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Dr Gérald Kierzek (Medical Director of Doctissimo)
Millions of people around the world have received two vaccines – against influenza and Covid – simultaneously. Following a survey conducted by the American monitoring system Vaccine Safety Datalink, this practice could increase the risk of stroke. A thorough investigation must be carried out by the American administration to decide whether or not to change current practices.
In the United States as in France, the recommendations concerning vaccination against influenza and Covid-19 are clear: it is quite possible to perform the two injections on the same day. Millions of Americans and French people have followed these recommendations.
An increased risk of stroke following vaccines?
Last November, a small real-time government surveillance system that monitors side effects – including pathologies – caused by vaccines, known as Vaccine Safety Datalink (VSD), detected a possible link between the Covid vaccine and strokes in people over 65.
Investigators found that 130 elderly people suffered strokes within 21 days of the Pfizer vaccine booster shot among approximately 550,000 recipients in the VSD database. A man in his 60s died a month after the stroke, which was determined to be the probable cause of his death. However, the overall increase in strokes appears to be diminishing over time, weakening the link to the Covid vaccine.
First reassuring elements
Food and drug administration (FDA) officials investigating the link said most patients also received their flu shot on the same day, which could be one explanation.
The organization simultaneously looked at data from 4.25 million older people who received Pfizer’s omicron booster and found no increased risk of stroke. The agency’s review of the Vaccine Adverse Event Reporting System (VAERS) database also found no increased risk. Finally, the FDA also contacted international health agencies and Pfizer to find out what they observed in their data, and the link to stroke was not substantiated.
Further FDA investigation
According to Richard Forshee, deputy director of the FDA’s office of biostatistics, told the agency’s Independent Vaccine Committee: “So far, the data we’ve seen suggests no safety risk from bivalent boosters from age 65 onwards.”
However, FDA reviewers performed another small analysis indicating that older adults who received both the Pfizer omicron booster and a high-dose or adjuvanted flu vaccine on the same day may have a higher risk of ‘stroke. The FDA is therefore launching a larger study to examine potential safety issues resulting from simultaneous vaccination against Covid and influenza.
Whether or not to pursue this recommendation
The objective of this investigation for the FDA is to determine more precisely whether this recommendation should be pursued next year. His results will help him decide.
For now, health officials are still recommending people get both vaccines at once, because being infected with the flu or Covid also increases the risk of stroke. For Dr Gérald Kierzek, emergency doctor and medical director of Doctissimo, “there is a whole vaccination surveillance system, so for now there is no need to worry, we just have to monitor this trend”.