How Long Do SARS-CoV-2 Antibodies Last in Dialysis Patients?

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Nearly all dialysis patients infected with SARS-CoV-2 show sustained immune responses through 6 months' follow-up, according to a pre-proof paper in Kidney International.

The researchers screened for two types of SARS-CoV-2 antibodies in a cohort of 356 patients receiving hemodialysis at two UK dialysis centers. Specifically, samples were tested for antibodies to the nucleocapsid protein (anti-NP) and the receptor binding domain (anti-RBD) of the spike protein. Durability and functionality of immune responses to SARSCoV-2 were assessed over time.

At initial screening, 38% of dialysis patients tested positive for one or both types of SARS-CoV-2 antibodies. Most patients (127 of 136) were positive for both anti-NP and anti-RBD. Two patients were positive for anti-NP but negative for anti-RBD, whereas 7 patients showed the opposite pattern.

At 6 months' follow-up in 301 patients, 64% were still positive for anti-NP and 85% for anti-RBD. Cellular immune responses were tested in 10 patients whose antibody responses had waned: 8 had detectable T cell responses.

Of the original 192 patients who were positive for anti-NP, 97% had persistent serologic or cellular immune responses at 6 months—even those with mild or asymptomatic SARS-CoV-2 infection. On assessment of clinical outcomes, patients who initially tested positive for SARS-CoV-2 antibodies were less likely to have polymerase chain reaction-positive infection, regardless of their 6-month antibody status.

Dialysis patients have high rates of SARS-CoV-2 infection with a high risk of poor outcomes. In this cohort study, close to 40% of in-center hemodialysis patients tested positive for SARS-CoV-2 antibodies.

Most patients remain antibody positive for 6 months, and nearly all have evidence of humoral or cellular immunity associated with reduced risk of subsequent SARS-CoV-2 infection. “Together, these data suggest that immune responses post-infection may be protective against reinfection,” the investigators conclude [Clarke CL, et al. Longevity of SARS-CoV-2 immune responses in hemodialysis patients and protection against reinfection. Kidney Int, published online ahead of print March 24, 2021. doi: 10.1016/j.kint.2021.03.009;].