CDC investigating possible safety signal for Pfizer bivalent booster
Lisa Balleaux
On January 13, the U.S. Centers for Disease Control and Prevention announced they will be investigating a preliminary safety signal for one of the COVID-19 bivalent booster vaccines.
This safety signal was detected by only one of many safety systems; other safety systems, databases, and countries are not seeing the same link, nor has it been seen in other brands of COVID-19 vaccine.
The signal is unlikely to represent a true clinical risk. Please continue vaccinating patients with the bivalent COVID-19 vaccine when they are due.
Here is more detailed information:
Picking up the signal
- CDC’s Vaccine Safety Datalink (VSD), one of several vaccine safety monitoring systems in place in the United States, has picked up a signal indicating a potential risk of ischemic stroke in adults over 65 who received the Pfizer-BioNTech COVID-19 bivalent booster.
- There is no signal for the Moderna COVID-19 bivalent booster.
- U.S. government agencies use multiple, complementary safety monitoring systems to help detect possible vaccine statistical signals as early as possible and to know when or if to investigate a possible issue. VSD, the system that picked up this signal, is one of these.
- As a response to this signal in the VSD, the CDC worked with the U.S. Food and Drug Administration to further investigate this potential side effect in other safety monitoring systems (such as VAERS) and clinical databases (including those for Medicare, the VA, Israel, and some European countries). No clinical risk of ischemic stroke has been identified in other sources.
- Other countries have not observed an increased risk for ischemic stroke with bivalent vaccines.
- Pfizer-BioNTech’s global safety database also does not indicate a signal for ischemic stroke with this vaccine.
What does this mean for clinicians?
- Overall, the totality of the data suggests it is very unlikely that the signal in VSD represents a true clinical risk. In the spirit of transparency, CDC wanted to share this early information with the public.
- No change in vaccination practice is recommended. CDC continues to recommend that everyone ages 6 months of age and older stay up to date with COVID-19 vaccination; this includes individuals who are currently eligible to receive an updated (bivalent) vaccine.
- Public health supports the continued assessment of vaccine safety. The finding from the Vaccine Safety Datalink shows that the system is working, and we are being vigilant in detecting any adverse health outcomes associated with the COVID-19 vaccine.
What’s next?
CDC and FDA will continue to evaluate additional data from the VSD and other vaccine safety systems. These data and additional analyses will be discussed at the upcoming January 26 meeting of the FDA’s Vaccines and Related Biological Products Advisory Committee.
We will update you when more information becomes available.
In partnership,
COVID-19 Vaccine Program
Prevention and Community Health Division
Washington State Department of Health
COVID.vaccine@doh.wa.gov
360-236-3873 | www.doh.wa.gov |