We will do it, but we REALLY do not recommend it.
Reason: Air duct work is made of Galvanized steel that has a protective coating from the factory. Fogging or disinfecting inside the ductwork may cause it to get moisture. In addition oh, this can create more problems with collecting dust from it sticking to the inside of your ductwork. Further any company claiming that the sanitize and disinfectant will kill a virus is wrong. Even after you disinfect, if the virus is in the air it can easily circulate again.