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

Patients 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.

Samples 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).

Antibody 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.

A 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.