This Week In Wellness a review published in the Biomolecules journal has suggested that melatonin may be more effective in reducing long covid symptoms and COVID-19 inflammatory markers than commonly used antivirals. The authors have suggested that the reason it has not been promoted more as a solution is due to its easy availability and the fact that it cannot be patented by pharmaceutical manufacturers. 

https://www.news-medical.net/news/20221109/Melatonin-could-be-a-potential-therapy-for-long-COVID-symptoms.aspx.

https://www.mdpi.com/2218-273X/12/11/1646.