As reported by the New Haven Register, May 8, 2005.
Warning: Avian Flu Pandemic Looming
By Abram Katz
A global wave of death and disease may be gathering in Asia, and
America’s only defense is 2.3 million doses of anti-influenza
Although a flu pandemic is impossible to predict, the avian influenza virus festering in several Asian countries shows ominous warning signs, doctors, epidemiologists and other experts warn.
"Many people are worried about a pandemic and we would not have immunity. This is one of those situations in which it’s better to be safe than sorry," said Dr. Michael H. Merson, professor of public health and former dean of epidemiology and public health at the Yale School of Medicine.
"The bird flu has all the potential of an epidemic," he said.
The H5N1 avian strain has not been seen in 150 years, meaning no one has any residual resistance.
And the virus kills seven out of 10 people who become infected.
Flu viruses almost always appear first in birds, and then mutate into forms that can infect and travel in humans, Merson said. Whether H5N1 will follow this path is unknown.
The United States, Canada, France, Germany, Japan and other countries are taking the threat seriously enough to make H5N1 vaccines and stockpile millions of doses of anti-viral drugs.
Unlike the catastrophic "Spanish flu" that killed 20 million people worldwide in 1918-19, "we’re getting a warning with this one," Merson said.
"We need to respond with all we have," he said.
All the United States has is an experimental H5N1 vaccine that was scheduled to start clinical testing this month and 2 million doses of anti-viral drugs.
Britain, in contrast, has procured 15 million doses, enough to treat about a quarter of its population.
About 75 million doses would be necessary to reach 25 percent of the U.S. population, according to the Trust for America’s Health, a nonprofit, nonpartisan medical think tank in Washington.
"We are likely to be hit by a pandemic. Most scientists believe it’s a question of when, not if," said Dr. Shelley Hearne, executive director of TFAH.
Meanwhile, the World Health Organization and the U.S. Centers for Disease Control and Prevention selected the two A-strains and one B-strain to include in this winter’s flu vaccine.
However, the 2005-06 vaccine supply is already in question and the CDC last month advised early buyers to plan on reserving available vaccine for those most at risk.
As bad as the predominant strains are, the avian flu is far more worrisome.
Right now the virus can only spread from bird or animal to human. The 70 known cases, which have left 50 dead, all had close contact with infected fowl.
But the longer the virus lingers, the greater the risk that it will swap genetic material with a flu virus that is transmissible by people, Merson said.
A person with "regular" flu who becomes infected with avian flu could provide the living test tube in which the transfer could take place.
"Then it could be a plane ride away," Hearne said.
After that happens, the new virulent strain could sweep around the world, said Dr. John D. Shanley, head of infectious diseases at the University of Connecticut Health Center.
"All cases to date are bird-to-human transmission. The virus would have to change receptors to infect humans," Shanley said.
"The flu is very adaptive. This is a highly pathogenic virus lethal to chickens, with a 70 percent mortality rate in humans. If it makes the final adaptation there’s a pandemic," he said.
Shanley and other specialists said they are comparatively unconcerned about an ongoing outbreak of Marburg virus in Angola.
Marburg, a relative of Ebola, is so "hot" that it kills victims before they can disperse the virus, he said.
Influenza poses a greater geographic threat. Flu sweeps around the world every 10 to 40 years and right now the planet is overdue.
"Does Marburg keep me up at night now?" Hearne said. "No. I’m more concerned about the flu virus."
Dr. Zane Saul, chief of infectious diseases at Bridgeport Hospital, said H5N1 could be serious, but should not be over-estimated.
The virus could mutate into a humanly transmissible form, he said. "The potential is there, but it’s not likely." The mutation that confers human transmissibility could also reduce the virus’ virulence, he said.
"Patterns suggest that a pandemic could be possible. Viruses mutate and increase transmissibility. Now, hopefully, we could treat flu patients in better ways," he said.
The victims of 1918, most in the prime of life, frequently progressed from full health to death in 24 hours. Their lungs filled with fluid and they suffocated.
About 500,000 Americans died, roughly 10 times the number of U.S. soldiers killed in World War I.
Antibiotics for secondary infections, the drug zanamivir (Tamiflu), and other advances in medical technology could probably reduce pandemic casualties substantially, Saul said.
Even with the best medical help, influenza kills about 30,000 people in the U.S. annually. New vaccines are required every year because influenza viruses are incredibly malleable.
Flu viruses are classified according to two surface proteins, hemagglutinin (H) and neuraminidaseinase (N).
They are involved in entering and then bursting out of unfortunate host cells.
There are 15 known types of H and nine types of N. Genes for these and other proteins are contained on eight strands of RNA in the viral core.
When two A-type viruses infect the same cell, their RNA can mix, producing a new strain.
Public health officials believe that H1N1 and H3N2 will be circulating in the Northern Hemisphere this winter.
Last year, the United States lost half of its promised flu vaccine when a British manufacturer’s plant was shut down over health concerns.
Remaining stocks were allocated to the elderly, the very young and people with chronic illnesses.
Early in April, the CDC issued a report on "Influenza Vaccine Prebooking and Distribution Strategies for the 2005-06 Influenza Season."
Vaccine shortages are apparently already anticipated.
"The supply of influenza vaccine ... for the 2005-06 influenza season appears sufficient to meet the historical demand for vaccine by persons in all the priority groups (of 2004)," the CDC states.
If additional vaccine becomes available, other segments of the population can also be inoculated, according to the CDC.
"Our smartest defense is a well-prepared health system," Hearne said. "We still have a long way to go."
The U.S. reliance on a limited number of flu vaccine manufacturers leaves the country vulnerable to both emerging viruses and bioterrorism," she said.
"It’s much more lucrative to make Viagra than vaccine. That’s a public health tragedy," she said.