Novavax flu vaccine matches and beats Sanofi rival in phase 3

A nurse preparing a medical injection
Novavax thinks new flu vaccine data give it "a clear path forward to licensure." (Getty/scyther5)

Novavax’s influenza vaccine NanoFlu has outperformed Sanofi’s Fluzone Quadrivalent on measures of immunogenicity in a phase 3 trial. The trial hit its primary and key secondary endpoints, sending Novavax’s stock up 40% and sparking talk of an accelerated FDA approval. 

NanoFlu is a nanoparticle flu vaccine that Novavax makes in its insect cell system. To gather the data it hopes will get NanoFlu to market, Novavax randomized 2,652 healthy adults aged 65 and older to receive either NanoFlu or Sanofi’s Fluzone Quadrivalent. Both vaccines featured the four strains used in prophylactics made for the 2019 to 2020 Northern Hemisphere flu season.

Novavax designed the primary efficacy endpoint to show NanoFlu is non-inferior to Sanofi’s vaccine in terms of immunogenicity. The study met that endpoint. 

Another primary endpoint looked at safety and tolerability. Novavax noted a “modest increase in local adverse events” but otherwise found NanoFlu was well tolerated with a safety profile in line with that of Sanofi’s established flu vaccine, setting it up to push ahead with plans to get the vaccine to market in the U.S. 

“With these data, we now have a clear path forward to licensure with our differentiated recombinant influenza vaccine. We expect that both Fast Track designation and the accelerated approval pathway from the FDA will help Novavax bring NanoFlu to market as quickly as possible to address the serious public health threat of influenza,” Novavax CEO Stanley Erck said in a statement.

The trial’s secondary endpoints sought to ascertain whether NanoFlu can beat, rather than simply match, Sanofi’s Fluzone Quadrivalent in certain areas. Novavax said NanoFlu achieved significantly higher geometric mean titers (GMT) and seroconversion rates (SCR) across all four strains. The differences in GMT and SCR topped out at 66% and 20 percentage points, respectively. NanoFlu also outperformed its rival when tested against four drifted H3N2 strains not found in this year’s vaccines.

Novavax used the data to argue its vaccine “overcomes issues related to egg-adaptation and antigenic drift.” Investors also responded positively to the readout, fueling a 40% jump in the value of the biotech in premarket trading.