How can we tell whether a patient already on rituximab will have an immunogenic response to Pfizer COVID-19 vaccination? Better chance of response if: - RA or SLE, not AAV or IIM - high serum IgG pre-last RTX - longer time since last RTX Israeli data #ACR21 ABST0437 @RheumNow https://t.co/yyuFd0eDH6