*Purpose: We aimed to investigate the prevalence and dynamics of SARS-CoV-2 IgG in kidney transplant recipients in the Bronx, New York, one of the epicenters of the pandemic

*Methods: Between March 16 and November 30, 2020, 158 patients tested positive by SARS-CoV-2 RT-PCR. From May 3 to November 30, 2020, 1042 patients were screened for SARS-CoV-2 IgG antibodies and 164 (15.7%) were tested positive (Figure).

*Results: Sixty of the 164 patients were previously diagnosed COVID-19 by RT-PCR, while the remaining 104 did not have significant symptoms and had not been previously tested by RT-PCR. Overall prevalence of COVID-19 diagnosis by RT-PCR and/or SARS-CoV-2 IgG in 1130 patients were 23.2%. Seventy RT-PCR positive patients were screened for SARS-CoV-2 IgG antibody at a median of 43 days post-diagnosis (IQR: 29-57) and 60 (85.7%) were positive. A total of 39 patients out 164 who previously tested positive for SARS-CoV-2 IgG (25 diagnosed with IgG and 14 with RT-PCR) were retested at a median time of 105 days (IQR: 83-116). Twenty patients (51.3%) became seronegative at a median time of 107 days (IQR: 87-134) from their first positive SARS-CoV-2 IgG. Six patients out of 14 (43%) who were diagnosed by positive RT-PCR became seronegative at a median time of 105 days (IQR: 83-166) from their first positive SARS-CoV-2 IgG while 14 patients out of 25 (56%) who were initially diagnosed by a positive SARS-CoV-2 IgG, became seronegative at a median time of 112 days (IQR: 91-138) from date of diagnosis

*Conclusions: . In summary, 40% of kidney transplant recipients were asymptomatic or mildly symptomatic and developed SARS-CoV-2 IgG without requiring testing by SARS-CoV-2 RT-PCR. However, half of the patients who initially developed antibodies lost them over time raising the questions of lasting immunity against SARS-CoV-2 and how effective are those antibodies.

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