mRNA vaccines against SARS-CoV-2 are remarkably effective. Limited information exists about the incidence of adverse events following immunization (AEFI) with their use. We conducted a prospective observational study including data from 704,003 first-doses recipients; 6536 AEFI were reported, of whom 65.1% had at least one neurologic AEFI ( non-serious 99.6%). Thirty-three serious events were reported; 17 (51.5%) were neurologic (observed frequency, 2.4/100,000 doses). At the time of writing this report, 16/17 cases had been discharged without deaths. Our data suggest that the BNT162b2 mRNA COVID-19 vaccine is safe; its individual and societal benefits outweigh the low percentage of serious neurologic AEFI. This information should help to dissipate hesitancy towards this new vaccine platform.

Vaccines are the most effective strategy to mitigate the global impact of COVID-19. However, vaccine hesitancy is common, particularly among minorities. Guillain-Barré syndrome (GBS) is the most common autoimmune illness of the peripheral nervous system, occurring at an incidence of 1.1/100,000 worldwide. A causal link between mRNA vaccines and GBS has not been previously evaluated. We analyzed a cohort of 3,890,250 Hispanic/Latinx recipients of the BNT162b2 mRNA vaccine (613,780 of whom had already received both doses) for incident GBS occurring within 30 days from vaccine administration. Seven cases of GBS were detected among first-dose recipients, for an observed incidence of 0.18/100,000 administered doses during the prespecified timeframe of 30 days. No cases were reported after second-dose administration. Our data suggest that, among recipients of the BNT162b2 mRNA vaccine, GBS may occur at the expected community-based rate; however, this should be taken with caution as the current incidence of GBS among the unvaccinated population against COVID-19 is still undetermined. We hope that this preliminary data will increase the public perception of safety toward mRNA-based vaccines and reduce vaccine hesitancy.

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Background and objectives:Information on stroke among SARS-CoV-2 vaccines remains scarce. We report stroke incidence as an adverse event following immunization (AEFI) among recipients of 79,399,446 doses of 6 different SARS-CoV-2 vaccines (BNT162b2, ChAdOx1 nCov-19, Gam-COVID-Vac, CoronaVac, Ad5-nCoV, and Ad26.COV2-S) between December 24, 2020, and August 31, 2021, in Mexico.Methods:Retrospective descriptive study analyzing stroke incidence per million doses among hospitalized adult patients (≥18 years) during an 8-month interval. According to the World Health Organization, AEFIs were defined as clinical events occurring within 30 days following immunization and categorized as either non-serious or serious depending on severity, treatment, and hospital admission requirements. Acute ischemic stroke (AIS), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and cerebral venous thrombosis (CVT) cases were collected through a passive epidemiological surveillance system in which local health providers report potential AEFI to the Mexican General Board of Epidemiology. Data were captured using standardized case report formats by an ad-hoc committee appointed by the Mexican Ministry of Health to evaluate potential neurologic AEFI against SARS-COV-2.Results:We included 56 patients (female, 31 [55.5%]) for an overall incidence of 0.71 cases per 1,000,000 administered doses (95% confidence interval [CI] 0.54–0.92); median age was 65 years (interquartile range 55–76); median time from vaccination-to-stroke (of any subtype) was 2 days (interquartile range 1–5); in 27 (48.2%) patients, the event was diagnosed within the first 24 hours following immunization. The most frequent subtype was AIS in 43 patients (75%; 0.54/1,000,000 doses, 95% CI 0.40–0.73) followed by ICH in 9 (16.1%; 0.11/1,000,000 doses, 95% CI 0.06–0.22), and SAH and CVT, each with 2 cases (3.6%; 0.03/1,000,000 doses, 95% CI 0.01–0.09). Overall, the most common risk factors were hypertension in 33 (58.9%) patients and diabetes mellitus in 22 (39.3%); median hospital length of stay was 6 days (IQR 4–13); at discharge, functional outcome was good (modified Rankin Scale of 0–2) in 41.1% of patients; in-hospital mortality rate was 21.4%.Discussion:Stroke is an exceedingly rare AEFI against SARS-CoV-2. Pre-existing stroke risk factors were identified in most patients. Further research is needed to evaluate causal associations between SARS-COV-2 vaccines and stroke.