Doxycycline? Why the hell should that help? It’s an antibiotic; they’re famously ineffective against viral infections – “please don’t pester your doctor for antibiotics to treat your cold”. I suppose it could help someone with severe covid if they’d picked up a secondary, bacterial infection.
OK J, an easy one. You say McCullough referenced all the data, so find and link the paper(s) showing that doxycycline is effective against covid-19.