*Purpose: The full spectrum of COVID-19 disease and the impact of disease severity on antibody response and viral shedding dynamics in transplant patients is unclear. The aims of this study were to determine the outcomes COVID-19 in SOT recipients, and correlate disease severity with antibody response and viral dynamics following SARS-CoV-2 infection.

*Methods: We performed a single-centre, prospective, observational study of adult SOT patients infected with COVID-19 and followed patients for 4 weeks. Severe disease was defined as either hospitalization attributable to COVID-19 or death. SARS-CoV-2 serology using available sera was assessed by a commercial anti-nucleoprotein (NP) assay (Abbott). Viral loads on serial nasopharyngeal swabs were assessed using real time RT-qPCR (Norgen Biotek).

*Results: Between March and November 2020, 55 SOT recipients had PCR-confirmed SARS-CoV-2 infection. 78.2% were male with a median age 55 years (IQR 43-65), median time post-transplantation of 6 years (IQR 1.6-11.5). Transplant types were kidney (53.7%), liver (20.4%), lung (13.0%), kidney-pancreas (9.3%) and heart (3.7%). The majority of patients (65.5%) had >=2 comorbidities other than transplantation. Hospitalization occurred in 55.6% and 33.6% required supplemental oxygen. Other outcomes were ICU admission (16.7%), mechanical ventilation (13.0%), ECMO (1.9%), and all-cause mortality (5.6%). All deaths were lung transplant recipients. On univariate analysis, factors significantly associated with severe disease were >=2 comorbidities (p=0.034), and African-American race (p=0.015). Immunosuppression was reduced in 66.7% of cases, most commonly the antiproliferative agent. A subgroup of patients (n=26) underwent SARS-CoV-2 antibody testing and 23/26 (88%) had antibodies by day 14 post-symptom onset. The three negative patients had mild disease. A subgroup of patients (n=23) had serial nasopharyngeal swabs for viral load. The median duration of positivity was 15 days (IQR 10-24) (Fig 1,2). The median peak VL measured was 4,669 copies/mL (IQR 274 to 103,038 copies/mL). Peak viral load and duration of shedding were not significantly different between hospitalized and non-hospitalized groups (p=0.59 and p=0.52 respectively).

*Conclusions: SOT patients experience a spectrum of COVID-19 although mortality was low in our cohort likely due to greater capture of mild cases in the outpatient population. Virus is shed for long durations despite most transplant recipients generating SARS-CoV-2 directed antibody responses.

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