Since late 2003, 79 people in Vietnam, Cambodia and Thailand have contracted avian influenza from infected poultry flocks. Forty-nine people have died. The outbreak has prompted the destruction of millions of potentially infected chickens.
Public health officials say there is a risk of a worldwide pandemic if the virus mutates and is more easily passed from person to person. Conventional strains of influenza kill between 250,000 and 500,000 people a year. The Avian flu could be much worse.
To address this looming threat, research sponsored by the National Institutes of Health in the United States has focused on the safety and effectiveness of an avian flu vaccine.
Robin Perry, 33, is on the front line in the fight against avian influenza. When the research associate rolled up her sleeve for a dose of the experimental H-5-N-1 vaccine at the University of Maryland Medical Center this week, she was reminded of another public health threat. "I thought about the SARS outbreak," she says, "and I thought that we were lucky that we didn't have anything over here in the United States." But Ms. Perry realizes there is nothing to prevent the avian flu from coming to the U.S. "I want to be protected," she says, "and I want what I do to help others be protected."
Ms. Perry is among 450 volunteers at three U.S. test sites. James Campbell is principal investigator for the vaccine trials at the University of Maryland School of Medicine. He says the goal is twofold: "Is the vaccine safe? And do volunteers mount an immune response that might protect them against avian influenza?"
The trials will closely monitor volunteers. "After we vaccinate," Dr. Campbell says, "we
watch them in the clinic for a short period of time to make sure that they don't have any immediate reactions. Then they are sent home with a 1 week diary in which they record any symptoms they may have in the week following vaccination. And we also draw their blood before and after vaccination to make sure the vaccine doesn't affect things like their liver, their kidneys, their bone marrow, those sorts of things."
In terms of immune response, Dr. Campbell says, blood is drawn before vaccination and multiple times after vaccination and analyzed in the laboratory to see whether or not volunteers have mounted an immune response.
Since the vaccine is made with an inactivated or killed avian influenza virus, volunteers are not at risk of contracting the disease.
The United States has already stockpiled 2 million doses of H-5-N-1. James Campbell says it is hard to predict when or how the virus mutates -- or as scientists like to say drifts. But information from trials helps to answer a basic question: "Can we make an avian influenza vaccine by this method and get good immune responses and have safety in healthy adults?" Dr. Campbell asks, and adds, "Even if there were drift and we needed to use a different seed virus, the same vaccine could be made by using a different virus, just like we do each year with routine influenza. It is the same process. We would expect the same safety and the same immune response."
Anthony Fauci heads the National Institute of Allergy and Infectious Diseases. Speaking at a recent meeting of the American Society for Microbiology, he expressed confidence that research now underway in the United States will help prevent a worldwide pandemic. "If you start seeing pockets of cases," he says, "it is to the benefit of the United States citizens to cut it off in Vietnam or in Thailand or wherever, as opposed to saying, 'No, hands off. We will wait until it comes here.'"
Dr. Fauci emphasized that this was not the policy of the U.S., because no policy has been made. He added, "We are certainly open -- as (are) other developed nations -- to the consideration of sharing this (research) with developing nations that don't have those facilities (to conduct vaccine trials)."
The current trials test the vaccine on healthy adults. Before the end of 2005, the vaccine will also be tested on children and the elderly. In addition to those underway at the University of Maryland, trials will be conducted at the University of California, Los Angeles and the University of Rochester in New York.