Anti-CD20 – Vaccine Response Attenuation — SCE Neurology MCQ

Correct answer: D — Anti-CD20 therapies (ocrelizumab, rituximab) significantly attenuate humoral (antibody) responses to vaccines — vaccination should be completed before starting anti-CD20 therapy where possible, and timing of vaccination relative to infusion cycles can optimise response

Anti-CD20 therapies deplete B cells, significantly reducing the humoral (antibody) response to vaccines. This was highlighted during the COVID-19 pandemic when MS patients on ocrelizumab had markedly lower antibody responses to SARS-CoV-2 vaccines compared with patients on other DMTs. Mitigation strategies: (1) complete all recommended vaccinations (including COVID-19, influenza, pneumococcal) BEFORE starting anti-CD20 therapy (≥6 weeks before), (2) time vaccination at least 12 weeks after the last infusion and ≥4 weeks before the next to maximise B-cell recovery, (3) T-cell responses may still provide some protection despite low antibodies, (4) household contacts should be vaccinated. A: Significant attenuation occurs. C: Responses are reduced. D: All vaccines are affected (though live vaccines are also contraindicated). E: T-cell responses may be preserved but humoral is impaired.

Reference: ABN MS Guidelines (2022); Achiron et al. COVID-19 Vaccination in MS