In a case like this where the virus causes viral pneumonia, shortness of breath, etc, basically all the various diseases you're predisposed to if smoking, so that shortness of breath becomes a lot worse, and the little hairs in your airways have been molested by smoking, so there's not much debris/mucus transport happening out of the lungs. Viral pneumonia will most likely be joined by a bacterial pneumonia when you fail to ventilate your lungs properly.

People worry about Corona virus killing 2-5%, and yet smoking kills about 50%, with an individual risk of dying at about 300% of a non smoker.