LAUSR

In “Stroke Among SARS-CoV-2 Vaccine Recipients in Mexico: A Nationwide Descriptive Study,” López-Mena et al. reported that the incidence of stroke within 30 days of immunization was 0.71 cases per 1,000,000 doses of SARS-CoV-2 vaccine in Mexico from December 24, 2020, to August 31, 2021, based on a passive epidemiologic surveillance system. The authors concluded that stroke is an exceedingly rare adverse event after immunization. Taccetta commented that (1) the use of a passive surveillance system likely led to underreported incidence of postimmunization stroke and (2) the 30-day window likely missed some cases of postimmunization stroke. For instance, they note that vaccine-induced thrombocytopenia is defined based on a 42-day window. García-Grimshaw et al. agreed that passive surveillance cannot detect true incidence and that their findings reflect observed incidence of stroke. They also agreed that some postimmunization adverse events are identified based on a 42-day window but noted that the 30-day window was selected based on the World Health Organization's operational definition for surveillance of postimmunization adverse events in Mexico during the study period. Stoiloudis et al. reported a case of stroke after SARS-CoV-2 vaccination and hypothesized that elevated temperature postvaccination may increase the risk of stroke. Stoiloudis et al. and García-Grimshaw et al. agree that additional research is needed into the mechanism of postvaccination stroke.