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A French patient claimed that a hepatitis B vaccine caused his multiple sclerosis, but scientists say there’s no evidence for such a link.

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Decision by Europe’s top court alarms vaccine experts

Did the European Union’s highest court just deal a blow to science? "Vaccines can be blamed for illness without scientific proof," read many headlines about the European Court of Justice’s (ECJ’s) ruling on the case of a French man who claimed that a hepatitis B vaccine caused his multiple sclerosis (MS). Alarmed experts pointed out that no link between the vaccine and MS has ever been established and fretted that the Luxembourg-based court had opened the floodgates to large numbers of spurious lawsuits.

But experts on liability law are divided on what the court's decision, announced in a jargon-filled press release on 21 June, will mean for medical product liability in Europe. Dorit Reiss of the University of California, Hastings College of Law in San Francisco says that rather than dealing a blow against science or vaccines, the court sought to balance individuals’ rights against society’s interest in preventing disease. But Jean-Sébastien Borghetti of the Panthéon-Assas University in Paris says the ruling leaves a worrying amount of room for judges in the European Union to ignore certain kinds of scientific evidence.

The case involves a French man, called “W” in court documents, who received the three recommended doses of a hepatitis B vaccine between December 1998 and July 1999. In August 1999, W developed symptoms of MS, an autoimmune attack on the protective sheath covering nerves. In 2006, he and his family sued Sanofi Pasteur, the vaccinemaker, claiming that the vaccine had caused the illness. (W died of MS-related complications in 2011.) Other people have made similar claims, but large epidemiological studies have found no connection between the vaccine and MS. 

W initially won his case. In 2009, the regional court in Nanterre ruled that, because he had no obvious previous health issues and no family history of MS, the appearance of symptoms shortly after the third vaccine dose was sufficient to conclude that the vaccine was the likely cause. In 2011 the Court of Appeal of Versailles overturned that decision, ruling that although W had made a convincing case that the vaccine caused his MS, he hadn’t shown that the vaccine was "defective," as required by liability law because for the population as a whole the vaccine's benefits outweighed its risks.

W and his family appealed to the Court of Cassation, France’s highest court, which evaluates whether lower courts have properly applied the law. It ruled that the appeals court decision on whether the vaccine was defective should have weighed the specific facts of W’s case, not the general risks and benefits of the vaccine, and handed the case to the Court of Appeal in Paris. (The French legal system assigns cases to a new court when a decision has been overturned.) The Paris court reached a different verdict: It found that W had not proved the vaccine had caused his MS. The court cited the lack of scientific evidence for a connection between the vaccine and MS, and the fact that the disease process is thought to begin years before symptoms appear—in other words, before W was vaccinated. 

If you start to have a significant number of court decisions in Europe that regard products as defective because of rare side effects, this could change things significantly.

Jean-Sébastien Borghetti, Panthéon-Assas University

W’s family appealed that ruling to the Court of Cassation as well, which then asked the European court for advice on whether courts can consider a plaintiff’s evidence, even if “medical research does not establish a relationship between the vaccine and the occurrence of a disease.” In other words, says Reiss, if scientific research is inconclusive, can an individual still plead their case with other types of plausible evidence, including circumstantial evidence? The court answered “yes.” At the same time, it said, the burden of proof is still on the plaintiff. Courts have to weigh the evidence in each individual case, and the plaintiff has to prove that they have the “preponderance of evidence,” Reiss notes.

The ruling doesn’t mean courts in the European Union are now free to ignore science, Reiss says. A vaccine manufacturer can counter a plaintiff’s circumstantial claims with, for example, epidemiological studies showing no plausible connection. But it puts the responsibility for funding large, expensive studies on a manufacturer, not on an individual who might have been harmed. “That makes a lot of sense,” Reiss says. “You don’t want to force plaintiffs to come up with medical research that doesn’t exist.”

Yet Borghetti sees a disturbing precedent in the ECJ ruling that any “abnormal and particularly serious damage” to a recipient could be reason to find a vaccine defective, even if its population-level benefits outweigh the risks. “If you start to have a significant number of court decisions in Europe that regard products as defective because of rare side effects, this could change things significantly.”

Just how far-reaching the verdict is will become clear in the years ahead. Paradoxically, it will likely have few consequences for the case that triggered it. The European court's conclusion seems to confirm the Court of Cassation’s rejection of the Versailles court’s ruling, but does not contradict the most recent decision, from Paris, which found that W failed to prove causation. Borghetti says that decision will most likely stand.