Novavax goes before FDA’s Vaccines and Related Biologics Advisory Committee this week, seeking Emergency Use Authorization of its COVID-19 vaccine.

Pivotal phase 3 data found that the vaccine (NVX-CoV2373) was 90.4 percent effective against mild, moderate and severe COVID-19 disease, and 100 percent effective against moderate or severe disease. But pre-meeting documents show that the FDA is concerned about the three cases of myocarditis/pericarditis among more than 14,000 trial subjects — even though the link is unproven, and the observed rate is below what would be typically observed in this demographic.

In pre-meeting briefing documents, Novavax said the vaccine — which was first tested on the Alpha variant of SARS-CoV2 — is also highly effective against other variants of concern. The company estimated a 97 percent efficacy for variants closest to the original Wuhan strain, and 93 percent effective against variants with farther antigenic drift, including Epsilon and Delta.

The company will present a pooled safety analysis that includes overall mortality rates. Among almost 26,000 subjects in the pivotal trials, there were 16 deaths: 11 in the vaccine group and five in the placebo group. “None of the deaths were assessed by either the investigator or Sponsor as related to trial vaccine,” the briefing document said.

While Novavax hasn’t reported any cases of thrombotic events, there have been three cases of myocarditis and pericarditis. The FDA briefing document homes in on these cases, which represent 0.007 percent of the vaccine group (two subjects) and 0.005 percent of the placebo group (one subject).

Despite the tiny numbers, FDA’s briefing document for the June 7 meeting by the expert panel  makes note of this concern; the focus here suggests that committee members will be probing the issue quite seriously, searching for any signs of a causal link.

NVX-CoV2373 is not a messenger RNA vaccine. It consists of inactive spike proteins that are cultured from moth cells infected by a coronavirus.

The shot is already authorized in the EU, the UK, Canada, Australia and India, among other countries, and has won an Emergency Use Listing from the World Health Organization. It’s marketed as Nuvaxovid and Covavax.

Last spring, supply chain issues plagued manufacturing, but the Gaithersburg, Md.-based company said in March that those issues were resolved (DID, March 8).

Read the full briefing documents here: bit.ly/3NSJHBv. — Michele G. Sullivan