Risk for Myocardial Infarction, Stroke, and Pulmonary Embolism Following COVID-19 Vaccines in Adults Younger Than 75 Years in France

Abstract

Background: The BNT162b2 (Pfizer-BioNTech) vaccine has been shown to be safe with regard to risk for severe cardiovascular events (such as myocardial infarction [MI], pulmonary embolism [PE], and stroke) in persons aged 75 years or older. Less is known about the safety of other COVID-19 vaccines or outcomes in younger populations.

Objective: To assess short-term risk for severe cardiovascular events (excluding myocarditis and pericarditis) after COVID-19 vaccination in France's 46.5 million adults younger than 75 years.

Design: Self-controlled case series method adapted to event-dependent exposure and high event-related mortality.

Setting: France, 27 December 2020 to 20 July 2021.

Patients: All adults younger than 75 years hospitalized for PE, acute MI, hemorrhagic stroke, or ischemic stroke (n = 73 325 total events).

Measurements: Linkage between the French National Health Data System and COVID-19 vaccine databases enabled identification of hospitalizations for cardiovascular events (MI, PE, or stroke) and receipt of a first or second dose of the Pfizer-BioNTech, mRNA-1273 (Moderna), Ad26.COV2.S (Janssen), or ChAdOx1 nCoV-19 (Oxford-AstraZeneca) vaccine. The relative incidence (RI) of each cardiovascular event was estimated in the 3 weeks after vaccination compared with other periods, with adjustment for temporality (7-day periods).

Results: No association was found between the Pfizer-BioNTech or Moderna vaccine and severe cardiovascular events. The first dose of the Oxford-AstraZeneca vaccine was associated with acute MI and PE in the second week after vaccination (RI, 1.29 [95% CI, 1.11 to 1.51] and 1.41 [CI, 1.13 to 1.75], respectively). An association with MI in the second week after a single dose of the Janssen vaccine could not be ruled out (RI, 1.75 [CI, 1.16 to 2.62]).

Limitations: It was not possible to ascertain the relative timing of injection and cardiovascular events on the day of vaccination. Outpatient deaths related to cardiovascular events were not included.

Conclusion: In persons aged 18 to 74 years, adenoviral-based vaccines may be associated with increased incidence of MI and PE. No association between mRNA-based vaccines and the cardiovascular events studied was observed.

Primary funding source: None.

Visual Abstract.. Risk for MI, Stroke, and PE Following COVID-19 Vaccines.

Severe cardiovascular events (myocardial infarction [MI], pulmonary embolism [PE], and stroke) have been reported after COVID-19 vaccination. In this French registry-based analysis of adults younger than 75 years, administration of the Pfizer–BioNTech or Moderna mRNA vaccine was not associated with increased risk for MI, PE, or stroke. However, recipients of the Oxford–AstraZeneca vaccine had greater risk for MI and PE in the second week after vaccination. A similar association for the Janssen adenoviral-based vaccine could not be ruled out.

Figure.. Conceptual diagram of the adaptation of the self-controlled case series method used.

Further details are provided in the Supplement. When the effect of the first vaccine dose is estimated, second doses (should they occur) are suppressed, but counts of cardiovascular events that occur during such second-dose exposure periods are adjusted to account for the fact that second doses were suppressed. This is done by replacing the event count n with n/RI2, where RI2 is the effect of the second dose. Second doses are suppressed when effects of the first dose are estimated because the presence and timing of such second doses may be affected by the event occurring after the first dose. See also reference 20.