Provided is a method for preventing, alleviating, or treating a viral infectious disease or a respiratory disease, comprising administering a composition containing vesicles derived from Lactobacillus paracasei as an active ingredient to a subject in need thereof, wherein the vesicles may be orally administered and delivered to the lung to suppress a respiratory disease, administered to a COVID-19 virus- or influenza virus-infected model to suppress the replication of the COVID-19 virus and clinical symptoms caused by the influenza virus.