Moderna’s post-Covid prospects dim

Moderna’s flu vaccine, a crucial plank underpinning its post-pandemic strategy, has disappointed – and the main problem is not, as might have been expected, its side-effect profile. Compared with an approved seasonal flu vaccine in its phase 3 immunogenicity trial, mRNA-1010 more or less worked on influenza A variants, but missed entirely on the less common B strains. Safety does remain a worry, with 70% of mRNA-1010 recipients reporting solicited adverse reactions versus 48% in the comparator group. Moderna’s share price dropped 5% in early trade. mRNA-1010 has another chance: Moderna is also conducting a much larger efficacy trial with an updated version of the vaccine designed to improve immune responses against influenza B. An interim efficacy analysis of this trial will occur by the end of next month, though chances of stoppage for efficacy at that point now seem low. But there is a bigger question: might reactogenicity be a problem for Moderna’s entire platform? With several flu jabs in the clinic, including combination Covid and RSV vaccines, Moderna has a lot to lose if so. And if the problem is common to all mRNA-based vaccines, Pfizer, Sanofi and GSK are in the danger zone too.