CDC, FDA to Investigate Weak Signal for Stroke in Seniors with Pfizer Bivalent Vaccine

COVID-19; Research and Data

​​The CDC and FDA issued preliminary findings about monitoring the bivalent COVID-19​ vaccine’s safety that​ discusses an initial increase of strokes in their safety monitoring data for the Pfizer bivalent COVID-19 vaccine. As part of routine surveillance, the CDC detected a preliminary signal for stroke in people ages 65 and older who received the Pfizer-BioNTech COVID-19 bivalent mRNA vaccine. However, this statistical signal is lower than the signals seen for other issues related to the vaccines. As a response to the signal, the CDC and FDA examined several large databases including:  

  • ​Medicare’s database of 5 million doses 
  • The Veterans’ Affairs’ database of millions of veterans​  
  • Israel’s database 
  • Various European countries’ databases  

To date, the aforementioned organizations have not seen an association or increased risk in stroke from vaccines in these databases. The totality of the data currently suggests that it is very unlikely that the initial signal represents a true clinical risk. 

However, for the sake of transparency, the FDA and CDC are issuing a statement about the signal and the results of their investigation so far. Putting this preliminary data in context, we know that the bivalent vaccine significantly lowers the risk of develop serious symptoms, being hospitalized or dying from COVID-19 compared to those who have either already been infected or been vaccinated but without a booster. The COVID-19 virus causes more complications and death among individuals over the age of 65, particularly those with health conditions. 
This announcement does not change AHCA/NCAL’s recommendation for residents to be vaccinated. Should a person have concerns, they may also request the Moderna bivalent vaccine which did not have an increased signal for strokes.