COVID, Flu Shot Given Together Linked to Stroke Risk

A new study warns that getting the vaccine for COVID-19 at the same time as the flu shot may increase the risk of strokes caused by blood clots in the brains of seniors. The dangerous side effect appears to occur when both jabs are given simultaneously to those over the age of 85.

According to CNN, experts at the Food and Drug Administration (FDA) noticed the red flag when analyzing data from Medicare claims. The new study follows on the heels of a previous report issued by the Centers for Disease Control and Prevention (CDC) along with the FDA last January that said one of their vaccine safety monitoring studies, the Vaccine Safety Datalink, had noticed a possible risk of stroke after older adults received a dose of Pfizer’s bivalent COVID-19 vaccine and a high-dose or adjuvanted flu shot on the same day. This triggered closer surveillance of the stroke risk by the agencies when both shots were given to seniors.

While the risk is small ─ about 3 strokes or transient ischemic attacks for every 100,000 doses given ─ the FDA study revealed that the serious side effect appeared to be triggered by the high-dose or adjuvanted flu shot that boosts the immune system to mount a stronger response to the shot.

Further analysis of Medicare data found that there was a slight increased risk among seniors 65 years and older who received only the flu shot. That extra risk was associated with 1-2 strokes for every 100,000 doses, says CNN.

“The absolute risk is miniscule,” noted Dr. Steve Nissen, a cardiologist and researcher at the Cleveland Clinic in Ohio. “I mean it is trivial in comparison to the risk for people over 85 dying from COVID.”

In the meantime, the CDC is following up on the data with other studies to further investigate the link.

“Available data do not provide clear and consistent evidence of a safety problem for ischemic stroke with bivalent mRNA COVID-19 vaccines when given along or given simultaneously with influenza vaccines, or when influenza vaccine is given alone,” said Dr. Tom Shimabukuro, director of the Immunization Safety Office at the CDC.

Experts suggest that while researchers probe deeper into the potential association between vaccines and increased risk of stroke, everyone should still get their vaccines, especially older persons who are at increased risk of serious outcomes from either the flu or COVID-19 infections.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University, suggested that if seniors are concerned, they should spread out their shots.

“If you want to minimize the chance of interactions and minimize confusing the side effects from one with another, you wait about two weeks between the vaccines,” advised Dr. Peter Marks, the director of the Center for Biologics Evaluation and Research at the FDA.

The FDA investigators found no increase in stroke risk for people over age 65 who received either the Pfizer or Moderna COVID-19 vaccine. They did find a slight increased risk of stroke for those aged 85 years and older who got the Pfizer shot, but not the Moderna version of the bivalent vaccine.

Seniors aged 65 and older, however, who got one of the COVID bivalent vaccines along with the high-dose influenza shot, also had an increased risk of blood clot in their brains, says CNN. The study is available as a preprint and has not been peer reviewed.