Advisory Panel Meets Today to Discuss Rare Blood Clots in Patients Given J&J Vaccine

An expert panel of the Centers for Disease Control and Prevention (CDC) is meeting today to review blood-clot incidents reported in a handful of patients who received Johnson & Johnson’s (J&J) one-dose COVID-19 vaccine.

The advisory panel will assess if there’s a potential link to the J&J vaccine and vote on whether an update to the shot’s instructions for use is warranted.

The FDA, which is also investigating the adverse events, will follow up with its own review of the expert panel’s analysis. In the meantime, the agencies have recommended that states temporarily stop using the vaccine “out of an abundance of caution.”

“This [pause] is important, in part, to ensure that the healthcare provider community is aware of the potential for these adverse events and can plan for proper recognition and management due to the unique treatment required with this type of blood clot,” said Center for Biologics Evaluation and Research (CBER) Director Peter Marks.

Marks provided specifics on Tuesday, stating that the FDA and CDC are currently reviewing six U.S. cases of a rare and severe type of blood clot, cerebral venous sinus thrombosis (CVST), reported only in women age 18 to 48 years who had been given J&J’s one-dose vaccine. The patients saw symptoms six to 13 days after vaccination as well as low levels of blood platelets, he said, noting that the specific type of blood clot they experienced requires a different type of treatment than might normally be given.

“Usually, an anticoagulant drug called heparin is used to treat blood clots,” he said. “In this setting, administration of heparin may be dangerous, and alternative treatments need to be given.”

The CBER chief offered some reassurance, saying the adverse events “appear to be extremely rare” and noting that more than 6.8 million J&J shots were administered in the U.S. as of Monday.

Although the pause’s timeframe will be shaped by what is learned in the agencies’ investigations, Acting FDA Commissioner Janet Woodcock said that the FDA expects it to last “a matter of days.”

J&J, acknowledging the adverse events, said that it is delaying the rollout of its vaccine in Europe as a precaution.

Previously, a small number of blood-clot incidents were reported in patients who received the AstraZeneca (AZ) COVID-19 vaccine, prompting halts in vaccinations in Europe as the European Medicines Agency investigated. The agency concluded that the AZ vaccine should include the risk of very rare blood clots on its list of possible side effects.

Because the blood clots were reported in younger adults, many EU countries have introduced age restrictions for the AZ shot, limiting the inoculations to older individuals. In the UK, for example, an advisory committee to the Medicines and Healthcare products Regulatory Agency said a different vaccine should preferably be administered to individuals under age 30 (DID, April 8).

Like the J&J shot, AZ’s two-dose inoculation is an adenoviral vector-based vaccine. — James Miessler