Investigation into Potential Link Between Pfizer COVID-19 Booster and Ischemic Stroke

Strategic Insights -

Researchers at the Centers for Disease Control and Prevention (CDC) have been investigating a potential connection between the administration of the Pfizer novel coronavirus disease-2019 (COVID-19) bivalent vaccine booster and ischemic stroke (IS) in older adults. A retrospective cohort study was conducted to compare the hazard of IS among patients aged 65 years or over who received the Pfizer bivalent, Moderna bivalent, or Pfizer/Moderna monovalent COVID-19 booster vaccine. The study used data from over 90 million unique patients in the United States, collected from TriNetX, a cloud-based analytics platform.

Key Takeaways:

  • The study found no significant difference in the hazard of IS encounters between the Pfizer bivalent and Moderna bivalent cohorts at 1-21- or 22-42-days post-administration.
  • The hazard for IS was lower in the Pfizer bivalent cohort than in the Pfizer/Moderna monovalent cohort at both timepoints.
  • The study included 4,267 patients in the Pfizer bivalent cohort, with an average age of 73.7 years (44.43% male, 76.59% white).
  • The majority of the study population (76.59%) was white, which may impact the generalizability of the findings to other racial and ethnic groups.
  • The study's results suggest that older adults administered the Pfizer bivalent booster may have a lower hazard for IS encounters compared to those administered the Pfizer/Moderna monovalent boosters.
  • The preprint has not been peer-reviewed, and the study's findings should be interpreted with caution.

Statistics:

  • 43,216 patients received the Pfizer bivalent booster vaccine.
  • 4,267 patients received the Moderna bivalent booster vaccine.
  • 100,583 patients received the Pfizer/Moderna monovalent booster vaccine.
  • The Pfizer bivalent cohort included patients with an average age of 73.7 years (44.43% male, 76.59% white).
  • The hazard ratio (HR) for IS encounters between the Pfizer bivalent and Moderna bivalent cohorts at 1-21- and 22-42-days post-administration was 0.59 (0.31, 1.11) and 0.73 (0.33, 1.60), respectively.
  • The hazard ratio (HR) for IS encounters between the Pfizer bivalent and Pfizer/Moderna monovalent cohorts at 1-21- and 22-42-days post-administration was 0.24 (0.19, 0.29) and 0.25 (0.20, 0.31), respectively.

Sources:

  • medrxiv.org/content/10.1101/2023.02.11.23285801v1 (preprint abstract)