In February 2023 Moderna announced interim results from its Phase III safety and immunogenicity trial of mRNA-1010 (P301). This mRNA-based seasonal influenza vaccine was tested in adults over the age of 18 in the Southern Hemisphere. It achieved “superiority on seroconversion rates for A/H3N2 and A/H1N1” and “geometric mean titer ratios for A/H3N2”. Furthermore, it demonstrated “non-inferiority on geometric mean titer ratios for A/H1N1”. However, “non-inferiority was not met for either endpoint for the influenza B/Victoria- and B/Yamagata-lineage strains”.  

The vaccine in trial 

Moderna states that mRNA-1010 encodes for haemagglutinin (HA) glycoproteins of the four influenza strains recommended by WHO to prevent influenza. The trial was a randomised, observer-blind study, enrolling 6,102 adults across Argentina, Australia, Colombia, Panama, and the Philippines during the Southern Hemisphere flu season.  

“Participants were randomly assigned to receive either a single dose of mRNA-1010 or a single dose of a licensed seasonal influenza vaccine as a comparator.” 

Although it was “generally well-tolerated”, the results have been picked up by the media and described as “mixed”. Consequently, shares in the company dropped almost 6% in after-hours trading.  

A step forward 

Despite the market and media reaction, Dr Stephan Hoge, President of Moderna, described the results as an “important step forward” in the “development of mRNA-based influenza vaccines”. Acknowledging the “substantial burden of disease” that influenza causes, Dr Hoge is “encouraged by the safety and tolerability profile” as well as the “immunogenicity results against Influenza A viruses”.   

“While we did not achieve non-inferiority for the Influenza B strains which are more frequent in younger populations, we have already updated that vaccine that we believe could improve immune responses…and will seek to quickly confirm those improvements in an upcoming clinical study”.  

For more from Moderna on mRNA approaches to various threats at the World Vaccine Congress in Washington this April, get your tickets today.