Almost all deceased victims are drown by mucus accumulated at bottom of lung "sponge", where air is supposedly to fill alveoli, but then is unfortunately crammed by viscous mucus. The obvious comparison by chest X-ray images of normal & abnormal: 
Even ventilator is hooked up, patients, up to 80%, will still be died of mucus-drowning, because there would be no way to infuse oxygen through phlegm plug. For a health or so-so subhealth person, lung-bottom mucus can be pumped by arrays of cilia to upper respiratory tract, then will easily be spit out by cough. But for a COVID-19 patient, cilia is too weak to wigglingly pump its surrounding liquid waste or mucus, which most elements are those dead cells + new generations of virus, then mucus get thicker, and coughs futilely bring out nothing. 
There is about 30cm from throat to bottom of lung, so the pump pressure differential should be above 0.44 psi or 3 kpa, and there is no problem for the normal workable cilia-micro-pump arrays along mucus transportation way. Even in difficult situation with failed biologic pump, there is always an energy-free pump ready for use, i.e. the gravity pump, and it is accessible at home, if one have this fitness tool: 
By upsidedowning patient body | torso, now the accumulated mucus can naturally flow downwards from bottom of lung to throat, if mucus viscosity is agreeable. For patients in severe phase, thick mucus may be not in flowable condition, so before using the tool, special measure should be taken by inhalation of thinning vapor, such as acetylcysteine, alcohol, even simple water vapor. Following picture shows ultrasonic vaporizer with face mask, and for best efficacy, acetylcysteine or alcohol has to be solved in solution, then load into cartridge. 
Above picture shows a regular heated humidifier, and handy guys can customize a hose + mask to couple with face. Even can hot mist alone liquify effectively the slimy mucus, and deactivate virus in somewhat degree though not 100% kill. Still failed to find a vaporizer or mist generator around any corner of your home? Anyway, perhaps you are an e-cigarette smoker, but now please no longer use it for regular pleasure, just go to repurpose it for vaporizing acetylcysteine solution. 
Even in very severe stage and no chance to be supported by ventilator or ECMO in hospital, patients can still survive by exercising above DIY procedure. As long as lung bottom mucus is drained, easy respiration + good food will support patient to eventually conquer coronavirus with expectable forthcoming antibody generation. Synthesis of antibody will consume lots of protein, therefore patients must eat enough eggs, fishes, porks, beefs or other meat with high protein content, and force yourself to eat, even without any appetite. Despite high death risk with treatment by ventilator in hospital, but if using 3-way hose fitting to add inlet of acetylcysteine-dispersed hot mist for declotting phlegm-plugs, then death risk will be greatly reduced, as illustrated below: 
Last but not least: Prevention is always the better choice than above relieving exercise, and more simpler. My earlier article introduced a preventive method: I even have a free invention to fight COVID-19:
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