By Gary Evans, Medical Writer
A vaccine safety surveillance system has detected a “signal” of a possible higher risk of ischemic stroke following vaccination in those age 65 years and older with the bivalent Pfizer-BioNTech COVID-19 shot, the Centers for Disease Control and Prevention (CDC) reports.1 The CDC is investigating, but no change in vaccine recommendations has been made as this report was filed
One of the most common types of stroke, ischemic stroke occurs when a blood clot blocks or narrows an artery leading to the brain. This usually is linked to a buildup of plaque in the arteries.
The “preliminary signal” has not been identified with the bivalent Moderna COVID-19 vaccine.
CDC’s Vaccine Safety Datalink (VSD) sent the signal based on statistical criteria to prompt additional investigation.
“It is important to note that, to date, no other safety systems have shown a similar signal and multiple subsequent analyses have not validated this signal,” the CDC stated.
According to the CDC:
• The Vaccine Adverse Event Reporting System (VAERS) managed by CDC and Food and Drug Administration (FDA) has not seen an increase in the reporting of ischemic strokes following the bivalent vaccine.
• Pfizer-BioNTech’s global safety database has not indicated a signal for ischemic stroke with the bivalent vaccine.
• Other countries have not observed an increased risk for ischemic stroke with bivalent shots.
“Although the totality of the data currently suggests that it is very unlikely that the signal in VSD represents a true clinical risk, we believe it is important to share this information with the public, as we have in the past, when one of our safety monitoring systems detects a signal,” the CDC stated.
The CDC continues to recommend that everyone 6 months of age and older stay up-to-date with COVID-19 vaccination, including those eligible to receive a bivalent vaccine.
The incident was discussed at a recent meeting of the FDA’s Vaccines and Related Biological Products Advisory Committee.
“Our systems are designed to be sensitive to broadly capture potential safety concerns and to be able to rapidly assess those concerns,” Tom Shimabukuro, deputy director of CDC immunization safety, told the FDA panel. “The thoroughness in which these findings are being assessed demonstrates that the safety system works. And you basically saw that process in action working. I think the public and the medical community should be confident that the government has the systems in place to rapidly detect potential safety problems and assess them. We place a priority on communicating in a timely and transparent manner.”
- Centers for Disease Control and Prevention. CDC & FDA identify preliminary COVID-19 vaccine safety signal for persons aged 65 years and older. Updated Jan. 13, 2023. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/bivalent-boosters.html#:~:text=A%20large%20study%20of%20updated,increased%20risk%20of%20ischemic%20stroke