The Centers for Disease Control and Prevention last week said it found an increased risk of ischemic stroke in people age 65 and older who received Pfizer’s COVID-19 bivalent booster — but the agency omitted key information needed in order to accurately assess the risk versus benefit of getting the vaccine.
The Centers for Disease Control and Prevention (CDC) on Jan. 13 published this statement on its website: “CDC & FDA Identify Preliminary COVID-19 Vaccine Safety Signal for Persons Aged 65 Years and Older.”
The signal was identified through Vaccine Safety Datalink (VSD), “a collaborative project between CDC’s Immunization Safety Office, integrated health care organizations, and networks across the U.S.,” that “uses electronic health data from participating sites to monitor and assess the safety of vaccines.”
The CDC and U.S. Food and Drug Administration analysis of VSD data found:
- There was an increased risk of ischemic stroke in bivalent booster recipients ages 65 and older.
- The risk was present in the Pfizer formulation but not in Moderna’s.
- The signal was raised because of increased stroke risk in the 21 days following inoculation compared to the risk on days 22-42.
- The signal did not change the CDC’s recommendations for either bivalent boosters (Pfizer or Moderna).
Let’s break this down …
VSD raw data is not readily available to the public, so key questions remain around the significance of the signal and the criteria being used to prompt further investigation.
The CDC bulletin indicates that the risk of stroke is higher immediately after getting a Pfizer bivalent booster. But how much higher? The CDC doesn’t tell us.
Moreover, the CDC’s concern is around the increased stroke risk in the first three weeks compared to the risk in the second three weeks. But what is the absolute risk? In other words, how does the risk of stroke in boosted individuals compare to those who are not boosted?
The CDC does not tell us that, either….