U.S. FDA, CDC see early signal of possible Pfizer bivalent COVID shot link to strokeJan 13 (Reuters) - (This Jan. 13 story has been refiled with an edited headline to clarify that the link to a stroke is possible, not definite.)The U.S. Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) said on Friday that a CDC vaccine database had uncovered a possible safety issue in which people 65 and older were more likely to have an ischemic stroke 21 days after receiving the Pfizer/BioNTech bivalent shot, compared with days 22-44."Although the totality of the data currently suggests that it is very unlikely that the signal in VSD (Vaccine Safety Datalink) represents a true clinical risk, we believe it is important to share this information with the public," the health authorities said.Pfizer and BioNTech said in a statement that they have been made aware of limited reports of ischemic strokes in people 65 and older following vaccination with their updated shot."Neither Pfizer and BioNTech nor the CDC or FDA have observed similar findings across numerous other monitoring systems in the U.S. and globally and there is no evidence to conclude that ischemic stroke is associated with the use of the companies' COVID-19 vaccines," the companies added."