The US Food and Drug Administration and the US Centers for Disease Control analyzed data from a vaccine safety monitoring study called the Vaccine Safety Datalink. They identified a small and uncertain risk of stroke for older people who received both a dose of Pfizer’s bivalent Covid-19 vaccine and a high-dose or adjuvanted flu shot on the same day. Specifically, the risk was roughly 3 strokes or transient ischemic attacks (reversible strokes) for every 100,000 doses given.
Five additional follow up studies designed to sort out the details of this issue have not found any additional risk of stroke after vaccination for Covid-19, influenza or both. No study has shown a direct cause-and-effect relationship. Remember, there is a big difference between association (2 things happen at the same time) and causation (one thing directly made something else happen). There is a strong association between wearing socks and being killed in a car wreck. Many, many people died with their socks on. We can agree there is zero causation between wearing socks and motor vehicle fatalities.
So what does this all mean? Does 1 – 3 strokes per 100,000 doses represent a big or small risk? Let’s put this into perspective.
· The Insurance Institute for Highway Safety reports a national average of 13 deaths per 100,000 people.
· The national fatality rate for people 65 and older from influenza is 22 deaths per 100,000 people.
· In Colorado, the death rate from Covid is 246 deaths per 100,000 people.
The odds are greatly in your favor if you get the Covid and influenza vaccines. Experts suggest spreading out the 2 vaccines by several weeks may lower the risk even further.
If you would like to dig deeper into the details, take a look at this summary from the Advisory Committee on Immunization Practices (ACIP) October 25, 2023 meeting.