Provided herein are methods for modulating immune responses to a respiratory viral infection (e.g., influenza, rhinovirus, coronavirus, or paramyxovirus) in a subject, wherein the methods comprise administering to the subject a compound (e.g., a PDE4 modulator or an immunomodulatory compound), or a pharmaceutically acceptable salt, solvate, hydrate, or stereoisomer thereof. Also provided herein are methods for treating, preventing, ameliorating, and/or delaying the onset of one or more symptoms associated with or resulting from a respiratory viral infection (e.g., influenza, rhinovirus, coronavirus, or paramyxovirus) in a subject, wherein the methods comprise administering to the subject a compound (e.g., a PDE4 modulator or an immunomodulatory compound), or a pharmaceutically acceptable salt, solvate, hydrate, or stereoisomer thereof.