BCG vaccine may reprogram brain immunity and amyloid handling in aging

A small year-long open-label study suggests the Bacillus Calmette-Guérin (BCG) vaccine can boost immune cell responsiveness in blood and cerebrospinal fluid without triggering sustained brain inflammation. In older adults without Alzheimer’s pathology, beta-amyloid shifted from CSF to the blood, hinting at improved clearance from the brain, while those with existing biomarkers did not show the same changes. The findings offer a potential mechanism linking BCG to lower Alzheimer’s risk but are preliminary, as the study lacked a placebo group and involved only 23 participants, requiring larger randomized trials to confirm any clinical benefit.