Real-time surveillance flagged a possible safety concern with the Pfizer-BioNTech COVID-19 Bivalent Vaccine.
On January 13, the FDA and the CDC announced a possible safety signal emerged for the Pfizer-BioNTech COVID booster from the CDC’s Vaccine Safety Datalink (VSD)—a real-time vaccine surveillance system. The signal identified statistical data concerning whether people 65 years or older were more likely to experience an ischemic stroke in the 21 days following vaccination compared with days 22 through 42 after receiving the booster.
Ischemic stroke occurs when blood flow to the brain gets partially or completely blocked by a blood clot or other obstruction.
According to the announcement, U.S. government agencies use multiple safety monitoring systems to detect possible safety signals for vaccines. Often these systems observe signals that could be due to factors other than the vaccine itself. The agencies did not identify a safety signal for Moderna’s COVID-19 Bivalent booster.
The agencies say they will continue to evaluate additional data from their monitoring systems and will present their analyses at the FDA’s Annual Vaccines and Related Biological Products Advisory Committee meeting on Thursday, January 26.
The CDC and FDA suggest it’s unlikely the VSD signal indicates a genuine risk. Therefore, they recommend no change in COVID vaccination practice at this time.
After bivalent booster vaccination, the Vaccine Adverse Event Reporting System (VAERS) received 5,542 reports of adverse events among people 12 years old or older. Of those, 95.5% were non-serious, and 4.5% were serious events. Serious events included five cases of myocarditis, four accounts of pericarditis, and 20 reports of COVID-19 disease.
VAERS data also indicates that in 2022, there were 37 reports of ischemic stroke in adults 65–79 years and 24 in people 80 years and older after receiving Pfizer-BioNTech’s COVID vaccine. Though, the data does not detail whether the vaccines received were the bivalent booster shot or the primary series.
However, a CNN report claims that out of 550,000 older adults who received the booster, VSD tracking showed 130 experienced strokes within three weeks after vaccination.