LAUSR

Dear Editor, Hemodialysis patients appear to be a population at high risk for coronavirus disease 2019 (COVID-19) due to the impaired immune responses. So far, development and duration of antibody response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in patients with end-stage kidney disease (ESKD) undergoing hemodialysis remains unclear. Whether it is similar to that of individuals in the general population or has a different course is still a mystery. Few reports discussed if serological tests are suitable for screening of SARS-CoV-2 infection in patients undergoing hemodialysis. To determine this, we conducted a retrospective study of five patients who were enrolled during the SARS-CoV-2 outbreak from January 25 to March 16, 2020 and followed up until December 16, 2020, in the First People's Hospital of Jingmen, Hubei Province, China. All five patients with ESKD had positive real-time reverse transcriptase-polymerase chain reaction (RT-PCR) results from a nasopharyngeal swab (Table 1). All patients had negative RT-PCR test results by Day 25 after the onset and the time from symptom onset to recovery ranged from 30 to 66 days. Complete blood count of these patients was performed at 1-day post-symptom onset (PSO) and revealed decreased lymphocyte cells counts. Total antibody was determined by chemiluminescence microparticle immunoassay kits (Xiamen Wantai, Xiamen, China). The total antibody (IgA, IgM, IgG) tests of two patients produced negative results (Table 1, patients 4 and 5). These two patients underwent repeated testing over 208 and 291 days, also using another antibody kit (Shenzhen YHLO Biotech Co., Ltd., Shenzhen, China), but the results remained negative. The three other patients had detectable antibody levels; of these, patients 2 and 3 were still seropositive at 360 and 340 days PSO, respectively. The data of patient 1 could not be tracked for the long term; his signal-tocutoff ratio of antibody was high at 541.43 at 65 days PSO. The antibody titers of patient 2 reached a plateau around 97 days (13–14 weeks) PSO and declined afterward. In the general population, the antibody titers peak earlier, mostly around 2–3 weeks after onset. Although some COVID-19–positive patients undergoing hemodialysis appear to produce antibodies, sometimes with a delay in the appearance of the antibody plateau, as shown in patient 2, others lose the capability to generate an antibody response. Our findings expand on those reported by Labriola et al. by indicating that some patients with ESKD undergoing