Predictors of severe COVID-19 in kidney transplant recipients in the first and second waves: Analysis of the spanish registry

Purpose: Through banked serum samples from transplant candidates across Georgia, we characterize the prevalence, timing, and duration of SARS-CoV-2 seropositivity and investigate the impact on HLA alloantibodies. Methods: We used a Luminex-based assay to detect antibodies against SARSCoV- 2. The assay is a semiquantitative measure of antibodies against Full Spike, S1, S2, Nucleocapsid and RBD epitopes as well as antibodies against 4 common coronaviruses, SARS-1, and MERS. We selected 400 waitlist candidates from Georgia counties with an above average case rate (>2200 cases per 100,000 people) as of August 2020 and screened the most recent serum sample from each candidate. For positive tests, we ran sequential historical samples to determine the earliest positive date and subsequently performed a geographic analysis of positive cases. Additionally, we cross-referenced SARS-CoV-2 reactivity with HLA antibody levels. Results: Of 400 waitlist candidates, 33 tested positive for antibodies to SARSCoV- 2. Five of those candidates were positive on samples taken from as far back as 2019, pre-Covid. These samples also demonstrated high levels of binding to common coronavirus spike proteins. After removing these false positives (1.3%), there was a 7% test positivity rate. In counties with positive candidates, rates were approximately 10x higher than published by the GA department of public health. All 28 seropositive candidates maintained positive serology for the duration of the testing period (maximum of 5 months). Positive and negative groups had similar distributions of peritoneal and hemodialysis patients. In the 15 seropositive candidates with panel reactive antibodies (PRA), there was no apparent change associated with seroconversion. Conclusions: Our analysis of transplant waitlist candidate SARS-CoV-2 serologies demonstrated a higher rate of positivity than that published by the state for the general population. This may be attributed to asymptomatic infections, insufficient testing, or an increased risk in this immune dysregulated population. While we intend to continue monitoring positive candidates to determine the duration of antibody presence, it is encouraging that candidates remained positive for the time studied. Finally, seroconversion does not appear to be a risk factor for the development of donor specific antibodies in this cohort of patients.