High Prevalence of Asymptomatic COVID-19 Infection in Hemodialysis Patients Detected Using Serologic Screening.

Background Strategies to minimize the risk of transmission and acquisition of COVID-19 infection in patients with ESKD receiving in-center hemodialysis have been rapidly implemented across the globe. Despite these interventions, confirmed COVID-19 infection rates have been high in the United Kingdom. Prevalence of asymptomatic disease in an adult hemodialysis population has not been reported. Also, to our knowledge, the development of humoral response to SARS-CoV-2 has not been previously reported in this population. Although serologic testing does not provide information on the infectivity of patients, seroprevalence studies may enable investigation of exposure within dialysis units and hence, assessment of current screening strategies. Methods To investigate the seroprevalence of SARS-CoV-2 antibodies in a hemodialysis population, we used the Abbott IgG assay with the Architect system to test serum samples from 356 patients receiving in-center hemodialysis for SARS-CoV-2 antibodies. Results Of 356 patients, 121 had been symptomatic when screened before a dialysis session and received an RT-PCR test; 79 (22.2% of the total study population) tested positive for COVID-19. Serologic testing of all 356 patients found 129 (36.2%) who tested positive for SARS-CoV-2 antibodies. Only two patients with PCR-confirmed infection did not seroconvert. Of the 129 patients with SARS-CoV-2 antibodies, 52 (40.3%) had asymptomatic disease or undetected disease by PCR testing alone. Conclusions We found a high seroprevalence of SARS-CoV-2 antibodies in patients receiving in-center hemodialysis. Serologic evidence of previous infection in asymptomatic or PCR-negative patients suggests that current diagnostic screening strategies may be limited in their ability to detect acute infection. Significance Statement Strategies to limit acquisition and transmission of SARS-CoV-2 infection in patients with ESKD receiving in-center hemodialysis have been implemented globally. Despite these measures, acute SARS-CoV-2 infection rates confirmed by RT-PCR testing have been high in the United Kingdom. The seroprevalence rate in an in-center hemodialysis adult population has not been reported previously. In a study of 356 patients receiving in-center hemodialysis, the authors report a 36.3% seroprevalence rate. They also found that 40.3% of patients with IgG SARS-CoV-2 antibodies had either asymptomatic infection or undetected disease by PCR testing alone. These findings reveal limitations of current diagnostic screening strategies for active SARS-CoV-2 infection using PCR testing of individuals screened for symptoms prior to dialysis sessions. Effective screening is likely to require a hybrid strategy of PCR and serologic testing.