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

Clarke, C. L.; Prendecki, M.; Dhutia, A.; Edwards, C.; Prout, V.; Lightstone, L.; Parker, E.; Marchesin, F.; Griffith, M.; Charif, R.; Pickard, G.; Cox, A.; McClure, M.; Tedder, R.; Randell, P.; Greathead, L.; Guckian, M.; McAdoo, S. P.; Kelleher, P.; Willicombe, M.

Background Patients 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. Methods Three 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. Results One 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 serological evidence of SARS-CoV-2 antibodies at Time 0, were at significantly lower risk of being diagnosed with infection Conclusions ICHD 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.