Scientists in America are investigating a potential link between Pfizer’s new Covid booster and the heightened risk of stroke in people aged 65 and over.
This comes after a possible link was found between the updated dose and a higher risk of "ischemic" in the three to four weeks following vaccination.
Officials from the Centres for Disease Control and Prevention and the US Food and Drug Administration say that despite the link being found, other systems that are used to track vaccine outcomes have not established a similar connection.
