Study examines cardiovascular safety of Pfizer bivalent COVID-19 vaccine

Concern about the safety of the Pfizer/BioNTech bivalent COVID-19 vaccine arose in January 2023. At that time, the Vaccine Safety Datalink of the U.S. Centers for Disease Control and Prevention alerted the public about a possible increased risk of ischemic stroke within the 21 days after receiving the Pfizer bivalent booster in older persons (≥ 65 years). This safety issue was considered a “preliminary signal,” as it was not identified by other safety surveillance systems or in other countries. In addition, there was no evidence of a similar safety issue with the bivalent COVID-19 vaccine booster produced by Moderna. To further investigate this issue, French investigators assessed whether the risk of stroke, acute myocardial infarction or pulmonary embolism differed after receipt of the Pfizer COVID-19 bivalent booster compared with the Pfizer monovalent booster. The population-based study used comprehensive data from the French National Health Data System linked to the national COVID-19 vaccination database. It included all persons who were 50 years of age or older and who had received a booster dose of the Pfizer vaccine between October 6 and November 9, 2022 (the only time period when both the Pfizer monovalent and bivalent boosters were being administered in France). Individuals who received another type of COVID-19 booster, such as the Moderna Spikevax bivalent vaccine or the Spikevax original vaccine, were excluded from the study. For each day during the study period, each recipient of the Pfizer monovalent vaccine was matched with up to five randomly sampled recipients of the Pfizer bivalent vaccine on the same day. Recipients were followed for 21 days after vaccination and monitored for the occurrence of ischemic stroke, hemorrhagic stroke, myocardial infarction or pulmonary embolism. Results showed the following: The study included a total of 470,962 vaccine recipients (mean age, 72.6 years). Of these, 97,234 (20.6%) received the Pfizer monovalent booster and 373,728 (79.4%) received the Pfizer bivalent booster. Sociodemographic and health-status characteristics were well balanced between the two groups. At 21 days after the booster dose, no evidence was found of an increased risk of cardiovascular events among the recipients of the Pfizer bivalent vaccine compared with recipients of the Pfizer monovalent vaccine. The evaluated events included ischemic stroke (hazard ratio [HR], 0.86; 95% confidence interval [CI], 0.58–1.27), hemorrhagic stroke (HR, 0.86; 95% CI, 0.46–1.61), myocardial infarction (HR, 0.92; 95% CI, 0.62–1.36), pulmonary embolism (HR, 0.83; 95% CI, 0.49–1.40), and all four events combined (HR, 0.87; 95% CI, 0.69–1.09). The authors maintain that their results provide reassurance regarding the cardiovascular safety of continued use of the Pfizer bivalent COVID-19 vaccine. References 1. Jabagi MJ, Bertrand M, Botton J, et al. Stroke, myocardial infarction, and pulmonary embolism after bivalent booster. NEJM 2023. Published online March 29, 2023. (accessed April 3, 2023). 2. Jabagi MJ, Bertrand M, Botton J, et al. Stroke, myocardial infarction, and pulmonary embolism after bivalent booster. Supplementary appendix. NEJM 2023. Published online March 29, 2023. (accessed April 3, 2023).

Study examines cardiovascular safety of Pfizer bivalent COVID-19 vaccine

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