Prolonged Infectivity of Murine Norovirus in Aerosols Suggests Potential for Airborne Transmission.

Norovirus is a highly contagious enteric virus best known for fecal-oral transmission, but increasing evidence suggests that airborne spread may also contribute to outbreaks. Aerosol transmission of norovirus can occur during episodes involving vomiting, diarrhea, or toilet flushing. To investigate this possibility, the infectivity of aerosolized murine norovirus (MNV) was evaluated over time using influenza A virus (H1N1), a well-established respiratory virus transmitted via aerosols, as a reference control. Aerosols with a mass median aerodynamic diameter of 2.38 μm were generated in a 220 L chamber and captured using gelatin filters. MNV infectivity decreased by 2.33 log10 within the first 3 hours but remained detectable for up to 9 hours, corresponding to a total reduction of 4.2 log10. In contrast, H1N1 exhibited a more rapid decay, with a 2.9 log10 reduction within 3 hours. Overall, these results indicate that MNV retains airborne infectivity for longer durations, supporting the plausibility of aerosol transmission during norovirus outbreak scenarios.