Safety and effectiveness outcomes in Multiple Sclerosis (MS) patients receiving different disease-modifying therapies (DMT) and different types of vaccines against SARS-CoV-2 are limited. Growing evidence coming mainly from Israel, Europe and North America using mRNA and adenoviral vector vaccines has been published.
To assess the safety and humoral response of inactivated virus and mRNA vaccines against SARS-CoV-2 in patients with MS.
Ongoing, multicentric, prospective, observational study performed between February and September 2021. Humoral response (antibodies against spike-1 protein) was determined at least 4 weeks after the complete schedule of anti-SARS-CoV-2 vaccines. Categorical outcome (positive/negative) and total antibody titres were recorded. Adverse events supposedly attributable to vaccination (AESAV) were collected.
178 patients, 68% women, mean age 39.7 ± 11.2 years, 123 received inactivated (Coronavac-Sinovac), 51 mRNA (Pfizer-BioNtech), and 4 adenoviral vector vaccines (CanSino n = 2, Jonhson&Johnson-Jannsen n = 1, Oxford-AstraZeneca n = 1). Six patients had a history of COVID-19 before vaccination. Overall humoral response was observed in 66.9% (62.6% inactivated vs. 78.4% mRNA, p = 0.04). Positive anti-S1-antibodies were observed in 100% of patients with no DMT (n = 3), 100% with interferon/glatiramer-acetate (n = 11), 100% with teriflunomide/dimethyl-fumarate (n = 16), 100% with natalizumab (n = 10), 100% with alemtuzumab (n = 8), 90% with cladribine (n = 10), and 88% with fingolimod (n = 17), while 43% of patients receiving antiCD20 (n = 99) were positive (38% inactivated vaccine vs. 59% mRNA vaccine, p = 0.05). In the multivariate analysis including antiCD20 patients, the predictors for a positive humoral response were receiving the mRNA vaccine (OR 8.11 (1.79-36.8), p = 0.007) and a lower number of total infusions (OR 0.44 (0.27-0.74) p = 0.002. The most frequent AESAV was local pain (14%), with 4 (2.2%) patients experiencing mild-moderate relapses within 8 weeks of first vaccination compared to 11 relapses (6.2%) within the 8 weeks before vaccination (Chi-squared 3.41, p = 0.06).
A higher humoral response rate was observed using the mRNA compared to the inactivated vaccine, while patients using antiCD20 had a significantly lower response rate, and patients using antiCD20 and fingolimod had lower antibody titres. In this MS patient cohort, inactivated and mRNA vaccines against SARS-CoV-2 appear to be safe, with no increase in relapse rate. This information may help guidelines including booster shots and types of vaccines in selected populations.

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