ABSTRACT
BACKGROUND: Data are sparse regarding the safety of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in patients with multiple sclerosis (MS). OBJECTIVE: To estimate (1) the pooled proportion of MS patients experiencing relapse among vaccine recipients; (2) the rate of transient neurological worsening, adverse events, and serious adverse events; (3) the previous outcomes of interest for different SARS-CoV-2 vaccine types. METHODS: Systematic review and meta-analysis of pharmacovigilance registries and observational studies. RESULTS: Nineteen observational studies comprising 14,755 MS patients who received 23,088 doses of COVID-19 vaccines were included. Mean age was 43.3 years (95% confidence interval (CI): 40-46.6); relapsing-remitting, secondary-progressive, primary-progressive MS and clinically isolated syndrome were diagnosed in 82.6% (95% CI: 73.9-89.8), 12.6% (95% CI: 6.3-20.8), 6.7% (95% CI: 4.2-9.9), and 2.9% (95% CI: 1-5.9) of cases, respectively. The pooled proportion of MS patients experiencing relapse at a mean time interval of 20 days (95% CI: 12-28.2) from vaccination was 1.9% (95% CI: 1.3%-2.6%; I2 = 78%), with the relapse risk being independent of the type of administered SARS-CoV-2-vaccine (p for subgroup differences = 0.7 for messenger RNA (mRNA), inactivated virus, and adenovector-based vaccines). After vaccination, transient neurological worsening was observed in 4.8% (95% CI: 2.3%-8.1%) of patients. Adverse events and serious adverse events were reported in 52.8% (95% CI: 46.7%-58.8%) and 0.1% (95% CI: 0%-0.2%) of vaccinations, respectively. CONCLUSION: COVID-19 vaccination does not appear to increase the risk of relapse and serious adverse events in MS. Weighted against the risks of SARS-CoV-2-related complications and MS exacerbations, these safety data provide compelling pro-vaccination arguments for MS patients.