US soldiers are suing the Department of Defense over forced vaccinations. Credit: Reuters/Randy Davey ME Health Vaccination Camp Lejeune

US soldiers are battling with the federal government over the military's anthrax vaccination scheme. After a flurry of rulings and counter-rulings over whether the vaccine can protect soldiers from inhalation anthrax, a federal court in January lifted a temporary ban on the program. But the debate over the drug's efficacy is likely to continue as the case moves through the courts.

The US has vaccinated more than a million soldiers since 1998. Opponents of the program say the vaccine causes both long- and short-term health problems, including pneumonia, joint pain and gastrointestinal disorders.

Thousands of adverse event reports have been filed with the US Food and Drug Administration (FDA). However, based on existing evidence, several scientific panels have determined that the vaccine is safe. Those who refuse the shot have been disciplined and, in some cases, court-martialed.

No one argues that the vaccine is effective against cutaneous anthrax. A 1962 study—the only placebo-controlled human trial of the anthrax vaccine—followed 1,200 workers in four textile mills. Only 1 of the 26 subsequent cases of anthrax occurred in a fully vaccinated worker, but only 5 of the 26 cases were of inhalation anthrax (Am. J. Public Health 52, 632–645; 1962). Based on those data, a scientific panel in 1973 concluded that inhalation anthrax “occurred too infrequently” to assess the vaccine's efficacy against it.

The panel's recommendations languished in regulatory limbo, however. They were finally published in 1985, but the FDA never formally adopted or rejected them. In his initial ruling, Judge Emmett Sullivan said the vaccine is an investigational drug being used for an unapproved purpose. He ruled that the US “cannot demand that members of the armed forces also serve as guinea pigs for experimental drugs.”

One week later, the FDA published a belated analysis of the 1985 recommendations, disputing the panel's finding. Analyzing the two exposure routes together, it concluded the vaccine is 92.5% effective against all forms of anthrax.

Based on the FDA's new analysis, the judge lifted the temporary ban. But the new interpretation of the data is a matter of semantics, not science, argues Gene Stollerman, who chaired the 1973 panel. “I will defend our interpretation,” Stollerman says. “Any other interpretation has to do with legal issues.”

The existing evidence doesn't meet the FDA's usual standards, adds Mark Zaid, the Washington-based lawyer who brought the case against the US Department of Defense (DOD). “When had the FDA ever said to anyone, 'it's probably effective so we're going to give you a license'?” Zaid asks.

Confident it will prevail, the DOD has ordered a $30 million batch of the vaccine. Laywers for the soldiers, meanwhile, have asked the judge to grant the case class-action status.

This material is part of Nature Medicine's 10 year anniversary series. For more content related to these special focus issues, please see http://www.nature.com/nm/special_focus/anniversary/index.html