Sunday, November 6, 2011

Panel Endorses Anthrax Vaccine Study in Children

It’s an ethically fraught question almost without precedent in modern medical research: Should children be enrolled in a clinical trial of the anthrax vaccine, which is almost certain not to help them and may harm them? Or should the U.S. government gamble and wait for a possible attack before exposing children to the vaccine for the very first time? Last week, the full National Biodefense Science Board (NBSB) voted 12–1 in favor of a trial assuming its ethics are approved by a review board, saying that it was too uneasy to risk a mass science experiment on thousands of children after a bioterror strike, even if some consider that possibility remote.
“Before vaccines are given to children, they are tested in children,” says Daniel Fagbuyi, the medical director of disaster preparedness and emergency management at Children’s National Medical Center in Washington, D.C. “We do not want to set a new precedent.” Fagbuyi chaired an NBSB working group that in September recommended a clinical trial.
Last week’s vote isn’t binding, and even if a study goes forward, the U.S. Department of Health and Human Services (HHS) will need to jump through many hoops to get it up and running. Although clinical trials are all about gathering information that benefits others, rules for studies on children are more stringent than for those on adults. It’s legally and ethically challenging to offer a child an experimental treatment that’s even slightly risky if the chance of benefiting is all but nonexistent, as is the case with the anthrax vaccine.
The vaccine has been around for decades, and more than 2 million adults, mostly military personnel, have received it. But HHS and others who fret about a bioterror attack worry that this isn’t enough. A quarter of the U.S. population is under 18, and no one has examined how children and teenagers react to the vaccine—for instance, whether they need different doses to ensure safety and effectiveness.
There is considerable variation in the way vaccines are administered to people of different ages. With the tetanus vaccine, “the same dose is given to a 2-month-old infant as an NFL football player,” says John Grabenstein, senior medical director for adult vaccines at Merck and a member of the NBSB. For the hepatitis B vaccine, the dose is lower in children; for flu, it may also be lower and is sometimes given as two small doses, rather than one larger one. “There’s enough idiosyncrasies that you can’t assume” how children will react to a vaccine based on what you know in adults, says Grabenstein, who voted in favor of a clinical trial. “The only way to know is to try.”
In the bioterror world, a similar question has come up at least once before. Soon after the 11 September attacks and the anthrax mailings, officials were concerned about weaponized smallpox. There wasn’t enough of the existing smallpox vaccine, Dryvax, to go around, so the government considered whether to test it in 2- to 5-year-olds to see whether they could gain the same benefi t from a smaller dose, thus stretching supplies. In some ways the proposed trial was more problematic than an anthrax study, says Douglas Diekema, a pediatrician and bioethicist at Seattle Children’s Research Institute: Smallpox vaccine is considered riskier than anthrax vaccine, and many felt the chance of a smallpox attack was much more remote than one using anthrax. For various reasons, the smallpox study never went forward. Fagbuyi finds the comparison lacking. Anthrax vaccine, he says, is “totally different than Dryvax” and has been tested in very large groups of people. The U.S. Centers for Disease Control and Prevention (CDC) is wrapping up a study it began 11 years ago in healthy adults, analyzing vaccine safety and whether people can produce suffi cient protective antibodies with fewer doses of the vaccine, and by receiving it in muscle rather than under the skin, which results in fewerside effects. “This is a very safe vaccine,” and side effects, like redness and swelling or brief fever, are similar to what’s seen in many childhood vaccines, says Nancy Messonnier, chief of CDC’s bacterial vaccine branch. Like vaccines that protect against diphtheria and tetanus, for example, the anthrax vaccine is made with a protein from anthrax bacteria that’s harmless on its own.
None of this appeases pediatricians and bioethicists who consider an anthrax vaccine trial in children wrongheaded. “These children are going to be exposed to a vaccine from which they have no chance of benefiting. The only possible outcome is that nothing will happen, … or they’ll have a safety issue,” says Paul Offit, an infectious disease specialist at the Children’s Hospital of Philadelphia in Pennsylvania, who often speaks out in favor of childhood vaccination. Diekema agrees. Scientifically, a trial like this makes sense, because it’s the best way to gather the necessary information. That said, “it’s a difficult study to justify.”
Then there’s the question of who would volunteer their children. Fagbuyi, who served in Iraq and received the anthrax vaccine himself, says that some military members, first responders, and scientists working
with anthrax—many of whom get the vaccine now—have expressed interest in having their children vaccinated, too. They may be comfortable enrolling them in an anthrax study, if it gets off the ground.



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