Stroke after Pfizer’s updated booster shots

In early January 2023, it become known that the CDC's near real-time surveillance system (the Vaccine Safety Datalink containing health records of more than 12 million Americans) detected a possible increase in ischemic stroke in people 65 and older who recently got one of Pfizer’s (BioNTech) updated booster shots. It found that 130 seniors had the stroke within 21 days of the shot (compared with days 22-44 following vaccination). This 'met the statistical criteria to prompt additional investigation', the CDC statement said. CDC officials used an alternative methodology to conduct a different analysis in the VSD database but could not replicate the finding. They also checked the Center for Medicare and Medicaid Services system, containing 83.9 million individuals, and the Veterans Affairs database, with nine million people. Neither dataset indicated an increased risk of ischemic stroke following a bivalent vaccine. A large study of updated (bivalent) vaccines (from Pfizer-BioNTech and Moderna) using the Centers for Medicare and Medicaid Services database revealed no increased risk of ischemic stroke. The Vaccine Adverse Event Reporting System (VAERS) managed by CDC and FDA and the Canadian safety reports have not seen an increase in reporting of ischemic strokes following the updated (bivalent) vaccine. 

Pfizer-BioNTech’s global safety database has not indicated a signal for ischemic stroke with the updated (bivalent) vaccine. Other countries have not observed an increased risk for ischemic stroke with updated (bivalent) vaccines.

A spokesperson for Pfizer said that "compared to published incidence rates of ischemic stroke in this older population, the companies to date have observed a lower number of reported ischemic strokes following the vaccination with the Omicron BA.4/BA.5-adapted bivalent vaccine... This is not proof... <but> there may be a link here".

More than half a million of seniors received the updated booster shot.

Here are a few examples of VAERS reports:

67-year-old female received Pfizer bivalent vaccine (her 4th dose of COVID-19 vaccines). 11 days later she was diagnosed with ischemic right lacunar stroke after experiencing weakness of left area, hand and leg. Right lacunar ischemic blockage was confirmed by brain confirmed by MRI.

69-year-old male had regular reactions of light fever, pain on the site of injection, general discomfort and nothing else with symptoms going away within 24 hours, after all 5 doses of his CVID-19 vaccines. Then on the 4th day after his bivalent booster (5th dose) he started vomiting, lost balance and experienced dizziness. He was about to be discharged with the diagnosis of vertigo and his husband noticed that he was having generalized body cramps and told the doctor he was manifesting stroke like symptoms. He was then taken for an MRI and the stroke was on the low left cerebellar side, which was diagnosed as ischemic stroke. The patient did not have a history of stroke prior to the vaccine. All testing to see what may have caused the stroke were negative. He had a loop monitor inserted into his chest and that was also negative. He was then admitted and stayed for 2 days. He was doing excellent until 2-weeks after the booster dose when he experienced the same symptoms and was diagnosed with another stroke.

71-year-old male was taken to emergency because of dizziness and feeling unwell, 3 days after Pfizer bivalent booster (his 5th dose of COVID-19 vaccines). His systolic blood pressure was in the 230s. He had left side weakness with facial droop and arm drift. Patient was diagnosed with acute ischemic stroke. 

71-year-old female was taken by ambulance from home to hospital, days after her 5th, bivalent dose of Pfizer/BioNTech vaccine. Husband reports symptoms to be slurred speech, overall weakness in body, thrashing around in bed. Admitted to hospital with diagnosis of ischemic stroke. 

1.5 hours after receiving bivalent Moderna vaccine (his 5th COVID-19 vaccine dose), 79-year-old male experienced facial droop, slurred speech and left arm weakness. Patient was diagnosed with acute ischemic stroke.


CDC and FDA Identify Preliminary COVID-19 Vaccine Safety Signal for Persons Aged 65 Years and Older | FDA

Possible Bivalent Vaccine Link to Strokes in People Over 65 (

CDC's vaccine safety datalink flagged possible brain stroke risk | Latest News | Top News | WION - YouTube


#2462038 from the VAERS Database (

#2475627 from the VAERS Database (

#2536857 from the VAERS Database (

#2548970 from the VAERS Database (

#2548970 from the VAERS Database (


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