evidence: The World Health Organization (WHO) doesn’t recommend hydroxychloroquine to prevent COVID-19. This suggestion is based on six trials with people who didn’t have the virus. Experts found that hydroxychloroquine had little or no effect on stopping these individuals from infection, hospitalization, or death from COVID-19. WHO also doesn’t suggest hydroxychloroquine as a COVID-19 treatment. Researchers did 30 trials with over 10,000 cases of COVID-19. Hydroxychloroquine didn’t lower the need for (or time using) ventilators or the risk of death. [...] Experts aren’t sure how hydroxychloroquine helps. They think it’s because the drug changes how your immune cells send signals. It can also turn off certain processes that cause inflammation.