AstraZeneca’s COVID-19 Vaccine Continues to Face Issues as EMA Set to Meet Again Over Blood Clots

AstraZeneca (AZ) responded to National Institutes of Health (NIH) concerns over its interim vaccine trial data by releasing its primary analysis results yesterday, but the embattled company’s two-dose shot faces intense scrutiny, with the European Medicines Agency (EMA) holding an expert meeting on March 29 to review possible links to blood clots.

Responding to NIH charges that AZ may have included outdated data in its release of results for the company’s late-stage U.S. vaccine trial (DID, March 24), AZ said updated results from its primary analysis showed a slightly lower overall efficacy — 76 percent — than the interim analysis’ 79 percent.

The primary analysis did confirm that the vaccine bestows 100 percent protection against severe infection and hospitalization. The vaccine also demonstrated 85 percent efficacy against symptomatic COVID-19 in participants age 65 and older — five percentage points higher than the interim analysis’ finding.

“Positive high-level results from the primary analysis of the phase 3 trial … in the U.S. have confirmed vaccine efficacy consistent with the pre-specified interim analysis announced on Monday,” AZ said Thursday. The data from the late-stage trial’s primary analysis will support AZ’s Emergency Use Authorization (EUA) submission set to be filed in the first half of April.

But AZ’s troubles are not over, especially in the EU, where it has received intense criticism from bloc officials for failing to deliver on its supply commitments. The vaccine, recently the focus of an EMA and UK investigation into reported blood clots in vaccinated patients, will be reviewed further by the EMA’s expert panel on Monday.

Though the EMA and UK’s Medicines and Healthcare products Regulatory Agency both concluded that the AZ vaccine is likely not associated with an increased risk of blood clots except possibly in extremely rare cases (DID, March 19), the EMA’s drug safety committee is continuing its investigation.

Though most European countries were satisfied with the findings and resumed vaccinations with AZ’s shot this week, Denmark, Norway and Sweden are still suspending inoculations until they learn more about the possible link between the vaccine and the blood clots.

And tensions flared once more between AZ and the EU after Italian police, at the behest of the bloc, investigated a Catalent plant in Anagni, Italy, last weekend and discovered 29 million vaccine doses there that were characterized as a “stockpile.”

Following the discovery, the drugmaker defended itself with a number of clarifications, explaining that 16 million of those doses are still awaiting quality control release. The remaining 13 million doses are intended for COVAX countries and are also waiting for quality control release. The doses, AZ contended, were not even manufactured at Catalent’s Anagni site, having been brought there from outside Europe to be filled into vials.

“It is incorrect to describe this as a stockpile. The process of manufacturing vaccines is very complex and time-consuming. In particular, vaccine doses must wait for quality control clearance after the filling of vials is completed,” AZ said.

Other than the shipments to COVAX countries, there are no exports planned for the doses located at the Anagni facility, AZ said. — James Miessler