Risk of Stroke after Vaccination against COVID19 in Patients with Moyamoya Disease: Nationwide Cohort Observational Study

The safety and efficacy of coronavirus disease 2019 (COVID-19) vaccination in patients diagnosed with Moyamoya disease (MMD) have not been established. Using National Health Insurance Service data, this study analyzed the occurrence of stroke-related events and mortality following COVID-19 vaccination among patients diagnosed with MMD from 2008 to 2020. Among 10,297 MMD patients, 296 (2.9%) experienced stroke-related events and 175 (1.7%) died in 2021. Significant risk factors for events included ages 50–59 (Odds Ratio [OR] 3.29; P = 0.022) and 60 or above (OR 5.20; P = 0.001), low BMI (OR 2.00; P = 0.011), previous stroke (OR 1.96; P < 0.001), and COVID-19 infection (OR 2.28; P = 0.034). Female (OR 0.64; P = 0.011), revascularization surgery (RS) (OR 0.38; P < 0.001), and vaccination (OR 0.17; P < 0.001) were protective. For mortality, significant risks were age over 60 (OR 7.09; P = 0.008), low BMI (OR 3.87; P = 0.001), and prior stroke (OR 1.74; p = 0.004), while being female, RS (OR 0.41; P = 0.022), and vaccination (OR 0.12; P < 0.001) were preventive. mRNA vaccines were more effective than vector vaccines in preventing events, mortality, and COVID19 infections. COVID-19 vaccination significantly reduces stroke-related events and mortality in MMD patients, with mRNA vaccines being more effective. COVID-19 infection raises the risk of events, underscoring the benefit of vaccination.