The French government in 1998 decided to temporarily suspend hepatitis B vaccine programs in schools after several cases of multiple sclerosis were reported a few weeks after the vaccine had been administered in 1995 and 1997 as part of a mass immunization program. Multiple sclerosis is a chronic degenerative disease of the central nervous system. A research team led by Alberto Ascherio, associate professor of epidemiology and nutrition at the Harvard School of Public Health, found no association between the hepatitis B vaccine and the development of multiple sclerosis. The authors conclude that alterations in hepatitis B vaccination policies are not warranted and that changes could compromise or delay control of the disease. “The study’s results appear to contradict previous concerns raised in other research and justifies keeping hepatitis B vaccination programs and policies firmly in place,” Ascherio said.