The present invention is directed to methods for treating a viral respiratory infection in a subject, preventing polymicrobial synergy in a subject, or preventing a bacterial infection in a subject. These methods include selecting a subject with a viral respiratory infection, a subject susceptible to polymicrobial synergy, or a subject susceptible to bacterial infection, respectively. In each case a therapeutic agent that inhibits interferon-gamma (IFNγ) is provided and administered to the selected subject under conditions effective to treat the viral respiratory infection, to prevent polymicrobial synergy, or to prevent a bacterial infection, respectively.