The Centers for Disease Control and Prevention (CDC) recently noted that when a preliminary covid vaccine “safety signal” was identified it began investigating whether the bivalent booster from Pfizer-BioNTech created an increased risk of stroke in people 65 and older.
In the Friday statement, the CDC said that the preliminary signal hasn’t been identified with the Bivalent Moderna COVID-19 vaccine.”Following the availability and use of the updated (bivalent) COVID-19 vaccines, CDC’s Vaccine Safety Datalink (VSD), a near real-time surveillance system, met the statistical criteria to prompt additional investigation into whether there was a safety concern for ischemic stroke in people ages 65 and older who received the Pfizer-BioNTech COVID-19 Vaccine, Bivalent,” the CDC said.”Rapid-response investigation of the signal in the VSD raised a question of whether people 65 and older who have received the Pfizer-BioNTech COVID-19 Vaccine, Bivalent were more likely to have an ischemic stroke in the 21 days following vaccination compared with days 22-44 following vaccination.”
However, the agency now asserts that a detailed review of the databases failed to confirm the preliminary information. Therefore, federal health officials have concluded the risk is extremely low.
The CDC and FDA described the early signal in a statement updating their websites Friday afternoon. The signal set off a debate among officials about whether and how to release the information. CDC officials argued for releasing it, while some other officials, including at the FDA, were concerned that putting out unconfirmed data would fuel anti-vaccine sentiment and scare older Americans into avoiding the boosters. Ultimately, the agencies decided to release the information in the hopes that transparency “will build confidence,” said a CDC official.The signal was detected in the Vaccine Safety Datalink, a collaboration involving the CDC and about a dozen health-care organizations with electronic health records on 12 million people. As part of routine monitoring for possible adverse events, officials noticed late last year that they were picking up indications of higher-than-expected stroke risk, officials said.Among about 550,000 people 65 and older who had already been vaccinated and received a booster dose of the Pfizer bivalent vaccine, 130 people had strokes in the first three weeks after getting the shot. No deaths have been reported. That finding raised a question because it suggested that people who received the bivalent were more likely to have an ischemic stroke in the 21 days following vaccination compared with Days 22 through 44 following vaccination.
Despite the rapid reversal, new studies show that the bivalent boosters, which were intended to defend people against emerging Omicron variants, don’t appear to provide any better protection than the original shot does.
The new mRNA bivalent boosters produced by Moderna and Pfizer only attack the COVID-19 virus about as well as the companies’ first-wave vaccines, according to a blood testing study led by renowned virologist Dr. David Ho, a professor of microbiology and immunology at Columbia University, in New York City.The bivalent shots also failed to promote higher antibody levels or a better immune response than the original COVID-19 vaccines, according to another study led by Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center, in Boston. Both studies were published online Jan. 11 in the New England Journal of Medicine.
As a reminder the U.S. has purchased 171 million doses of the bivalent booster at a cost of $4.9 billion.
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