TB Vaccine May Work Against Multiple Sclerosis
More brain lesions seen in people who got dummy injection
After five years, 70 percent of those who received the placebo had developed MS, compared to 42 percent of those given the vaccine, the researchers said. No major side effects were reported during the study.
Ristori said it's not clear how the vaccine is protecting against multiple sclerosis. "There seems to be complex, multiple effects on brain inflammation," he said.
Because lesions were reduced in people who received the vaccine, Ristori said, it might also be helpful for people who already have MS.
The authors of an accompanying journal editorial said this study's findings lend support to the "hygiene hypothesis." This theory suggests that a lack of infections during childhood may affect the development of the immune system, and that vaccinating with a live vaccine may help induce a "protective immunity" against MS.
Nicholas LaRocca, vice president of health care delivery and policy research for the National Multiple Sclerosis Society, said this is the latest in a number of studies that have looked at what environmental factors contribute to the development of MS.
"What we're learning is that the immune system isn't a self-contained entity, but that it has a lot of interactions with other things in the body," LaRocca said.
"This study adds to what we know about MS," he said. "But it's just one piece of a big puzzle."
For now, the editorial authors recommend against using the vaccine to treat clinically isolated syndrome or full-blown MS because the long-term safety and effectiveness of the treatment is unknown.
The tuberculosis vaccine often is given to infants and small children in countries where the disease is common. U.S. health officials recommend it only when tuberculosis is likely.