LAUSR

On 22-Sep-2021 the U.S. Food and Drug Administration amended the emergency use authorization for the PfizerBioNTech COVID-19 Vaccine (tozinameran) to allow the use of a single booster dose, to be administered at least 6 months after completion of the primary series in certain populations including individuals 18 years of age and older at high risk of severe COVID-19 [1], while authorization for immunosuppressed patients was given 1 month earlier. However, boost vaccination of solid organ recipients commenced in Israel as early as mid-July. Additional at-risk populations, including elderly individuals, patients treated with maintenance dialysis and healthcare workers trailed briefly; the general adult population soon followed, resulting in increased protection from infection. Patients needing chronic renal replacement therapy are at risk for severe COVID-19 and have been shown to mount a lesser humoral response to mRNA vaccination [2]. In our single-center cohort we observed that reduced vaccine-elicited antibody levels in dialysis and kidney transplant patients were associated with increased infection rates [3]. Herein, we describe the short-term impact of booster administration in these patients, amidst a third wave of infections and deaths currently experienced in Israel primarily by the Delta variant, possibly amplified by waning immunity (Online Resource 1). Prior to initiation of vaccination we launched the COVID19 mRNA Vaccine Immunogenicity in patients with end stage Renal Disease (COVIReD) prospective cohort study designed to investigate the long-term kinetics and implications of antibody response to COVID-19 vaccine and infection in this vulnerable population. The study was approved by the local ethical Committee and its methods and preliminary results have been recently published [3]. In this update, we report patients’ humoral responses to booster vaccination. Antibodies were quantified using the LIAISON SARS-CoV-2 S1/S2 IgG test (DiaSorin, Sallugia, Italy). Risk factors for low antibody levels were assessed using a generalized linear mixed effects model accounting for repeated measurements (lme4/R statistical package). Infection risk was modeled with logistic regression. In total, we quantified anti-S1/S2 IgG levels at multiple time points in 183 maintenance dialysis patients, 280 kidney transplants and 74 controls not previously infected with COVID-19, of whom 82, 118 and 23, respectively, provided samples after receiving a vaccine booster. Figure 1a presents antibody median values across study groups and vaccination episodes. We had previously noted that with a most recent antibody level at or above 59 AU/ml no post-vaccination participant became infected, suggesting a COVID-19 protective cutoff [3]. Figures 1b and c show that prior to boosting (pre.v3), this level was achieved by 76% of controls, 35% of dialysis patients and 12% of transplant patients, while 8–117 days after booster injection respective rates were 100%, 91% and 56%. Risk factors for antibody levels < 59 AU/ml despite booster injection (control subjects excluded) were being in the transplant group, OR = 15.0 vs. dialysis * Iddo Z. Ben-Dov [email protected]