Enlarge / A vial of the updated 2023-2024 formula of Pfizer’s COVID-19 vaccine at a CVS Pharmacy in Eagle Rock, California, on September 14, 2023. (credit: Getty | Irfan Khan)

Staying up to date on COVID-19 vaccines can cut the risk of COVID-related strokes, blood clots, and heart attacks by around 50 percent in people ages 65 years or older and in those with a condition that makes them more vulnerable to those events, according to a new study from the Centers for Disease Control and Prevention.

The finding, published this week in the CDC’s Morbidity and Mortality Weekly Report, should help ease concerns that the shots may conversely increase the risk of those events—collectively called thromboembolic events. In January 2023, the CDC and the Food and Drug Administration jointly reported a preliminary safety signal from their vaccine-monitoring systems that indicated mRNA COVID-19 vaccines may increase the risk of strokes in the 21 days after vaccination of people ages 65 and older. Since that initial report, that signal decreased, becoming statistically insignificant. Other vaccine monitoring systems, including international systems, have not picked up such a signal. Further studies (summarized here) have not produced clear or consistent data pointing to a link to strokes.

In May, the FDA concluded that the evidence does not support any safety concern and reported that “scientists believe factors other than vaccination might have contributed to the initial finding.”