Infectious Disease

Safety signal for COVID-19 booster unlikely to be ‘true clinical risk,’ officials say

January 17, 2023

2 min read

ADD TOPIC TO EMAIL ALERTS

Receive an email when new articles are posted on

Please provide your email address to receive an email when new articles are posted on . ” data-action=subscribe> Subscribe

We were unable to process your request. Please try again later. If you continue to have this issue please contact [email protected].

Back to Healio

Health officials said a safety signal detected by a national surveillance system is “very unlikely” to represent a “true clinical risk” for stroke among older people who received the Pfizer-BioNTech bivalent COVID-19 booster.

The CDC and FDA said they came to that conclusion after multiple analyzes of other vaccine surveillance databases failed to validate the signal from the CDC’s Vaccine Safety Datalink (VSD), a near real-time surveillance system.

IDN0123PfizerSignal_Graphic_01_WEB

Information from the VSD met the statistical criteria to trigger an investigation into whether people aged 65 years or older were more likely to experience ischemic stroke within 21 days of receiving the updated booster compared with 22 to 42 days after vaccination.

“Often these safety systems detect signals that could be due to factors other than the vaccine itself,” the CDC and FDA said in a statement. “All signals require further investigation and confirmation from formal epidemiologic studies. When one system detects a signal, the other safety monitoring systems are checked to validate whether the signal represents an actual concern with the vaccine or if it can be determined to be of no clinical relevance.”

Analyzes of five other safety databases — including the Vaccine Adverse Event Reporting System managed by the CDC and FDA, and databases kept by CMS and the US Department of Veterans Affairs — did not show any increase in reporting of ischemic stroke related to bivalent COVID-19 booster vaccines.

“No change in vaccination practice is recommended,” the CDC and FDA said. The CDC still recommends that eligible people aged 6 months or older stay up to date on vaccinations and boosters, which have been shown to reduce the risk for severe disease from COVID-19.

“There is no evidence to conclude that ischemic stroke is associated with [Pfizer-BioNTech’s] COVID-19 vaccines,” Pfizer told Healio in a statement. “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 vaccination with the omicron BA.4/BA.5-adapted bivalent vaccine.”

The CDC and FDA said they will continue to evaluate data from the safety systems, with the most recent data and analyzes expected to be discussed by the FDA’s Vaccines and Related Biological Products Advisory Committee at its Jan. 26 meeting.

“Although the totality of the data currently suggests that it is very unlikely that the signal VSD represents a true clinical risk, we believe it is important to share this information with the public,” the CDC said.

References:

perspective

back to top
Amesh A. Adalja, MD, FACP, FACEP, FIDSA)

Amesh A. Adalja, MD, FACP, FACEP, FIDSA

A signal should not be confused with a causal relationship. The relationship of the Pfizer bivalent SARS-CoV-2 booster vaccine and ischemic stroke seen in one vaccine safety database appears to be coincidental and not validated by looking at multiple other sources of data.

Although this was an example of the system working well by flagging and running down a signal very rapidly, unfortunately it will not stop the anti-vaccine forces from using it to erode confidence in the vaccine.

Amesh A. Adalja, MD, FACP, FACEP, FIDSA

Senior scholar

Johns Hopkins Center for Health Security

Disclosures: Adalja reports being on a speaker’s bureau for Pfizer.

ADD TOPIC TO EMAIL ALERTS

Receive an email when new articles are posted on

Please provide your email address to receive an email when new articles are posted on . ” data-action=subscribe> Subscribe

We were unable to process your request. Please try again later. If you continue to have this issue please contact [email protected].

Back to Healio

COVID-19 virus graphic thin banner

COVID-19 Resource Center

Related Articles