Tixagevimab/Cilgavimab does not prevent COVID-19 in Patients with Multiple Sclerosis and Related Disorders on B-cell Depleting Therapies

Background Patients with MS and related disorders (pwMSARD) on B-cell depleting treatments have attenuated immune responses to vaccination and were eligible to receive tixagevimab/cilgavimab. Objectives Understand incidence and severity of COVID-19 in pwMSARD on B-cell depleting therapies who received tixagevimab/cilgavimab compared to an untreated group. Methods We conducted a retrospective medical records review of adult pwMSARD on B-cell depleting treatments who received tixagevimab/cilgavimab between 1/2022-1/2023. PwMSARD on B-cell depleting treatments who did not served as a control group (CG). We compared COVID-19 incidence and severity within 6 months of tixagevimab/cilgavimab or rituximab/ocrelizumab infusion for the CG. Results 210 patients were identified, 135 in the treatment group (TG) and 75 in the CG. In the TG, 24 (17.8%) developed COVID-19 compared to 12 (16%) in the CG. There was no difference in the odds of developing COVID-19 in an unadjusted logistic regression model (OR=1.14; 95% CI: 0.53, 2.42; p=0.74) or after adjusting for age and disease duration (OR=1.05; 95% CI: 0.47, 2.37; p=0.91). There was also no difference in COVID-19 severity between groups. Conclusions There was no difference in COVID-19 infection rates or severity in patients with MSARD on B-cell depleting treatments who received tixagevimab/cilgavimab compared to those who remained untreated.