In addition to cardiac events, another life-threatening side effect has been associated with the Pfizer-BioNTech vaccine. When is the risk period? Does the flu shot play any role in these events? What actions should we take to better protect ourselves?
Summary of Key Facts
- An increased risk of stroke events has been identified with the Pfizer COVID-19 bivalent vaccine, according to a joint statement from the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA).
- The onset time in people aged 65 years and older was 1–21 days after the booster, with a significant cluster of events observed 11–21 days after the booster.
- Sixty-four percent had received the flu vaccine on the same day as the COVID-19 booster.
- The bivalent booster contains the code of the spike protein, contributing to the increased risk of blood clots. High-risk people should avoid the boosters.
- Solution: Remember the five “suddens” of stroke warning signs.
- Advice on preventing other risk factors of stroke is also provided in this paper.
On Jan. 13, 2023, the FDA and CDC issued a joint statement that a new “safety signal” for ischemic stroke had been detected in one of the agency’s vaccine safety surveillance systems.
The statement read, in part: “CDC’s Vaccine Safety Datalink (VSD), a near real-time surveillance system, met the statistical criteria to prompt additional investigation into whether there was a safety concern for ischemic stroke in people ages 65 and older who received the Pfizer-BioNTech COVID-19 vaccine bivalent.”
The VSD system monitors the electronic health records of 12.5 million Americans served by nine integrated health systems.
The CDC stated that no other safety databases had detected this signal (including the Medicare and Veterans Affairs data sets). Pfizer released a statement that it had not detected this signal in its databases, and no other countries have found a similar signal in their monitoring systems.
The clot risk appears to be greater on days 11–21 after receiving the booster, especially for those who received a high-dose or adjuvant flu vaccine on the same day.
A follow-up meeting was held on Jan. 26, 2023. Despite the identified risk, the CDC continues to recommend booster shots for all people over six months of age.