No increased stroke risk linked to Pfizer's Covid boosters, federal officials say

A reported spike in monitoring data was a mirage, officials said.

Concerns that Covid booster shots made by Pfizer-BioNTech may increase the risk of stroke in people age 65 and older have not been confirmed by intensive scientific investigation, federal officials said Friday. /p>

"It is highly unlikely" that the risk is real, officials said. They urged Americans 6 months and older to continue getting booster shots. Federal officials decided to release the concern and the results of their investigation despite concerns that the revelation could stoke anti-vaccine sentiment.

"We believe that it is important to share this information with the public,” said a joint statement from the Centers for Disease Control and Prevention and the Food and Drug Administration.

Officials have declined requests to discuss details of their investigation.< /p>

The bivalent vaccine is designed to thwart the original version of the coronavirus as well as versions of the Omicron variant that were circulating in the states Bivalent vaccines made by Pfizer-BioNTech and Moderna are currently the only boosters available in the United States, and scientists are engaged in a heated debate over their usefulness compared to the original vaccines.

It is unclear whether the new insurance will encourage Americans to receive a bivalent vaccine if they have not already done so. So far, only 39% of adults aged 65 and over and only 16% of those aged 5 and over have received a bivalent booster injection.

Concerns about a possible link to ischemic strokes – which can cut off the blood supply to the brain – first emerged late last year. Data from the Vaccine Safety Datalink, a federal safety monitoring system, suggested that Americans ages 65 and older may be at increased risk of ischemic stroke within 21 days of receiving a Pfizer bivalent injection. -BioNTech.

This signal was specific to the bivalent vaccine manufactured by Pfizer-BioNTech. No similar concerns were related to the original Covid vaccines or Moderna's bivalent boosters.

The data prompted federal officials to scour other databases on the vaccine safety, as well as comments from the United States and other countries. Investigators found no evidence of an increased risk of stroke from any of these sources, federal officials said in their statement.

Officials Feds plan to discuss the results Jan. 1. 26 at a meeting of scientific advisors to the F.D.A. on future Covid vaccines.

The Vaccine Safety Datalink is a real-time surveillance system, a collaboration between the C.D.C. and integrated healthcare organizations and networks across the United States. The system uses electronic health data from a dozen sites nationwide to monitor vaccine safety.

Among approximately 550,000 people aged 65 and over who received the bivalent Pfizer-BioNTech booster, 130 had ischemic strokes within 21 days of injection, raising concerns that the two events were related. But analyzing the data using a different method did not reveal an increased risk of ischemic stroke.

Another database, the Vaccine Adverse Event Reporting System, operated by the C.D.C. and the F.D.A., also did not detect an ischemic stroke signal. Neither a large study of bivalent vaccines using data from the Centers for Medicare and Medicaid Services, a preliminary study using the Veterans Affairs Database, nor the Pfizer-BioNTech Global Safety Database.

< p class="css-at9mc1 evys1bk0">Other countries have not observed an increased risk of ischemic stroke with bi...