March 2020 the world’s largest supercomputer “SUMMIT,” comparing human receptors and the virus with known medicines and vitamins, predicted Quercetin would be in the top 5 tools to support the body’s natural protection of our angiotensin ACE2 system from spike proteins. Article
Nobel scientist Albert Szent-Györgyi who discovered Vitamin C, found that natural flavonoids like Quercetin, (originally named “Vitamin P”) were critical for Vitamin C to cure scurvy and later learned, have a number of mechanisms to support normal viral defence. Article
The multiple mechanisms for antiviral activity from studies with *other* viruses show Quercetin inhibitis virus entry to cells, inhibits virus replication, inhibits proteases, blocks virus assembly, increases T helper cells for immune system, and binds to spike glycoproteins to stop them attaching.
Quercetin treatment also displayed a beneficial effect in immunocompetent mice infected with Mengo virus, where it lessened the severity of organ damage (https://pubmed.ncbi.nlm.nih.gov/6127014/). Athletes supplemented with quercetin are protected from stress-induced susceptibility to upper respiratory tract infection (https://pubmed.ncbi.nlm.nih.gov/17805089/)
The data linking Quercetin with supporting normal defence against other viruses including coronaviruses and specifically including SARS COV strongly encouraged further studies.
This led to typical studies such as this one published in July 2021 with 100 people in a health clinic seeing covid patients every day before vaccines were available, where approximately half the group took quercetin, zinc and vitamins and the other half didn’t. The group who followed this regime had approximately 75% protection from infection and those who were infected were far less severe.
For further reading on the many mechanisms of Quercetin (Vitamin P) and Ascorbid Acid (Vitamin C) together against virus, please refer to the following summary.