Is Stroke a Common Adverse Event Following COVID-19 Vaccination?

Senior man having a stroke/heart attack
In a retrospective descriptive study, researchers analyzed the occurrence of stroke per million doses of the COVID-19 vaccines among adult patients hospitalized during an 8-month period.

Among SARS-CoV-2 vaccine recipients in Mexico, less than 1 in a 1,000,000 reported incidence of stroke following immunization, according to study findings published in Neurology.

While necessity brought multiple SARS-CoV-2 vaccines to market, phase 3 clinical trials failed to thoroughly examine potential side effects. Health organizations around the world are forced to detect and assess potential adverse events following immunization (AEFI) for themselves. In the US alone, as of March 2, 2021, approximately 182 AEFIs per 1,000,000 doses were reported (non-serious and serious), that included 17 stroke cases. The Mexican Ministry of Health granted emergency approval for the use of SARS-CoV-2 vaccines as of December 24, 2020. Researchers reported on the occurrence of stroke AEFI following SARS-CoV-2 vaccination in Mexico.

To accomplish this, they conducted a retrospective descriptive study among people in Mexico who received 79,399,446 doses of the 6 vaccines approved for emergency use for SARS-CoV-2 by the Mexican Ministry of Health between December 24, 2020 and August 31, 2021: BNT162b2 (Pfizer-BioNTech), ChAdOx1 nCov-19 (AstraZeneca-Oxford), Gam-COVID-Vac (Sputnik V), CoronaVac (Sinovac), Ad5-nCoV (CanSino), and Ad26.CoV2-S (Janssen-Johnson & Johnson) for adult patients (aged 18 years and older) subsequently hospitalized within 30 days of immunization for acute ischemic stroke (AIS), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and cerebral venous thrombosis (CVT).

They found 56 patients (31 female; median aged 65 years [IQR 55-76]; time from inoculation-to-stroke of any type, median 2 days [IQR 1-5], [for 27 patients, the AEFI was diagnosed is less than a day following inoculation]) showing an incidence rate of 0.71 cases per 1,000,000 doses (95% CI, 0.54-0.92). Of the stroke subtypes, 43 patients had AIS (75%; 0.54/1,000,000 doses, 95% CI, 0.40-0.73); 9 patients had ICH (16.1%; 0.11/1,000,000 doses, 95%CI, 0.06–0.22); 2 patients each had SAH or CVT (3.6%; 0.03/1,000,000 doses, 95%CI, 0.01–0.09). Median time in the hospital was 6 days (IQR 4-13), and the mortality rate was 21.4%. Outcome was good for 41.1% of patients discharged. Researchers determined the greatest risk factors were hypertension (58.9% of the patients) and diabetes mellitus (39.3%).

The researchers reported several study limitations, including: 1) The descriptive nature and lack of statistical power to establish causality; 2) Selection bias; 3) Underdiagnosed and unreported stroke in local and rural settings; and 4) The nature of a passive surveillance study.

Researchers said, “Stroke is an exceedingly rare AEFI against SARS-COV-2.” They did acknowledge the presence of pre-existing stroke risk factors in most patients. Overall, further research is warranted to assess the associations between SARS-CoV-2 vaccines and incidence of stroke.


López-Mena D, Garcí-A-Grimshaw M, Saldivar-Dávila S, et al. Stroke Among SARS-CoV-2 Vaccine Recipients in Mexico: A Nationwide Descriptive Study. Neurology. Published online March 11, 2022. doi:10.1212/WNL.0000000000200388