Staff with the U.S. Food and Drug Administration (FDA) on Friday flagged the risk of heart inflammation following the administration of the Novavax COVID-19 vaccine, although they concluded the shot reduces the risk of mild-to-severe COVID-19.
In the company’s nearly 30,000 patient trial, conducted between December 2020 and September 2021, there were four cases of myocarditis, a type of heart inflammation also associated with mRNA vaccines, detected within 20 days post-vaccination. One patient in the trial reported myocarditis after receiving a placebo.
“These events raise the concern for a causal association with this vaccine, similar to the association documented with mRNA COVID19 vaccines,” FDA staff wrote in briefing documents that were released on Friday.
They continued: “Data from passive surveillance during post-authorization use in other countries also indicate a higher than expected rate of myocarditis and pericarditis (mainly pericarditis) associated with the vaccine. However, interpretation of these passive surveillance data is not straightforward, and further evaluation is needed to inform the risk of myocarditis and pericarditis associated with this vaccine, and their outcomes, as additional data emerge over time.”
The agency said it has asked Novavax to flag the risk of myocarditis and pericarditis, another type of inflammation of the heart, as an identified risk in its documentation. Data from Novavax’s trial was acquired before the Omicron and Delta variants spread across the world.
“Based on the efficacy estimate in the clinical trial of this vaccine,” the FDA staff wrote, “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.”