Hydroxychloroquine studied vs Vitamin C (PBO) prophylaxis to households (n=671) exposed to COVID-19. 89% were COVD1-9 test neg at baseline. HCQ did not protect against progression to COVID (53 vs 45 events; adj HR, 1.10 [95% CI, 0.73 to 1.66]. A vit C Win! https://t.co/S5qjdIYaXq