Nasal irrigation efficiently attenuates SARS-CoV-2 Omicron infection, transmission and lung injury in Syrian hamster model.

Recently, a new variant lineage of SARS-CoV-2, namely Omicron, becomes the dominant global circulating strain. The multiple antigenic mutations of Omicron largely decrease the efficiency of current vaccines and neutralizing antibodies, which necessitates the search for more potent and reachable medical countermeasures. Here, we hypothesize that direct viral clearance by nasal irrigation might be a convenient and alternative option, and perform proof-of-concept experiments in Syrian hamster model. Interesting, Omicron shows a different dynamic in the changes of viral RNA, viral titers and proinflammatory cytokines in nasal rinsing samples when compared with the prototype. Meanwhile, the levels of viral load and proinflammatory cytokines in nasal rinsing samples can indicate the severity of lung injury. Of note, daily nasal irrigation efficiently attenuate inflammation and lung injury in Omicron-infected hamster by decreasing the viral loads in respiratory tract organs. Moreover, daily nasal irrigation effectively suppresses viral transmission by close contact.