CDC Set to Meet A Second Time After Delaying Vote on J&J Blood Clot Concerns

The Centers for Disease Control and Prevention (CDC) will convene a second emergency meeting of its Advisory Committee on Immunization Practices at the end of the week to discuss the use of Johnson & Johnson (J&J)’s COVID-19 vaccine, following a delayed vote at its initial discussion on cases of very rare blood clots seen in vaccinated patients.

The panel will meet Friday at 11 a.m. for a six-hour session, markedly longer than its first meeting on April 14, which ran over its planned three-hour time and did not end up with a vote or any recommendations. The new scheduling means that it’s unlikely administrations of the one-dose vaccine will resume in the U.S. until at least next week.

Although no meeting agenda was available by deadline, it’s expected that the panel will vote on whether to advise resuming use of the vaccine and whether the shot’s recommendations for use should be updated to reflect the risk of very rare blood clots.

AstraZeneca (AZ)’s vaccine, an adenoviral-vector vaccine like J&J’s, also prompted investigations after cases of very rare blood clots were seen in the EU. The European Medicines Agency (EMA) concluded that there was a link and that the vaccine should have its label changed to reflect those risks as possible side effects (DID, April 8).

The FDA recommended last week that jabs of the J&J vaccine be paused in all states after six cases of extremely rare blood clots were reported in female U.S. patients between the ages of 18 and 48, a safety concern both the FDA and CDC are looking into. The agency said it is still working with the CDC on reviewing the vaccine safety data and did not offer insight on when the evaluation may conclude, stating it will offer updates “as they become available.”

During its initial meeting last week, the CDC’s advisory committee reached the conclusion that it did not have enough data at the time of voting to offer age- or risk-based recommendations or recommendations for use (DID, April 15).

Meanwhile, J&J reportedly reached out to fellow COVID-19 vaccine rivals Pfizer, Moderna and AZ in the hopes of teaming up on a company-led investigation into blood clot risks. Only AZ reportedly agreed to collaborate.

Pfizer did not confirm the request or that it had declined it, but told FDAnews the company “embraces opportunities for scientific exchange when we can make a meaningful contribution that is not being represented by other groups or regulators” and adding that it will “continue to collaborate with other vaccine-makers as appropriate” during the pandemic. Moderna and AZ did not return requests for comment.

J&J came out with correspondence Friday arguing against a letter penned by University of Nebraska researchers, both of which were published in the New England Journal of Medicine. Responding to the researchers, who evaluated a single J&J vaccinee that experienced a rare blood clot and concluded the condition “could be related to adenoviral-vector vaccines,” J&J said there is not enough evidence at this time to establish a link between the safety incidents and its one-dose shot.

The drugmaker added that so far, the rare blood-clot incidents are not occurring in patients at a rate outside of what’s expected to be seen in the overall population. Further, the company noted substantial vector and spike-protein differences between its shot and AZ’s adenoviral-vector vaccine that may cause the vaccines to provide “quite different biologic effects.”

The EMA is also conducting an evaluation of blood clots in connection with the J&J vaccine and said it expects to offer a recommendation this week. Europe, where vaccination efforts have seen numerous setbacks, faced yet another delay due to the blood-clot concerns, with J&J temporarily halting shipments just after it had begun its first vaccine deliveries within the bloc (DID, April 13). — James Miessler