Vaccines in multiple sclerosis. The experience of BCG vaccination

Despite earlier reports showing an onset of multiple sclerosis (MS) or the occurrence of relapses after vaccination, more recent large epidemiological studies did not find this association and confirmed the safety of common compulsory vaccinations in MS. Moreover, experimental and epidemiological evidence suggests benefit of exposure to microbial products (in the absence of infection, as is the case of vaccination) in MS. Along this line, Bacillus Calmette-Guerin (BCG) vaccine was tried in early MS and resulted safe and effective in reducing disease activity on magnetic resonance imaging, as well as the risk of developing persistent T1-hypointense lesions ("black holes" - expression of tissue damage). Another trial in people with clinically isolated syndromes demonstrated a benefit of BCG with respect to the conversion to clinically definite MS over 5 years. These results suggest the use of BCG immediately after disease onset. Even the possible extension to people at risk of MS might be envisioned, given that the approach is safe, inexpensive and convenient.