A panel of experts convened by the US drug regulator on Tuesday recommended the Novavax Covid-19 shot, a late runner in the fight against the virus that could nonetheless play a role in overcoming vaccine hesitancy.
Three vaccines are currently approved in the United States: Pfizer and Moderna, which are based on messenger RNA, and Johnson and Johnson, which recently received a recommendation against broad use becase of links to a serious form of clotting.
Experts voted 21 in favor of the Novavax vaccine, with none against, and one abstention, despite some concerns it may be linked to rare cases of heart inflammation.
The Food and Drug Administration, which called the meeting, is expected to issue an emergency use authorization soon. Then another agency, the Centers for Disease Control and Prevention, will weigh in with guidance on how it should best be used.
Maryland-based Novavax was an early frontrunner in the global vaccine race, but fell behind after being hit by manufacturing and regulatory delays.
The US was one of the few major markets where it hasn't yet received authorization, while the EU, UK, Canada, Australia are among many that have already given it the green light.
Officials hope that the shot, which is based on lab-grown viral proteins, could provide an alternative for people still hesitant of the mRNA technology. It also doesn't have the same cold storage requirements as Pfizer and Moderna's shots.
"There really is a population of patients who are willing to take this and not going to take existing vaccines. I think it's pretty compelling," said Eric Rubin, an infectious disease specialist who participated in the meeting, explaining his vote in favor.
Of the various vaccine technologies, mRNA has been subject to the most misinformation efforts.
- Possible myocarditis link -
Novavax's vaccine was found to be more than 90 percent effective against symptomatic cases of the disease. But its trial was conducted long before the currently circulating sub variants of Omicron were dominant, and the company may yet have to add a booster or update its shot.
What's more, six cases of myocarditis, an inflammation of the heart muscle, were detected in the group that received the vaccine, against one case in the placebo group, in a trial of around 40,000 people.
Novavax says there is insufficient evidence to establish a causal relationship between the cases of myocarditis and the vaccine.
Such a link has been established with mRNA vaccines, but it only became apparent when they were used on millions of people in the real world, rather than tens of thousands in a trial.
The FDA voiced concern over the myocarditis link on Friday, and a warning is likely to be included on the eventual label. Earlier, trading in Novavax shares on Nasdaq was halted pending the meeting.
Known as a protein subunit vaccine, Novavax is administered in two doses.
It is based on a lab-created version of the spikes that dot the surface of the coronavirus to evoke an immune response.
The company uses a modified spike gene inserted into another kind of virus, called a baculovirus, which is used to infect moth cells, which then produce the spikes on their surface. These spikes are harvested and assembled into nanoparticles, which are injected into patients.
A compound of soapbark tree is added to the vaccine to heighten the response.