Los Angeles, Jan 14 (IANS): The US Centers for Disease Control and Prevention (CDC) and the US Food and Drug Administration (FDA) have announced that their surveillance system flagged a possible link between the new Pfizer-BioNTech bivalent Covid-19 vaccine and strokes in people aged 65 and older.

Following the availability and use of the updated vaccine, CDC's Vaccine Safety Datalink, a near real-time surveillance system, met the statistical criteria to prompt additional investigation into "whether there was a safety concern" for ischemic stroke in people aged 65 and older who received the updated vaccine, Xinhua news agency reported, citing a statement on the CDC website.

The investigation "raised a question of whether" stroke risk was elevated in the 21-day period post-vaccination versus 22 to 44 days post-vaccination, according to the CDC.

A preliminary study using the US Veterans Affairs database did not indicate an increased risk of ischemic stroke following the updated vaccine, according to the CDC.

The Vaccine Adverse Event Reporting System managed by CDC and FDA has not seen an increase in reporting of ischemic strokes following the vaccine.

Pfizer and BioNTech said in a statement that "there is no evidence to conclude that ischemic stroke is associated with the use of the companies' Covid-19 vaccines."