I have a uv-c light installed in my duct work facing my Hepa filter.
The concept of this is to use UV light in occupied spaces rather than filtering the air in the HVAC system though this is good (this light can be far more intense than what is safe for human skin and eyes.)
But to keep the power levels down low enough for it to be used in room lighting, apparently it takes 20 to 30 minutes to deactivate flu and presumably Corona virus.
Efficacy of vacuum-ultraviolet light disinfection...
https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-020-4847-9