This following article(not peer reviewed yet, in pre-print) is a
, placebo-controlled, study which gave hydroxychloroquine (HCQ) or placebo to people who were exposed to COVID-19. In addition, it divided the exposure in early (0-3 days from exposure) and late (4 days or more from exposure) and by age.
The results show that there may be an statistically significant difference favoring HCQ use in post exposure prophylaxis of people younger than 45 years old and who started HCQ early.