Acute Arterial Ischemic Stroke Following COVID-19 Vaccination

Acute arterial-ischemic-stroke (AIS) has been reported as a rare adverse-event following COVID-19-vaccination with mRNA or viral-vector vaccines. However, data are sparse regarding the risk of post-vaccination AIS and its potential association with thrombotic-thrombocytopenia-syndrome (TTS).A systematic review and meta-analysis of randomized-controlled clinical trials (RCTs), pharmacovigilance registries, registry-based studies, observational cohorts and case-series was performed with the aim to calculate: (1) the pooled proportion of patients presenting with AIS following COVID-19-vaccination; (2) the prevalence of AIS after mRNA and vector-based vaccination; (3) the proportion of TTS among post-vaccination AIS-cases. Patient characteristics were assessed as secondary outcomes.Two RCTs, three cohort and eleven registry-based studies comprising 17,481 AIS-cases among 782,989,363 COVID-19-vaccinations were included in the meta-analysis. The pooled proportion of AIS following exposure to any COVID-19-vaccine type was 4.7 cases per 100,000 vaccinations (95%CI:2.2-8.1; I2=99.9%). The pooled proportion of AIS following mRNA-vaccination (9.2 cases per 100,000 vaccinations; 95%CI: 2.5-19.3; I2=99.9%) did not differ compared to adenovirus-based-vaccination (2.9 cases per 100,000 vaccinations; 95%CI: 0.3-7.8; I2=99.9%). No differences regarding demographics were disclosed between patients with AIS following mRNA- or vector-based vaccination. The pooled proportion of TTS among post-vaccination AIS-cases was 3.1% (95%CI: 0.7-7.2%; I2=78.8%).The pooled proportion of AIS following COVID-19 vaccination is comparable to the prevalence of AIS in the general population and much lower than the AIS prevalence among SARS-CoV-2-infected patients. TTS is very uncommonly reported in patients with AIS following COVID-19 vaccination.