COVID-19 vaccination in patients with multiple sclerosis: Safety and humoral efficacy of the third booster dose

•The third dose resulted in adverse events profile similar to that following the first and second doses.•No increased risk for relapse activity following the third vaccine dose was observed within a follow-up of 2 months.•Paired kinetics of anti-spike IgG titers revealed a 21-fold increase in up to 3 months following the third dose.•This finding held true both in untreated and in vaccination–safe DMTs treated MS patients.