An influenza mRNA vaccine protects ferrets from lethal infection with highly pathogenic avian influenza A(H5N1) virus

Highly pathogenic avian influenza (HPAI) A(H5N1) continues to spread throughout domestic poultry and cattle, with occasional transmission to humans. Although human-to-human transmission has not yet been reported, steps need to be taken to prepare should that occur. Here, Hatta et al. report preclinical testing of mRNA-based vaccines against HPAI. The vaccines, which are based on A(H5) clade 2.3.4.4b viruses, conferred protection in ferrets subsequently challenged with A(H5N1). Serum from vaccinated ferrets also neutralized an HPAI A(H5N1) isolate collected from an infected human in 2024. These data support further development of mRNA-based HPAI A(H5N1) as a means of pandemic preparedness.