ABSTRACT
BackgroundTreatment with Rituximab (RTX) in patients with rheumatic diseases (RD) has presented a challenge during the COVID-19 pandemic, as RTX leads to markedly reduced and often undetectable antibody responses after COVID-19 vaccination (1).ObjectivesTo investigate the effect of COVID-19 mRNA revaccination (two doses) on the antibody response in patients with RD who were initial vaccine non-responders. Further, to examine if B-cell levels or T-cell responses before revaccination predicted seroconversion.MethodsFrom a RD cohort (COPANARD) vaccinated with the standard two-dose COVID-19 vaccinations, we enrolled cases without detectable antibody responses (n=17) and controls with detectable antibody response (n=29). Blood donors (n=32) were included as additional controls. Samples were collected before and six weeks after completed revaccination. Total antibodies (abs) and specific IgG, IgA, and IgM against SARS-CoV-2 spike protein, SARS-CoV-2 neutralizing abs, and SARS-CoV-2 reacting CD4+ and CD8+ T-cells were measured before and after revaccination. B-cells (CD19+CD45+) were quantified before revaccination. This study was funded by the Danish Rheumatism Association.ResultsPatient demographics are given in Table 1. Forty-seven percent of cases had detectable total SARS-CoV-2 abs and neutralizing abs after revaccination. However, antibody levels were significantly lower than in controls and blood donors (p<0.008), Figure 1A+B. Revaccination induced an antibody class switch in cases with a decrease in detectable IgM abs (Baseline 11/17, Followup 3/17) and increase in IgG. No significant difference was observed in T-cell responses before and after revaccination between the three groups, Figure 1C. The proportion of cases with detectable CD4+ T cells increased from 69% to 88% (p=0.25), and for CD8+ T cells, the proportion decreased from 88% to 82% (p=1.00). Only 29% of cases had measurable B-cells compared to 100% of controls and blood donors, Figure 1D. Fifty percent of revaccinated cases who seroconverted had measurable B-cells before revaccination, Figure 1D.Univariate logistic regression analysis was performed to analyze if active RTX treatment, the presence of B-cells, or a positive T-cell response prior to revaccination predicted seroconversion of total SARS-CoV-2-abs in the patient cohort. We did not find a significant explanatory effect of either variable in the univariate logistic models, data not shown.Table 1.DemographicsCases Revaccination, n=17Controls Boost, n=29Female sex, no(%)1482%2172%Age, median (IQR)6549 - 706762 - 72Disease duration, years1510 - 18229 - 31Rheumatoid Arthritis/SLE13/410/19None DMARD529%828%Prednisone424%13%Methotrexate741%1241%Hydroxychloroquine212%414%None biologic treatment424%931%Rituximab1271%0TNF-inhibitors16%724%JAK-inhibitors0621%IL-6-inhibitors, Abatacept, Benlysta0724%Previous rituximab treatmentAny rituximab treatment1694%13%RTX within the last 15 months, no1488%0Cumulative total dose, mg134-242Time from RTX to revaccination, months95-1249Figure 1.ConclusionIn conclusion, forty-seven percent of initial non-responders were able to seroconvert after two-dose revaccination. However, plasma concentrations of the antibodies against SARS-COV-2 and the levels of neutralizing capacity remained significantly lower than in immunocompetent blood donors. B-cell levels or T-cell responses before revaccination did not predict seroconversion. Our study suggests that patients with RDs who did not mount a detectable serological response to a COVID-19 mRNA vaccine have a T cell response similar to immunocompetent controls. Future studies should establish the antibody levels that identify RD patients without sufficient protection against SARS-CoV-2 infection.References[1]Troldborg A, et al. Time Since Rituximab Treatment Is Essential for Developing a Humoral Response to COVID-19 mRNA Vaccines in Patients With Rheumatic Diseases. J Rheumatol. 2022.AcknowledgementsThe Danish Rheumatism Association [grant number R203-A7217]. We acknowledge all patients and blood donors contributing to the stud for their invaluable participation. The authors would like to thank Sif Kaas Nielsen and Mads Engelhardt Knudsen, the Laboratory of Molecular Medicine at Rigshospitalet, for their excellent technical assistance in analyzing the samples.Disclosure of InterestsNone Declared.