The present invention concerns the use of an alpha-glucosidase glycoprotein processing inhibitor for the treatment or prevention of human coronavirus infections, such as SARS-CoV-2 or SARS-CoV-2 variant infections. Aspects of the invention include methods for treating or preventing coronavirus infection, or a symptom thereof, by administering an alpha-glucosidase glycoprotein processing inhibitor, such as castanospermine, or a pharmaceutically acceptable salt, derivative, or prodrug thereof, to a human subject; methods for inhibiting human coronavirus infection in a human cell in vitro or in vivo; pharmaceutical compositions; packaged dosage formulations; and kits for treating or preventing human coronavirus infection.