I’m been on the D3, C, Quercetin, Melatonin, Zinc, and NAC regimen since April 2020. I believe the NAC has helped my pulmonary function and reduced allergies to boot. My sinuses are more clear and its easier to get phlegm out of the lungs.
I used to get one to two colds per year and one of them would always progress to bronchitis which sometimes got really bad and usually took twelve weeks to cure. Since starting the regimen, nothing!
I also use a povidone-iodine gargle (Betadine) and nasal spray (Immunimist) at the first sign of a sore throat. Sore throats were always a reliable indicator that I was getting a cold.
I got vaxxed (Moderna) and one booster (Moderna). No COVID so far.
If nothing else, many of us have much better VitD levels, which will give us better health.
Agree on the NAC- even with reduced lung function my breathing is clearer and my sinuses haven’t bothered me even with wicked Florida spring pollen.