Longevity of SARS-CoV-2 immune responses in haemodialysis patients and protection against reinfection

ABSTRACT

BackgroundPatients with end stage kidney disease (ESKD) receiving in-centre haemodialysis (ICHD) have had high rates of SARS-CoV-2 infection. Following infection, ICHD patients frequently develop serological evidence of infection, even with asymptomatic disease. The aim of this study is to investigate the durability and functionality of immune responses to SARS-CoV-2 infection in ICHD patients. MethodsThree hundred and fifty-six ICHD patients were longitudinally screened for SARS-CoV-2 antibodies and underwent routine PCR-testing for symptomatic and asymptomatic infection. Patients were screened for nucleocapsid protein (anti-NP) and receptor binding domain (anti-RBD) antibodies. Patients who became seronegative at 6 months were investigated for SARS-CoV-2 specific T-cell responses. ResultsOne hundred and twenty-nine (36.2%) patients had detectable antibody to anti-NP at Time 0, of which 127 (98.4%) also had detectable anti-RBD. At 6 months, of 111 patients tested, 71(64.0%) and 97 (87.4%) remained anti-NP and anti-RBD seropositive respectively, p<0.001. For patients who retained antibody, both anti-NP and anti-RBD levels reduced significantly after 6 months. Ten patients who were anti-NP and anti-RBD seropositive at Time 0, had no detectable antibody at 6 months; of which 8 were found to have SARS-CoV-2 antigen specific T cell responses. Independent of antibody status at 6 months, patients with baseline positive SARS-CoV-2 serology were significantly less likely to have PCR confirmed infection over the following 6 months. ConclusionsICHD patients mount durable immune responses 6 months post SARS-CoV-2 infection, with <3% of patients showing no evidence of humoral or cellular immunity. These immune responses are associated with a reduced risk of subsequent reinfection. SIGNIFICANCE STATEMENTFollowing infection with SARS-CoV-2, patients with end stage kidney disease (ESKD) frequently develop serological evidence of infection, even with asymptomatic disease. Patients with ESKD receiving in-centre haemodialysis (ICHD) have had high rates of SARS-CoV-2 infection. What is not known is how durable the serological responses in ESKD patients are or whether evidence of prior immune responses protect patients from reinfection. In this study of 356 ICHD patients, at 6 months following the detection of SARS-CoV-2 antibodies, fewer than 3% of patients lacked evidence of either humoral or cellular immunity. Furthermore, patients with serological evidence of infection had a significantly lower risk of being diagnosed with subsequent infection or reinfection, suggesting functional immune protection.