Here are a few more research articles on low-dose naltrexone and COVID.

-- Safety and efficacy of low dose naltrexone in a long covid cohort; an interventional pre-post study:
https://www.sciencedirect.com/science/article/pii/S2666354622000758
-- Repurposing low-dose naltrexone for the prevention and treatment of immunothrombosis in COVID-19:
https://academic.oup.com/ehjcvp/article/8/4/402/6530643
-- Naltrexone a potential therapeutic candidate for COVID-19:
https://www.tandfonline.com/doi/full/10.1080/07391102.2020.1820379