Background and Aims: The National Multiple Sclerosis Society and other expert organizations recommended that all patients with multiple sclerosis (MS) should be vaccinated against COVID-19. However, the effect of disease-modifying therapies (DMTs) on the efficacy to mount an appropriate immune response is unknown. We aimed to characterize humoral immunity in mRNA-COVID-19 MS vaccinees treated with high-efficacy DMTs. Methods: We measured SARS-CoV-2 IgG response using anti-spike protein-based serology (EUROIMMUN) in 125 MS patients vaccinated with BNT162b2-COVID-19 vaccine 1 month after the second dose. Patients were either untreated or under treatment with fingolimod, cladribine, or ocrelizumab. A group of healthy subjects similarly vaccinated served as control. The percent of subjects that developed protective antibodies, the titer, and the time from the last dosing were evaluated. Results: Protective humoral immunity of 97.9%, 100%, 100%, 22.7%, and 3.8%, was observed in COVID-19 vaccinated healthy subjects ( N = 47), untreated MS patients ( N = 32), and MS patients treated with cladribine ( N = 23), ocrelizumab ( N = 44), and fingolimod ( N = 26), respectively. SARS-CoV-2 IgG antibody titer was high in healthy subjects, untreated MS patients, and MS patients under cladribine treatment, within 29.5–55 days after the second vaccine dose. Only 22.7% of patients treated with ocrelizumab developed humoral IgG response irrespective to normal absolute lymphocyte count. Most fingolimod-treated MS patients had very low lymphocyte count and failed to develop SARS-COV-2 antibodies. Age, disease duration, and time from the last dosing did not affect humoral response to COVID-19 vaccination. Conclusions: Cladribine treatment does not impair humoral response to COVID-19 vaccination. We recommend postponing ocrelizumab treatment in MS patients willing to be vaccinated as a protective humoral response can be expected only in some. We do not recommend vaccinating MS patients treated with fingolimod as a protective humoral response is not expected.

Background: Since vaccination against coronavirus disease 2019 (COVID-19) became available, risks related to vaccinating patients with multiple sclerosis (MS) need to be carefully assessed. Objective: Characterize safety and occurrence of immediate relapses following COVID-19 vaccination in a large cohort of MS patients. Methods: We assessed the safety of BNT162b2 COVID-19 vaccination in adult MS patients. Results: Between 20 December 2020 and 25 January 2021, 555 MS patients received the first dose of BNT162b2 vaccine and 435 received the second dose. There were three cases of COVID-19 infection encountered after the first dose. Safety profile of COVID-19 vaccine was characterized by pain at the injection site, fatigue, and headache. No increased risk of relapse activity was noted over a median follow-up of 20 and 38 days after first and second vaccine doses, respectively. The rate of patients with acute relapse was 2.1% and 1.6% following the first and second doses, respectively, similar to the rate in non-vaccinating patients during the corresponding period. Mild increase in the rate of adverse events was noted in younger patients (18–55 years), among patients with lower disability (Expanded Disability Status Scale (EDSS) ⩽3.0), and in patients treated with immunomodulatory drugs. Conclusion: COVID-19 BNT162b2 vaccine proved safe for MS patients. No increased risk of relapse activity was noted.

Acute exacerbations may complicate the course of pregnancy and the postpartum period in patients with relapsing-remitting multiple sclerosis (RRMS). To evaluate relapse rate and the effect of immunomodulatory treatment with intravenous immunoglobulin (IVIg) during pregnancy and the postpartum period we retrospectively analysed the data of 108 pregnant RRMS patients. Group I patients were not treated, Group II patients were treated with IVIg 0.4 g/kg body weight/day for 5 consecutive days within the first week after delivery with additional booster doses of 0.4 g/kg body weight/day at 6 and 12 weeks postpartum (defined as 12 weeks after labor), and Group III patients were treated continuously with IVIg during gestation and the postpartum period (0.4 g/kg body weight/day for 5 consecutive days within the 6-8 weeks of gestation with additional booster doses of 0.4 g/kg body weight/day once every 6 weeks until 12 weeks postpartum). All patients underwent antenatal care and fetal ultrasonographic surveillance examinations. Relapse rate per woman per year during the pregnancy and the postpartum period as well as neonatal outcome data and IVIg related adverse events were analysed. Relapse rate per woman per year for patients treated with IVIg for the whole pregnancy and postpartum period (Group III, N = 28) compared with the untreated Group I patients (N = 39) were as follows: first trimester 0.43 vs. 0.72, second trimester 0.15 vs. 0.61, third trimester 0.0 vs. 0.41, and postpartum period 0.28 vs.1.33 (p < 0.05). Patients treated with IVIg only during the postpartum period (Group II, N = 41) also showed a decrease in relapse rate compared with untreated Group I patients, 0.58 vs. 1.33 (p = 0.012). The mean maternal age, disease duration, gestational age at delivery and fetal delivery weight did not significantly differ between the three groups. Mode of delivery, obstetrical complications, the use of epidural analgesia and breast-feeding, did not affect postpartum relapse rate. No severe adverse events were associated with IVIg treatment either during the pregnancy or postpartum period for the patients and newborns.We conclude that in RRMS patients IVIg treatment could be considered as an optional treatment to reduce the incidence of pregnancy and postpartum-related relapses. Further randomized double-blind studies are needed to confirm our findings.