Bacille Calmette-Guérin (BCG), a live vaccine used to prevent tuberculosis, may prevent multiple sclerosis (MS) if it is given to patients early—at the disease's first sign, a neurological episode called clinically isolated syndrome. This episode may involve numbness, vision problems, or problems with balance.
In a double-blind study that included 73 people who evidenced clinically isolated syndrome, 33 were vaccinated with BCG, and 40 received a placebo. All of the participants had brain scans once a month for six months. They then received the MS drug interferon β-1a for a year. After that, they took the MS drug recommended by their neurologist. The development of definite MS was evaluated for five years after the start of the study.
The results of this study were described in a paper published December 4 in Neurology entitled, “Effects of Bacille Calmette-Guérin after the first demyelinating event in the CNS.” The authors of this paper, scientists based at Sapienza University of Rome, Italy, wrote, “During the initial six months, the number of cumulative lesions was significantly lower in vaccinated people.” In addition, “the number of total T1-hypointense lesions was lower in the BCG group at months 6, 12, and 18.”
By the end of the study, 58% of the vaccinated people had not developed MS, compared to 30% of those who received the placebo. No major side effects were detected during the study, and there were no differences in side effects between those who received the vaccine and those who didn’t.
The study’s first author, Giovanni Ristori, M.D., Ph.D., expressed cautious optimism about the implications of the study, which included a fairly small number of patients. “These results are promising, but much more research needs to be done to learn more about the safety and long-term effects of this live vaccine,” said Dr. Ristori. “Doctors should not start using this vaccine to treat MS or clinically isolated syndrome.”
In an editorial that accompanied the study, Dennis Bourdette, M.D., Roy and Eulalia Swank Family Research Professor and chairman of the department of neurology at the Oregon Health and Science University School of Medicine, noted that the BCG vaccine’s effects provide support for the “hygiene hypothesis.” According to this hypothesis, better sanitation and use of disinfectants and antibiotics may account for some of the increased rate of MS and other immune system diseases in North America and much of Europe compared with Africa, South America, and parts of Asia.
“The theory,” wrote Dr. Bourdette, “is that exposure to certain infections early in life might reduce the risk of these diseases by inducing the body to develop a protective immunity.”