Budesonide as a nebulized aerosol for inhalation has been very effective in treating Covid. So is dexamethasone. But these drugs are available by prescription only in that form. My recollection was that the nebulized budesonide was quite expensive, about $500 without insurance. This is not something to fool with when you’re in your eighties. You should be telling your friends to seek medical care, not try to treat it themselves. Steroids, bronchodilators, and massive Rx doses of vitamins like C and D may be necessary. Zinc and melatonin may be helpful as well.