**Inhalation -> replication in epithelial cells of upper and lower airways (attaches via haemaglutinin spike and gains entry into cell) -> neuramidase alters efficiency of [[Respiratory System General Introduction - Pathology#Mucociliary escalator|mucociliary apparatus]] | **Inhalation -> replication in epithelial cells of upper and lower airways (attaches via haemaglutinin spike and gains entry into cell) -> neuramidase alters efficiency of [[Respiratory System General Introduction - Pathology#Mucociliary escalator|mucociliary apparatus]] |