CXCL8 and infection: The sprayed Bacillus spores significantly inhibited the multiplications of RSV (630 folds) and co-infection bacteria S. pneumoniae and H. influenzae (103–104 folds), thereby reducing the overreacted immune response of epithelium cells to lower IL-6, IL-8, TNF-α pro-inflammatory cytokine levels (2.7–12.7 folds) in nasal tract.