Pfizer, BioNTech's combo mRNA shot is latest to be defeated by influenza strain B

Pfizer and BioNTech may have a strong pedigree in the mRNA vaccine game, but, when it comes to flu, they’ve run up against the same problem as their peers—neutralizing influenza strain B.

The two companies have been testing a combination flu and COVID-19 vaccine in a phase 3 trial. While the candidate did demonstrate sufficient immunogenicity against SARS-CoV-2 when compared to the companies’ own approved COVID-19 vaccine Comirnaty, it failed the trial’s other primary endpoint of triggering an immune response against both influenza strains A and B when compared to an unnamed approved flu shot.