The first red flag with this study is that the subjects who were enrolled and given "prophylactic" hydroxychloroquine were started on the drug within 4 days of diagnosis of their contact. The odds are very high that source of the infection was shedding virus for several days before that. Regardless, this a post-exposure pre-illness treatment for COVID. That still does not evaluate pre-exposure prophylactic use of the drug. Many people are already exhibiting symptoms by day 4 after exposure. That is what happens when peers review papers like this. They pick apart the information and point out the potential errors in the research or conclusions. This was great research but once again the information derived needs to be taken in the context of the methods.
IMO, the best way to determine efficacy would be to have people on hydroxycloroquine for a number of days THEN expose them to the virus via challenge. Would you like to volunteer for that study?
they are doing a pure prophylactic trial in Detroit - whip COVID or something like that