A substantial proportion of patients receiving in-center hemodialysis (HD) have antibodies to SARS-CoV-2, the novel coronavirus that causes COVID-19, but do not display symptoms of infection or test negative on the reverse transcription-polymerase chain reaction (RT-PCR) molecular diagnostic test, a new study finds.

A total of 356 patients received maintenance HD at 2 clinics in London, United Kingdom, from April 27 to May 7, 2020. Of these, 121 patients were symptomatic at entry and received an RT-PCR test of nasopharyngeal swab specimens, including 79 who tested positive for COVID-19 nucleic acids. Those who tested positive had higher peak C-reactive protein and ferritin levels and lower nadir lymphocyte counts than those who tested negative, in agreement with previous research.

Separate serologic testing of all 356 patients found that 129 (36%) tested positive for IgG SARS-CoV-2 antibodies. Two patients with PCR-confirmed infection (both with a history of immunosuppression) did not display antibodies on serologic testing. Notably, 40.3% of patients with SARS-CoV-2 antibodies had asymptomatic or undetected disease at RT-PCR testing.

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“None of these patients would have been isolated, which means that they may have been a source of infection transmission for a period within the dialysis centers,” Maria Prendecki, MBBS, of Imperial College London in London, United Kingdom, and colleagues stated in the Journal of the American Society of Nephrology. “Although the use of personal protective equipment would have limited this risk, these results highlight the limited utility of current diagnostic screening strategies within dialysis cohorts.”

It is likely that effective screening strategies within HD populations need to consist of both PCR and antibody screening, the investigators concluded. They acknowledged that seropositivity does not equate with infectivity, but it is a marker of COVID-19 exposure.

Disclosure: One author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Clarke C, Prendecki M, Dhutia A, et al. High prevalence of asymptomatic COVID-19 infection in hemodialysis patients detected using serologic screening [published online July 30, 2020]. J Am Soc Nephrol. doi: 10.1681/ASN.2020060827