The Centers for Disease Control and Prevention is investigating a possible “safety concern” recently detected in some COVID-19 vaccines.
The CDC announced on Friday that it’s investigating the possibility for enhanced risk of ischemic stroke, the most common type, in people older than 65 who received the bivalent Pfizer-BioNTech vaccine for COVID-19.
Bivalent COVID-19 vaccines, sometimes referred to as “updated” vaccines, were first authorized last fall. They were designed to target both the original COVID-19 strain and two subvariants of the Omicron strain.
The same “preliminary signal” of stroke risk was not detected in the bivalent Moderna vaccine, according to the CDC.
However, the agency cautioned that the stroke risk detected by one system was not found by other systems, and has been contradicted by studies and data. The agency said it would keep an eye on the situation but recommended no change in how vaccines are currently given.
Officials told the Washington Post that they debated whether to disclose the finding, because it’s considered to be unreliable. But a CDC official said agencies hope that publicizing it anyway “will build confidence.”
Pfizer spokesman Kit Longley told the Post that the company and BioNTech, its German partner, are aware of “limited reports” of stroke. But “there is no evidence to conclude that ischemic stroke is associated with the use of the companies’ covid-19 vaccines,” Longley said.
The findings will be discussed at a Jan. 26 meeting of the Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee, according to the announcement.
Eighty-seven percent of strokes are of the ischemic type, occurring after a vessel supplying blood to the brain is obstructed, according to Stroke.org.
From Aug. 31 to Oct. 23, there were 12 reports of either ischemic strokes or “transient ischemic attacks” in people who took the bivalent Pfizer-BioNTech vaccine, according to CDC data.
This was a breaking news story. The details were periodically updated as more information became available.