MO884: Humoral Response of Hemodialysis Patients Following Comirnaty Vaccine Booster is Equivalent to Healthy Subjects
Authors: Angel-Korman Avital , Brosh-Nissimov Tal , Leiba Adi 
Published: May 2022

Abstract

BACKGROUND AND AIMS
Comirnaty, the mRNA-based vaccine against COVID-19 has shown initial great success in preventing infection and severe disease with SARS-CoV-2 in the general population [1]. Humoral response following the second dose of Comirnaty in maintenance hemodialysis (MHD) patients has been shown to be diminished [2–4]. Waning of antibody levels in MHD patients was also demonstrated to be much more profound after several months compared with healthy controls [5].
From August to September 2021, a booster vaccine dose was distributed to the population in Israel, 5 and 6 months after the second vaccine dose. Our aim was to evaluate the humoral response following the second and third vaccine doses in MHD patients.

METHOD
Anti-spike protein (anti-S) seropositivity rates and antibody levels of 409 MHD patients from 13 hemodialysis units in Israel were obtained at 3 time points–2 and 3 months and around 6 months following the second dose and were compared with 148 control group volunteers. A third sample was obtained in a subset of the original cohort—75 MHD patients and 31 controls, ∼2 months after the booster dose.

RESULTS
Included in our analysis were 75 MHD patients of which 62 (83%) received a third booster vaccine dose and 31 controls of whom 26 (84%) received the booster dose. Mean age was 68.8 ± 12.7 years in the MHD group and 50.7 ± 10.2 years in the control group (P &lt; 0.0001). Initial antibody response, which was examined in 409 MHD patients was diminished compared with 148 controls: seropositivity rates of 89% versus 99.3% and anti-S levels of 69.6 AU/mL (IQR 33–120) versus 196.5 AU/mL (IQR 119–246), respectively. Anti-S seropositivity rates and antibody levels significantly declined about 6 months after the second dose, in both MHD patients and in control group participants, however they decreased much more dramatically in MHD patients: seropositivity of 74% versus 98% and antibody titer decline from 63.8 AU/mL (IQR 33.3–113) to 31 (14–59.5) (P &lt; 0.0001), versus 201 (125–242) to 143 (89–199) (P &lt; 0.0001) in MHD patients and controls, respectively.
Nevertheless, in MHD patients who received all three vaccine doses, anti-S seropositivity rate was not significantly different from control group participants at a median of 56 (IQR 38–86) days post booster. Anti-S levels in MHD patients significantly increased after the third booster vaccine, in a similar fashion to control group participants, reaching 1530 AU/mL (IQR 801–2810) and 1945 AU/mL (IQR 996–3390) (P = 0.182), respectively (Figure 1). Contrary, anti-S levels in COVID-naïve MHD patients who did not receive the third booster vaccine did not significantly change between the second and third sampling time points (Figure 2).

CONCLUSION
MHD patients are able to mount their humoral response to a similar level as healthy controls following a third booster dose of Comirnaty despite an initial diminished response and exaggerated antibody waning. Longer follow up is needed in order to establish whether this seemingly equivalent response also translates into better protection and decreased morbidity and mortality among MHD patients.