According to results of a population-based cohort study, receipt of a varicella-containing vaccine is not associated with an increased risk of arterial ischemic stroke (AIS) in pediatric patients.

In this retrospective analysis, the study authors set out to determine the risk of AIS following administration of a varicella-containing vaccine. Data from a central immunization repository was used to identify pediatric patients born between January 1, 2006 and December 31, 2013, in Alberta, Canada. The study authors then utilized hospital discharge abstract data to identify any patients that were subsequently diagnosed with AIS.

The study authors explained, “A Cox proportional hazard model assessed the risk of AIS in the 12 months following vaccination for children receiving a varicella vaccine between 11 and 23 months of age, as compared to non-vaccinated children.” 

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Of the 368,992 children included in the study, 325,729 were found to have received a varicella-containing vaccine. The study authors reported that the rate of AIS in the 12 months following vaccination was 7.8 per 100,000 person-years at risk (95% CI: 4.8, 10.9) in patients who received the vaccine versus 6.8 (95% CI: 1.3, 12.2) in those who did not. “The adjusted Hazard Ratio for the risk of AIS, controlling for other AIS risk factors, in vaccinated children as compared to non-vaccinated children was 1.6 (95% CI 0.7–3.7) in the 12 months following vaccination and 1.7 (95% CI 0.5–4.9) in the 30 days following vaccination,” the study authors added.

In pediatric patients, administration of a varicella-containing vaccine does not increase the risk of AIS. “This population-based cohort study provides reassurance to parents and clinicians regarding the safety of varicella vaccination,” the study authors concluded.


MacDonald SE, Dover DC, Hill MD, Kirton A, Simmonds KA, Svenso LW. Is varicella vaccination associated with pediatric arterial ischemic stroke? A population-based cohort study. Vaccine. In print.