Scientific research paper from 2005:
https://virologyj.biomedcentral.com/articles/10.1186/1743-422X-2-69
I posted a link to that study back in spring 2020 and it got zero interest around here. When Trump mentioned HCQ later it must have come from that same study.
That 2005 experiment was done on Green Monkey tissue in a laboratory. It worked in the lab. But the SARS-1 virus had come and gone and there was no chance to try it out on infected people.
When Covid arrived there was plenty of opportunity to try it in vivo. They gave HCQ to nursing staffs as a prophylactic to see if it would protect them from becoming infected. They came down with covid at the same rate as nurses not taking HCQ. What works in vitro doesn’t necessarily work in live people.