Updated 8:24 AM EDT, Thu October 26, 2023
Vaccines for Covid-19 and influenza may slightly increase the risk of strokes caused by blood clots in the brains of seniors, particularly when the two vaccines are given at the same time and when they are given to adults who are age 85 and older, according to a new study.
The safety signal was detected by experts at the US Food and Drug Administration who analyzed data from Medicare claims.
It is the second study to find an elevated risk of stroke for seniors after Covid-19 and flu vaccinations given together. The US Centers for Disease Control and FDA issued a public communication in January explaining that one of their near real-time vaccine safety monitoring studies — called the Vaccine Safety Datalink — had picked up a small and uncertain risk of stroke for older adults who received a dose of Pfizer’s bivalent Covid-19 vaccine and a high-dose or adjuvanted flu shot on the same day. That study triggered the FDA’s broader look at strokes after vaccination noted in the medical records of seniors on Medicare.