Is SARS-CoV-2 Serology Relevant for Hemodialysis Patients With COVID-19?

To the Editor:

Although dialysis patients are known to have impaired antibody responses to pathogens and fluctuation of antibody levels, the response to coronavirus disease 2019 (COVID-19) in this population remains to be determined. De Vriese and Reynders present the first evaluation of potential antibody responses in a dialysis population. We agree that 2 sequential negative COVID-19 swabs before de-isolating dialysis patients is a reasonable approach, as we recently demonstrated. De Vriese and Reynders studied the presence of immunoglobulin G (IgG) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) protein in 7 patients and concluded that patients develop an antibody response within 15 days. Although we acknowledge that these findings are novel, we highlight that they might not be applicable to other dialysis populations with COVID-19 infection. First, the infection rate in their population was very low (7/289 [2.5%]) and most of these patients had a severe form of the disease (3 [43%] died and 1 was still in the intensive care unit [ICU]). In comparison, in our experience, 11.3% of our hemodialysis population had COVID-19 infection and only 7 of 76 (9.2%) died. IgG against SARS-CoV-2 N protein has been shown to be higher in ICU compared with non-ICU patients. Therefore, it remains to be elucidated whether those results are applicable to any hemodialysis population and whether there is a prognostic role in assessing anti-spike (S) protein IgG in combination with IgG against SARS-CoV-2 N protein. Moreover, it remains to be confirmed how long these antibodies will last and their clinical relevance in larger populations.