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Avian Flu Vaccine Tests Progress in Maryland

Young chickens / Photo by Joe Valbuena, courtesy USDA
Maryland scientists are working on an avian flu vaccine to be used if the virus were to jump from poultry and begin spreading among humans. (Photo by Joe Valbuena, courtesy USDA)

By April Chan
Maryland Newsline
Thursday, Oct. 20, 2005

COLLEGE PARK, Md. - The first phase of a clinical trial on a vaccine designed to combat the avian flu virus is expected to conclude Oct. 31, as officials begin building a defense against a potentially deadly pandemic.

Experts at the University of Maryland School of Medicine in Baltimore were asked to determine what would be optimal and safe dosages of a vaccine produced by pharmaceutical company sanofi pasteur to ensure a person was properly protected from the avian influenza virus.

Sanofi pasteur provided researchers with 8,000 investigational doses of the vaccine that was specifically designed to fight the H5N1 avian flu virus strain, company spokesman John Abrams said.

Maryland Scientists Use Computer Model to Predict How Avian Flu Could Hit U.S.

Maryland Newsline
Thursday, Oct. 20, 2005

COLLEGE PARK, Md. - If the avian flu leads to a worldwide outbreak in which humans begin contracting the disease not from poultry but from each other, how would the United States cope?

That’s the question scientists from Johns Hopkins University and Imperial College in London are asking as they imagine a worst-case scenario in which Americans unwittingly start spreading the disease at an alarming rate.

The scientists are using a computer model they had earlier created to predict a similar epidemic in Thailand where the avian flu has been prevalent, said Derek Cummings, research associate at the Bloomberg School of Public Health at Johns Hopkins.

But the American model looks into what happens after the disease arrives, rather than simply exploring how to contain a small community where it may surface first, Cummings said.

The avian flu strain that looks to be the most likely candidate to cause an outbreak - H5N1 - has not emerged on American soil, he said.

“We're approaching this from the angle that there would be cases globally and ask how mortality might be minimized: What can you do to sort of deal with the incidents so that it doesn't hit all at once?” Cummings said. That would allow time for vaccines to be developed, he said.

Funded by the National Institute of General Medical Sciences, a branch of the National Institutes of Health, the scientists are using U.S. Census Bureau data and making a number of assumptions about U.S. population density, Americans’ travel and work habits and the kind of human interactions that might most easily spread the disease.

“We are trying to get a handle on how far people move spatially in a given day, which would give you an idea of how fast the disease moves,” Cummings said. “And the model also considers domestic air travel and how that spreads disease and what kind of controls could be put in place.”

The scientists are also making educated guesses about the possible impact of “social distancing measures”-- such as staying home from school when a child is sick.

Cummings said the team is considering how American access to avian flu vaccines might serve as extra protection. The U.S. Department of Health and Human Services recently entered into agreements with three pharmaceutical companies to manufacture vaccines meant to specifically fight the avian flu. The University of Maryland School of Medicine in Baltimore is one of three universities testing the first avian flu vaccine produced by sanofi pasteur. The University of Maryland school is completing the first phase of a trial involving 154 Maryland volunteers on Oct. 31.

Cummings said he and his collaborators plan to release details of their American pandemic model in November.

--By April Chan

James Campbell, the principal investigator for the study and assistant professor of pediatrics, said he and his collaborators at the University of Rochester and the University of California in Los Angeles determined that the vaccine should be administered in two doses.

“A single dose of the vaccine did not give people protective levels of antibodies in their blood,” he said.

Four different dose amounts were tested: 7.5, 15, 45 and 90 micrograms, Campbell said. The scientists found that the two largest amounts produced the most significant immune response.

The vaccine appears to be safe, Campbell said, adding that the 154 Maryland volunteers were constantly monitored for red or sore arms or other adverse reactions to the intravenous shots.

“Still, whenever you test a new vaccine, you have to start with the assumption that there might be something that you weren’t expecting but could happen,” he said.

On Oct. 31, the scientists will draw new blood samples from the Maryland volunteers and take a last measure of antibodies in their blood. Those results will be compared to blood drawn before the first vaccine was administered and at two other stages during the study.

Antibodies are what the immune system makes to fight a foreign invader or disease, Campbell said. More antibodies detected in the blood means that the body is developing a better immune response to fight the avian flu.

More Testing Needed

Campbell said he didn’t know when the vaccine would make it on the market. “At this point, it’s hard to predict, but if the need arose, doses will be made,” he said.

According to Oct. 10 estimates from the World Health Organization, 60 people in Asia have died from the H5N1 strain since December 2003, and 117 cases of it have been confirmed.

The Centers for Disease Control says the current risk to Americans is low if an outbreak occurs in Asia but remains mostly confined. There was a brief scare in 2004 when another less harmful strain of the virus was discovered on two Delaware farms. Since 1997, millions of chickens and pigs worldwide have been killed to keep the virus at bay.

If the virus were to mutate and gain the ability to transmit from human to human, which it currently cannot do, containment becomes much more difficult, said Derek Cummings, a research associate at the Johns Hopkins Bloomberg School of Public Health.

Scientists worry that in Asia, where human and poultry contact isn’t very regulated, chances are high that someone will become infected with both a human and an avian flu strain, Cummings said. In that event, the two virus strains could easily exchange genes, and the avian strain would acquire the ability to transmit between humans. If that were to occur, CDC experts estimate that a “medium-level” pandemic could kill 89,000 to 207,000 people and render anywhere from 20 million to 47 million people sick.

Corrections

The first-edition version of this story gave an erroneous estimate on the number of people who could be killed by a "medium-level" pandemic. CDC experts estimate it could kill up to 207,000 people.

The earlier version of these stories also erroneously listed the name of the Maryland institution participating in the vaccine trial. It's the University of Maryland School of Medicine.

Both errors have been corrected in the text.

So far in the government-directed sanofi pasteur trials, only 450 or so volunteers of a limited demographic have been evaluated at the three universities, Campbell said. Healthy men and women ages 18-64 were tested.

The next step in the trials would be to test children ages 2 to 9 and seniors over age 65. These further tests would only involve the two higher vaccine doses that were determined from Campbell’s current trial.

Maryland will continue to participate in these two trials; Campbell’s group is preparing for pediatric trials to begin in November.

Campbell also hopes to revise the first trial by giving the 154 Maryland volunteers a third booster shot, but that is pending the university’s approval.

$100 million of Vaccine Still in Trials

With countries worldwide fearing the potential devastation an avian flu outbreak could cause, Abrams said that the U.S. government has put in a $100 million order for sanofi pasteur’s vaccine.

“This is $100 million worth of bulk, concentrated antigen that is kept in storage,” Abrams said of the September 2004 contract the company signed with the U.S. Department of Health and Human Services.

Consider this like buying concentrated powdered iced tea mix. The government has the tea mix, but it’s waiting on the clinical trials to designate the optimal ratio of mix to water that will produce the most effective product.

The Department of Health and Human Services has also tapped Chiron and MedImmune to create avian flu vaccines, Campbell said. Four other institutions join the University of Maryland School of Medicine, the University of Rochester and the University of California in Los Angeles in a consortium that is evaluating and testing them.

The Chiron vaccine will begin its clinical trials soon; MedImmune is just starting to develop its product, Campbell said.

Copyright 2005 University of Maryland Philip Merrill College of Journalism


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