This model is based on interferon-induced resistance to infection of respiratory epithelial cells and the clearance of infected cells by natural killers with seven state variables (the numbers of healthy (UH), partially infected (UE), infected (UI), and resistant-to-infection cells (UR) and IFN-I molecules ([IFN]), natural killer cells (K), and virus particles (V)). Here, IFNA1 is linked to infection.