The upper respiratory tract is continuously exposed to a vast array of potentially pathogenic viruses and bacteria. Influenza A virus (IAV) has particular synergism with the commensal bacterium Streptococcus pneumoniae in this niche, and co-infection exacerbates pathogenicity and causes significant mortality. However, it is not known whether this synergism is associated with a direct interaction between the two pathogens. We previously reported our approach to develop a gamma-irradiated IAV vaccine (g-Flu) capable of inducing cross-protective immunity mediated by cross-reactive cytotoxic T cell responses (1). In addition, we recently reported the development of a serotype-independent pneumococcal vaccine using genetically modified non-capsulated bacteria inactivated by gamma-irradiation (g-PN) (2). Furthermore, we reported that co-administration of g-Flu with g-PN enhances pneumococcal-specific responses (3). Our recent study shows that mucosal co-administration of g-Flu and g-PN similarly augments IAV-specific immunity, particularly Tissue Resident Memory cell (TRM) responses in the lung (4). In addition, our in vitro analysis revealed that S. pneumoniae directly interacts with both g-Flu and with live IAV, facilitating increased uptake by macrophages as well as increased infection of epithelial cells by IAV. These observations provide an additional explanation for the synergistic pathogenicity of IAV and S. pneumoniae, as well as heralding the prospect of exploiting the phenomenon to develop better vaccine strategies for both pathogens.