Many viruses require reduced sulfhydryl groups for cell fusion and entry. Corona viruses, including SARS-CoV-2 (the cause of the condition now named coronavirus disease 2019 or COVID-19), are rich in cysteine, which residues must be intact for viral activity. Sulfhydryl groups are vulnerable to oxidation. Ozone therapy, a very inexpensive and safe modality may safely exploit this critical vulnerability in many viruses, inclusive of SARS-CoV-2.