Covid absolutely spreads through HVAC. In Florida heat, people go inside for ac to cool down. Very little outside air goes in the the ac so it circulates inside air which is not as big an issue in a private home as it is in a corporate or any public setting. So even if you are socially distant at work, you can still breathe particles of disease from others.
The use of germicidal lamps, a proven technology that works to kill Covid. The lamps are set up to shine horizontally, high in the room where sterilization is needed. Air currents, stirred in part by warmth from human bodies, circulate up to the ceiling, where the ultraviolet light kills floating pathogens, and then back down again. How safe is this? Video below.
Putting UVC lights in your air vents is the same idea and fairly inexpensive.