Pre-existing heterosubtypic immunity provides a barrier to airborne transmission of influenza viruses

Human-to-human transmission of influenza viruses is a serious public health threat, yet the precise role immunity from previous infections on susceptibility to airborne infection still unknown. Using ferret model, we examined roles exposure duration and heterosubtypic transmission. We demonstrate that 48 hour sufficient for efficient H1N1 H3N2 viruses. To test pre-existing immunity, gap 8–12 weeks between primary secondary was imposed reduce innate responses ensure robust donor animals with found did not significantly block 2009 H1N1pandemic (H1N1pdm09) virus immune animals. Surprisingly, seasonal strains abrogated in recipient H1N1pdm09 immunity. This protection natural independent neutralizing antibodies. Pre-existing B transmission, indicating likely driven by adaptive response. can impact heterologous strains, implicate novel correlate limit spread respiratory pathogens through air.