U.S. FDA Says Novavax Covid-19 Vaccine Linked to Myocarditis Days Before Critical Vote
The documents were released ahead of a June 7 meeting of the FDA’s Vaccines and Related Biological Products Advisory Committee. The agency indicated five of the six myocarditis/pericarditis cases were observed within two weeks of administration and four were in young men. There were almost 30,000 participants in the study, run between December 2020 and September 2021. Otherwise, overall efficacy was 90.4%, although lower, 78.6%, in people 65 years and older.
Data from the studies were prior to the Delta and Omicron variant surges, although the documents say, “based on the efficacy estimate in the clinical trial of this vaccine, it is more likely than not that the vaccine will provide some meaningful level of protection against COVID-19 due to Omicron, in particular against more severe disease.”
Novavax has stated that the number of myocarditis events in the study was “within the range of expected background cases…. Despite the wide availability of authorized or approved vaccines, the SARS-COV-2 pandemic is not well controlled in the U.S…. there remains a desire for vaccines that have been developed using well-understood technology platforms.”
Meanwhile, the company initiated a Phase III trial of its vaccine against the Omicron strain on May 31. This particular vaccine trial is of a bivalent vaccine that contains both NVX-CoV2373 and NVX-CoV2515. NVX-CoV2373 is the vaccine currently on the market in other countries and up for review in the U.S. The trial will last 10 months with initial results expected in the second half of 2022.
The Novavax vaccine uses an older, traditional type of vaccine manufacturing process where copies of the spike protein are grown in insect cells, purified and placed into nanoparticles with an immune-stimulating adjuvant. That is compared to the newer mRNA vaccines that package a segment of mRNA coding for the spike protein in a nanoparticle. Protein vaccines have been used in numerous other vaccines, such as for hepatitis B and shingles.
In a statement, Novavax Inc. said “there is insufficient evidence to establish a causal relationship” between the vaccine and heart inflammation.
“The data from our placebo-controlled studies show that overall, in our clinical development program, the rate of myocarditis was balanced between the vaccine and placebo arms (0.007% and 0.005%). Furthermore, in the post-crossover portions of our studies, the cases we have seen are all within the expected rate,” Novavax Inc stated.
“Based on our interpretation of all the clinical data supporting NVX-CoV2373, including over 50,000 participants in clinical trials, we believe there is insufficient evidence to establish a causal relationship. We will continue to monitor all adverse events, including myocarditis and pericarditis,” Novavax concluded.