.I cannot for the life of me expect a coil treated with anything...

.I cannot for the life of me expect a coil treated with anything that remains fixed to the coil ....killing virus in the air UNLESS that virus touches the surface of the treated coil.
so, as there is no guarantee that the air touches the coil. then there is NO guarantees the virus is dead.
And the cost is not cheap.
Expensive....and NO guarantee...
That is my take.
If it did kill the virus 100% then everybody , every business and home would get it done, even if it were expensive (and has to be done every year)