I doubt increasing salt intake will do much to change the salt level of the mucosa in the upper respiratory tract, but I've become a big believer in nasal irrigation over the past couple of years (nasal sprays on the other hand never benefited me at all). Personally, hypertonic saline solutions kill me and cause inflammation. I use a hypotonic saline solution with added xylitol to make it hyperosmotic, and the salt I use includes potassium and calcium chloride to increase the chloride levels without burning. A recent trial showed the potential to reduce risk of hospitalization if patients began irrigating immediately after a positive PCR test. Povidone iodine solutions showed slightly more benefit, but saline solutions were nearly as effective.
Rapid initiation of nasal saline irrigation: hospitalizations in COVID-19 patients randomized to alkalinization or povidone-iodine compared to a national dataset
Objective To determine whether nasal irrigation initiated within 24 hours of a positive PCR test result reduces hospitalizations for COVID-19. Design, Setting and Participants Prospective case:cohort trial comparing clinical outcomes in patients aged 55 years or older who were PCR positive at a...