MO839: Anti-SARS-COV-2 Antibodies in Patients on Maintenance Haemodialysis
Authors: Morisi Niccolò , Scarmignan Roberta , Alfano Gaetano , Donati Gabriele 
Published: May 2022

Abstract

BACKGROUND AND AIMS
Traditional vaccination strategies had poor effectiveness in host response in haemodialysis (HD) patients [1]. That is why a booster dose of SARS-CoV-2 vaccine is highly recommended to prevent worse outcomes. The aim of the study was to determine the humoral response in HD patients after the booster dose of mRNA-1273 vaccine (Moderna) [2].

METHOD
In October 2021, HD patients received the booster dose and in November 2021 Anti-SARS-CoV-2 antibodies (Ab) were assessed during a cross-sectional retrospective study. Clinical data, laboratory tests and immunomodulatory therapies (IT) were collected from medical records. Of 194 patients enrolled, 26 were excluded for IT. SARS-CoV-2 Ab dosage was carried out in 168 patients using DiaSorin LIAISON SARS-CoV-2 trimetricSpike IgG (DiaSorin, Saluggia, Italy). Absence of humoral immunity was diagnosed when the antibodies value was &lt; 33.8 BAU/mL. For statistical analysis we used Shapiro–Wilk, Mann–Whitney, Spearman's correlation and Kruskal–Wallis test. A P-value &lt; 0.05 was considered statistically significant.

RESULTS
The median age was 76 [interquartile range (IQR) 60–83] years, 102 male and 66 female. 20 of these had previous SARS-CoV-2 infection.
In 140 patients that received booster dose, Ab were detected after 30 ± 6 days. The response rate was 99.3%. Those who did not have SARS-CoV-2 infection showed an Ab median title of 10 700 BAU/mL (IQR 3482–18 625) while those who had previous infection showed an Ab median title of 18 300 BAU/mL (IQR 1200–37 500) (P &gt;0.05). There was a negative correlation between age and Ab title (P &lt; 0.01). Females showed a higher Ab title than males, both groups were homogeneous for age (P &lt; 0.05).
Ab were detected in all patients who assumed only 2 vaccine doses (mean time after last dose, 121 ± 88 days). In this group, Ab title was higher in previously infected patients (18 500 BAU/mL [IQR 15 800–44 700]) than in those who were not infected [172 BAU/mL (IQR 110–750)] (P &lt; 0.01).
Focusing on patients with previous SARS-CoV-2 infection, 2 vaccine's doses enhanced Ab title more than infection alone [455 BAU/mL (IQR 212–3500)] (P &lt; 0.05). There were no statistically significant differences with two or three doses in Ab title (mean time after last dose 41 ± 24 and 30 ± 6 days, respectively (P &gt;0.05). Lastly, SARS-CoV-2 infection significantly enhanced humoral immunity response independently to time elapsed since infection (P &gt;0.05). The distribution of Ab among patients is detailed in Figure 1.

CONCLUSION
Early response to booster vaccine dose was present in the majority of our HD patients. Ab title was higher in younger and female patients [33]. According to other studies [4], a completed cycle of vaccine (at least 2 doses) was also recommended in patients with a previous SARS-CoV-2 infection because of the decrease of the Ab title in this group of patients. A crucial question remains unsolved: how long vaccine-induced protection will last in HD patients after booster dose?