Hydrogen Peroxide, Infections and Your State-of-Mind by Dr. David Marquis

Hydrogen peroxide has been used since the end of the 18th century. It's very cheap, but don't confuse 'cheap' with 'ineffective'.
Dr. Marquis says that several of his colleagues in California have treated COVID19 patients with nebulized hydrogen peroxide and noticed excellent results.

Source: https://www.youtube.com/watch?v=TRqWVHnYleo