Investigation of an early signal for stroke associated with COVID-19 bivalent vaccines turned into suspicion of high-dose or adjuvanted flu shots instead, based on a large U.S. population-based study.
When researchers inspected a large Medicare database, they found no evidence of a significantly elevated risk for stroke at 1-21 days or 22-42 days after vaccination with either of the mRNA COVID vaccines distributed for the 2022-2023 respiratory season when compared with the 43-90 day control window, reported researchers led by Yun Lu, PhD, a statistician of the FDA in Silver Spring, Maryland. There was a significant excess of nonhemorrhagic stroke for people with concomitant administration of Pfizer-BioNTech’s bivalent vaccine plus a high-dose or adjuvanted influenza vaccine during the 22-42 days risk window (risk difference of 3.13 out of 100,000 doses); and a significant excess of transient ischemic attack for people with concomitant administration of Moderna’s bivalent COVID vaccine plus a high-dose or adjuvanted influenza vaccine during the 1-21 days risk window (risk difference of 3.33 out of 100,000 doses). Read the paper in JAMA