evidence: The results of a retrospective study published in the Journal of the American Medical Association show that hydroxychloroquine is not effective against COVID-19 and is associated with cardiac arrest. [...] The FDA revokes emergency use authorization for chloroquine and hydroxychloroquine citing in a statement that the drugs are "unlikely to be effective in treating COVID-19 for the authorized uses." [...] Two weeks after revoking emergency use authorization of the drug, the FDA publishes a summary of safety issues tied to using hydroxychloroquine and chloroquine to treat patients hospitalized with COVID-19.