Nontoxic outer membrane vesicles efficiently increase the efficacy of an influenza vaccine in mice and ferrets.

•The fmOMV–adjuvanted vaccine showed protective effect of the in animal models.•The fmOMV with vaccine provided an efficient protection against virus challenges.•The fmOMV–adjuvanted vaccine induced Th1-type immunity.•fmOMV seems to be a promising candidate T cell adjuvant for the influenza vaccine.