a new flu strain, and humans have not developed antibodies to fight it.
Experts worry that an avian flu outbreak could rival or even surpass the 1918 Spanish flu outbreak that killed 50 million people, including 550,000 in the United States.
The National Institutes of Health fast-tracked a series of clinical trials on a new vaccine this spring at research centers in Los Angeles, Rochester, N.Y., and Baltimore.
Campbell, director of the Baltimore trials, says his team thinks it is close — but warns that production of a vaccine would take a minimum of six months.
But even that's not assured, given the problems the United States faced last fall when the overseas manufacturing plant for the normal annual flu vaccine had to shut down because of contamination problems.
“We're so far behind at every level,” said Kim Elliott, deputy director of the Trust for America's Health, a public health interest group. “As of today, there is no known effective vaccine against this particular strain. While scientists are madly scrambling how to develop it, it hasn't been done yet.”
Given the circumstances, several governments around the world have been trying to stockpile Tamiflu, an antiviral medicine that scientists say could treat the symptoms of avian flu, though not necessarily prevent it, as a vaccine could. But the U.S. supply is low.
Tamiflu must be taken twice a day for five days. Washington has 2.3 million courses of treatment in reserve. It would need about 74 million, based on the WHO's estimate that a pandemic outbreak could affect 25 percent of a country's population.
Great Britain has met that, ordering nearly 15 million treatments. Canada, France and several other countries have also placed large orders to boost supplies.
Britain is also further along with its emergency planning, having prioritized who would be vaccinated and who would receive antiviral drugs.
A spokesman for the National Vaccine Program Office of the U.S. Department of Health and Human Services, which is spearheading the development of the government's response plan, could not be reached for comment.
Democratic Sen. Barack Obama of Illinois introduced a bill last month requiring the U.S. government to start stockpiling Tamiflu. Roche, a Swiss pharmaceutical company and the sole manufacturer of Tamiflu, also known as oseltamivir, has stepped up production and plans to open a new plant in the United States.
Still, Rex Archer, director of the Kansas City Health Department, said he decided not to purchase Tamiflu for city employees — to ensure that local services would continue through an outbreak — because the city would have needed 1.7 million doses for them and their families.
Archer said the drug poses a “policy dilemma” because if it is not used before its five-year shelf life expires, “you've spent so many dollars and then threw it away. That's just reality.”
Other concerns include what would happen if hospitals were overwhelmed or if health-care workers were infected. And how do authorities ensure that food, water and other supplies are available?
In addition, experts said that ventilators would be in short supply and that there were not enough protective face masks.
If the bird flu virus mutates, “we are facing an unprecedented outbreak,” said Linda Lambert, a microbiologist and chief of the respiratory disease branch at the National Institute of Allergy and Infectious Diseases.
“Nobody can tell. But we're having a higher level of worry about things than I think people have ever had before because we're dealing with something in a magnitude we never have had to before.”
Known as H5N1, avian flu showed up in 1997 in Hong Kong markets where live chickens and other poultry were available. Six persons died, and authorities quickly destroyed 1.5 million birds. But the virus has since spread to 10 Asian countries, wiping out millions of birds and putting scientists and public health officials on high alert.
Lambert said the Hong Kong outbreak was a “watershed” because a bird virus normally first infects a pig before it passes on to a human. That is because a pig has cells similar to both.
So far the flu, a respiratory infection, has infected humans only in small numbers: Since December 2003, 97 cases have been reported in Vietnam, Cambodia and Thailand; 53 victims have died. But new cases of bird-to-human transmissions are reported “almost weekly,” Julie Gerberding, director of the Centers for Disease Control and Prevention, told Congress last month
And now the virus is like a computer, Lambert said, running through reams of data trying to break a code until it hits on the right sequence — “the combination that will allow it to spread person to person.”
Viruses can often mutate to human-to-human transmission. The AIDS virus is thought to have moved from other primates to humans before it mutated and became transmissible among humans.
If the avian flu mutation occurs, scientists say, the ease of modern travel could make it next to impossible to control the virus, enabling it to swiftly span the globe.
During a normal annual flu season, the death toll in this country is 30,000 to 50,000 people. Experts warn, however, that bird flu could spawn a pandemic worse than the 1918 Spanish flu outbreak.
In a recent issue of the New England Journal of Medicine, infectious-disease expert Michael Osterholm of the University of Minnesota said 1.7 million deaths could occur in this country and up to 360 million worldwide.
With concern rising, President Bush signed an executive order last month that would allow authorities to quarantine people in the event of a pandemic.
Meanwhile, a draft of the federal government's Pandemic Influenza Preparedness and Response Plan warns of travel advisories, checkpoints, school closings and the restricting of public gatherings. Some experts have said borders might have to be closed.
Aaron Winslow, emergency response coordinator for Missouri's Division of Environmental Health and Communicable Disease Prevention, said that improvements in disaster planning since the Sept. 11, 2001, terrorist attacks had aided preparations for a flu pandemic.
But if an outbreak occurs, said Georges Benjamin, director of the American Public Health Association, “it will be here before we know it, before we can actually do a lot of preventative things.”