The Claim:
One Twitter gentleman claims that receiving more than one brand of COVID vaccines over time caused an aneurysm in one young adult.
The Facts:
A study published in The New England Journal of Medicine looked at whether giving an additional booster dose of COVID-19 vaccine was safe and effective for adults who had already received a full vaccination series with any of the three COVID-19 vaccines that were granted Emergency Use Authorization (EUA) or approved by the U.S. Food and Drug Administration (FDA). The study found that giving a booster dose of any of these vaccines was safe and triggered an immune response.
The results from this study led to recommendations from the FDA and the Centers for Disease Control and Prevention (CDC) to allow mix-and-match booster vaccinations in the United States. This means that people could get a different booster vaccine than the one they originally received.
There is no evidence that the COVID vaccine causes brain aneurysms, much less enough that it could be deemed common. Each year approximately half a million deaths from brain aneurysms occur worldwide, about half of them in people under 50.