No Evidence of Greater Stroke Risk with Bivalent COVID-19 Vaccines

In January 2023, 5 months after the U.S. FDA authorized two bivalent COVID-19 vaccines (Pfizer-BioNTech and Moderna), postmarketing surveillance data suggested excess risk for stroke following administration of the Pfizer-BioNTech vaccine, as well as elevated risk with concomitant administration of high-dose or adjuvanted influenza vaccine. Now, investigators have conducted a self-controlled study of 5 million Medicare beneficiaries (median age, 74) who received either of the bivalent COVID-19 vaccines, a high-dose or adjuvanted flu vaccine, or concomitant COVID-19 and flu vaccines. Neurovascular events (i.e., hemorrhagic or nonhemorrhagic stroke or transient ischemic attack) were attributed to the vaccine if they occurred in two early time…