Squirm; While yes, air systems are shared, modern offices (and homes) have filtered (though likely not HEPA filtered) positive pressure outlets and there is a central (hallway or more typically edge of building) negative pressure return.

While this virus does survive in aerosol form, it is not strictly airborne; This means that a non HEPA filter will likely stop it and that, from the return side; it's more likely to settle on the carpet or furniture than particularly infecting a human.

The more likely issue would be meetings of more than 1 person in a poorly ventilated room with no airflow; where aerosol virus would linger.