According to the US Centers for Disease Control and Prevention (CDC) and Food and Drug Administration (FDA) surveillance system, the new Pfizer-BioNTech bivalent COVID-19 vaccine can be associated with strokes in people who are 65 and older. As per the statement on the CDC website, statistical criteria matched the reports of further investigation on "whether there was a safety concern" for ischemic stroke in people 65 and older who received the updated vaccine following the availability and use of the updated vaccine.

The analysis "raised a doubt" about whether stroke risk was increased in the first 21 days after immunisation compared to 22 to 44 days post-vaccination. Preliminary research utilising the US Veterans Affairs database revealed that the revised vaccination did not appear to raise the incidence of ischemic stroke. The Vaccine Adverse Event Reporting System managed by the CDC and FDA has not seen an increase in the reporting of ischemic strokes following the vaccine.

Additionally, Pfizer and BioNTech stated in a statement that there is no evidence to indicate that use of the companies′ COVID-19 vaccines is connected with ischemic stroke. 

(Source: https://health.economictimes.indiatimes.com/news/industry/us-fda-cdc-see-early-signal-of-pfizer-bivalent-covid-shots-link-to-stroke/96982599 )