No link between mRNA SARS-CoV-2 vaccine and stroke

People who receive an mRNA SARS-CoV-2 vaccine do not appear to be at increased risk of stroke within the first 28 days of immunization, as shown in a large study.

The registry-based cohort study involved all adult residents in Norway on 27 December 2020. Individual-level data were linked to COVID-19 vaccination, positive SARS-CoV-2 test, hospital admissions, cause of death, healthcare worker status, and nursing home resident status extracted from the Emergency Preparedness Register for COVID-19 in Norway.

All participants were followed for the incidence of intracerebral bleeding, ischaemic stroke, and subarachnoid haemorrhage within the first 28 days after the first/second or third dose of an mRNA SARS-CoV-2 vaccine until 24 January 2022.

The analysis included 4,139,888 participants (49.8 percent women, 6.7 percent were ≥80 years of age). During the first 28 days after vaccination, 2,104 people had incident stroke (82 percent ischaemic stroke, 13 percent intracerebral haemorrhage, and 5 percent subarachnoid haemorrhage).

Cox proportional hazards analysis showed no association between immunization and the risk of stroke. The corresponding adjusted hazard ratios associated with the first/second and the third mRNA SARS-CoV-2 vaccine doses were 0.92 (95 percent confidence interval [CI], 0.85–1.00) and 0.89 (95 percent CI, 0.73–1.08) for ischaemic stroke, 0.81 (95 percent CI, 0.67–0.98) and 1.05 (95 percent CI, 0.64–1.71) for intracerebral haemorrhage, and 0.64 (95 percent CI, 0.46–0.87) and 1.12 (95 percent CI, 0.57–2.19) for subarachnoid haemorrhage, respectively.