159. SARS-COV-2 vaccine responses in immunosuppressed patient populations

Background: Dialysis patients and immunosuppressed renal patients are at increased risk of COVID-19 and were excluded from vaccine trials. We conducted a prospective multicentre study to assess SARS-CoV-2 vaccine antibody responses in dialysis patients and renal transplant recipients, and patients receiving immunosuppression for autoimmune disease. Methods: Patients were recruited from four UK centres (ethics:20/EM/0180) and compared to healthy controls (ethics:17/EE/0025). SARS-CoV-2 IgG antibodies to spike protein were measured using a multiplex Luminex assay, after first, second and third doses of Pfizer BioNTech BNT162b2(Pfizer) or Oxford-AstraZeneca ChAdOx1nCoV-19(AZ) vaccine. Clinical data on COVID19 infection and immunosuppression was collected from patient interviews and electronic medical records. Results: 692 patients were included (260 dialysis, 209 transplant, 223 autoimmune disease (prior rituximab 128(57%)) and 144 healthy controls. 299(43%) patients received Pfizer vaccine and 379(55%) received AZ. Median age was 62 (range 19 – 95) years. At time of assessment of second vaccine response prior PCR confirmed SARS-CoV-2 infection was documented in 39 individuals (6%). In the autoimmune population, disease subgroups were classified as: ANCA-associated vasculitis (AAV) 133 (60%); systemic lupus erythematosus (SLE) 27 (12%); large vessel vasculitis 11 (5%) and other 52 (24%). 128 patients had received rituximab, a median of 162 (IQR 110 – 275) days prior to vaccination Following two vaccine doses, positive responses occurred in 96% dialysis, 52% transplant, 70% autoimmune patients and 100% of healthy controls. In dialysis patients, higher antibody responses were observed with Pfizer vaccination. Predictors of poor antibody response were triple immunosuppression (adjusted odds ratio [aOR]0.016;95%CI0.002-0.13;p<0.001) and mycophenolate mofetil (MMF) (aOR0.2;95%CI 0.1-0.42;p<0.001) in transplant patients; rituximab within 12 months in autoimmune patients (aOR0.29;95%CI 0.008–0.096;p<0.001) and patients receiving immunosuppression with chronic kidney disease stage 4 (eGFR 15-29ml/min, aOR0.031;95%CI 0.11–0.84;p=0.021) (see Figure). After second vaccine dose median s-antibody titres correlated strongly with time from most recent rituximab treatment (Spearman’s correlation coefficient 0.46; p<0.001), with increasing time from dose correlating with higher s-antibody titres. A lower median s-antibody was seen in those who had received Rituximab in the 6 months preceding a second vaccine dose (690 [IQR 175 – 12,767] compared to receiving a second vaccine dose greater than 6 months since most recent Rituximab treatment (27,975 (1,534 – 31,199); p