The flu vaccine has been found to increase the risk of stroke among elderly individuals who also received the bivalent COVID-19 booster, according to a study published in the Journal of the American Medical Association (JAMA). The study, funded by the U.S. Food and Drug Administration (FDA), was conducted after the agency detected a safety signal among older people who received the boosters. The researchers analyzed data from Medicare recipients and found that over 11,000 individuals had strokes within 90 days of receiving the vaccine.
Cardiologist Dr. Peter McCullough expressed concern over the high number of strokes following influenza/COVID-19 vaccination in Medicare recipients. He called for a halt on the administration of both vaccines until large-scale randomized trials can be conducted in selected populations at risk for hospitalization or death.
The study compared the risk of stroke within different time periods following vaccination and found an elevated risk of stroke among those who received the Pfizer booster and those who received the Moderna booster in the first 42 days. When analyzing the data of individuals who had taken both the bivalent booster and a flu vaccine, they found that the elevated risk of stroke persisted only among those who had taken both vaccines at the same time. They also found an elevated risk of stroke among those who took only the flu shot.
While the study did not include an unvaccinated control group, it highlighted a small association between stroke and the flu vaccine. The researchers suggested that the observed association between vaccination and stroke in the concomitant subgroup was likely driven by a high-dose or adjuvanted influenza vaccination. Adjuvanted flu vaccines are typically offered to individuals under 65, while high-dose flu vaccines are given to people over 65.
Critics argue that the study is a “nothing-burger” designed to divert attention from the potential dangers of the COVID-19 vaccine. Brian Hooker, Ph.D., chief scientific officer for Children's Health Defense, stated that the study fails to address the thrombotic nature of the COVID-19 vaccine and its link to clotting and heart disorders. He criticized the focus on this study while neglecting other studies that provide more comprehensive answers.
Despite the safety signal identified by the CDC regarding the increased risk of ischemic stroke in older individuals who received the bivalent booster, both the CDC and FDA continued to recommend concomitant administration of the flu vaccine and the COVID-19 booster. The agencies acknowledged the need for further research into the issue.
The JAMA study is not the first to find an increased risk of stroke associated with the flu vaccine in older adults. However, public health recommendations suggest administering multiple vaccines at once to increase vaccine uptake. Researchers emphasize the importance of evaluating tolerability and safety in specific populations, such as frail older adults, before making these recommendations.
While the study provides reassurance about the COVID-19 boosters not being related to an increased risk of stroke, more studies are needed to understand the association between high-dose or adjuvanted influenza vaccination and stroke. French and Israeli researchers also found no safety signals for stroke following COVID-19 vaccination.
