Humoral immunity trends in a hemodialysis cohort following SARS‐CoV‐2 mRNA booster: A cohort study

Abstract

Background and AimsPatients with end stage kidney disease on hemodialysis are vulnerable to SARS‐CoV‐2 infection. Current guidelines recommend boosters of SARS‐CoV‐2 mRNA‐based vaccines. The long‐term humoral response of hemodialysis patients infected with SARS‐CoV‐2 after receiving a booster of SARS‐CoV‐2 mRNA‐based vaccines has been incompletely characterized. Here, we determined the long‐term humoral response of hemodialysis patients to two and three doses of the Pfizer BioNTech (BNT162b2) mRNA SARS‐CoV‐2 vaccine and investigated the effect of postbooster SARS‐CoV‐2 infection on antibody levels over time.MethodsSamples were collected on a monthly basis and tested for anti‐SARS‐CoV‐2 antibodies against anti‐spike S1 domain. Thirty‐five hemodialysis patients were enrolled in the original study and 27 of these received a booster. Patients were followed up to 6 months after the first two doses and an additional 7 months after the third BNT162b2 dose. Results are presented as the internationally harmonized binding antibody units (BAU/mL).ResultsAntibody level significantly increased from prebooster to 2 weeks postbooster, with a median [25th, 75th percentile] rise from 52.72 [28.55, 184.7] to 6216 [3806, 11,730] BAU/mL in the total population. Of patients with a negative or borderline detectable antibody level 6 months after vaccination who received a third dose, 89% developed positive antibody levels 2 weeks postbooster. Postbooster antibody levels declined an average rate of 29% per month in infection‐naïve patients. Antibody levels spiked in patients infected with SARS‐CoV‐2 after receiving a booster but declined rapidly. No patients infected postbooster required hospitalization.ConclusionsA third dose of BNT162b2 restores antibody levels to high levels in dialysis patients but levels decline over time. A third dose did not necessarily prevent infection, but no patients suffered severe infection or required hospitalization. SARS‐CoV‐2 recovered patients appear to have a blunted rise in antibody levels after a third dose. Although patients infected with SARS‐CoV‐2 postbooster had an immediate spike in antibody levels, these declined over time.