Bivalent COMIRNATY vaccine versus monovalent COMIRNATY: no increase in cardiovascular risk

New reassuring data

LThe EPI-PHARE Scientific Interest Group (GIS) shared the results of a new pharmacoepidemiology survey [1, 2]. Its objective was to compare the risk of a serious cardiovascular event associated with one of the COMIRNATY bivalent vaccines (cf. Box 1), as a reminder in people aged 50 and over, to that of its monovalent version.

The French study, conducted according to the usual method using French data from the National Health Data System (SNDS), was published in the New England Journal of Medicine (NEJM) [3].

A doubt expressed across the Atlantic

This French study was initiated following a safety signal issued in January 2023 in the United States by the Food and Drug Administration (FDA) and the Vaccine Safety Datalink of the Centers for Disease Control and Prevention North Americans. US authorities have mentioned a potential increased risk of ischemic cerebrovascular accident (CVA) within 21 days of administration of the bivalent COMIRNATY vaccine in people aged 65 and over.

A study of more than 400,000 people

The cardiac adverse effects mentioned in the marketing authorization (MA) for COMIRNATY are myocarditis and pericarditis (very rare frequency). In addition to these legal notices, several studies, including those of EPI-PHARE, have been carried out to assess the risk of certain cardiovascular events associated with mRNA vaccines, excluding myocarditis and pericarditis:

  • acute myocardial infarction;
  • Ischemic or hemorrhagic stroke;
  • pulmonary embolism.

After comparing vaccinated and unvaccinated populations, these EPI-PHARE studies published on this subject did not show an increase in this risk in the event of exposure to an mRNA vaccine (cf. our article of January 20, 2022).

However, this work focused only on monovalent forms of mRNA vaccine. The new EPI-PHARE study recently published includes bivalent vaccines used as a booster vaccine.

A total of 470,962 people were included:

  • 97,234 (20.6%) in the monovalent COMIRNATY vaccine group;
  • 373,728 (79.4%) in the group of one of the bivalent vaccines.

The authors matched each patient who received the monovalent vaccine to a maximum of five people who received the bivalent vaccine on the same day (matching by day of administration).

No increased cardiovascular risk with bivalent COMIRNATY

The results do not show an increased risk of cardiovascular event, whether it is a separate risk of ischemic or hemorrhagic stroke, myocardial infarction, pulmonary embolism, or a combined risk. of these 4 events, within 21 days of administration of the bivalent COMIRNATY vaccine compared to the monovalent vaccine (cf. Box 2). “The continued use of these bivalent mRNA vaccines once morest Covid-19 is thus supported by these reassuring results”conclude the authors.

Box 2 – Results of the EPI-PHARE study: evaluation of the risk of a cardiovascular event associated with the COMIRNATY bivalent vaccine
  • Ischemic stroke (n=148; Hazard Ratio weighted (wHR): 0.9 ; IC95%: 0.6-1.3) ;
  • Hemorrhagic stroke (n = 57; wHR, 0.9; 95% CI: 0.5-1.6);
  • myocardial infarction (n=151; wHR, 0.9; 95% CI: 0.6-1.4);
  • pulmonary embolism (n = 84; wHR, 0.8; 95% CI: 0.5-1.4);
  • the four events combined (n=439; wHR, 0.9; 95% CI: 0.7-1.1).

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