The review pooled post-vaccination SARS-CoV-2 binding antibody levels in people with haematological malignancies, neurological disorders, rheumatic disease and other immune-mediated conditions on immunosuppressive therapy, alongside healthy controls. Levels were lowest with B-cell depletion, a 54.5-fold reduction (95% CI 34.5-86.2), and with S1P inhibitors, 24.8-fold (13.2-46.7). Linking predicted neutralising levels to earlier effectiveness estimates, protection tracked antibody level but sat lower in immunosuppressed people at any given level, in a preprint.
Why it is interesting: Antibody titre is the standard correlate of protection, and in this group it understates the risk that remains.