HUMORAL IMMUNE RESPONSE to SARS-COV-2 VACCINE in RITUXIMAB-TREATED PATIENTS

ABSTRACT

Background: Vaccination against SARS-CoV-2 has shown efficacy and safety in patients with chronic infammatory rheumatic disease, similar to the general population. However, in patients treated with rituximab (RTX) it is known that usually have a lower vaccination response rate (1-2), and recent studies suggest that it also happens with the new SARS-CoV 2 vaccine (3), which entails an increased risk of hospitalization and mortality in this specifc group of patients. Objectives: To describe humoral immune response to SARS-CoV-2 vaccine in rituximab-treated patients after one and six months from the vaccination, and study if there is any other factor associated with a lower response rate. Methods: Prospective analysis of a cohort of patients treated with RTX who received the SARS-CoV-2 vaccine between the months of April and October 2021. Demographic and medical data were collected through electronic medical records. Blood tests and serologies with levels of antibodies against SARS-CoV-2 were performed one and six months after having received the vaccine against SARS-CoV-2. The administration of a booster dose of the vaccine was recorded. A descriptive and statistical analysis of the data was carried out using the SPSS program. Results: From a cohort of 41 patients, of whom 81,4% were women with a mean age of 56 (13,4 SD) years, vaccine response rate was only 36,7% after a 6-month follow-up. The 88,4% of them received a booster dose of the vaccine, but this failed to produce a vaccine response in any of the patients who had not developed it with the previous ones. One patient became infected after receiving one dose of the vaccine and failed to develop a serological response either. Hypogammaglobulinemia was associated with a statistically signifcant lower probability of vaccine response (p=0,04). A trend of lower vaccination response rate was observed in patients who had received the last cycle of RTX in the 6 months prior to vaccination (p=0,058). In addition, the antibody levels developed one month after vaccination were statistically signifcantly correlated with the time between the last RTX cycle and vaccination (p=0,014) and also with CD19 B cells levels prior to vaccination (p<0,001);however, there was no correlation with the antibody levels detected at the 6-months serology. No statistically signifcant differences were found in relation to the number of previous cycles of RTX, concomitant treatment with synthetic disease-modifying drugs (DMARDs) or corticosteroids. Conclusion: In our sample, after a 6-month follow-up only 36,9% achieved a vaccine response against SARS-CoV-2, which did not improve despite the administration of a booster dose. Hypogammaglobulinemia, the time between the last RTX cycle and vaccination (at least 6 months), and previous CD19 B cells levels signifcantly influenced in the development of a humoral response to the vaccine.