evidence: 'No Clear Evidence' Hydroxychloroquine Works Against COVID-19 (washingtonpost.com) 548 "There is no clear evidence that the drugs work against the coronavirus," he writes, "despite their use by hospitals and doctors in the United States and other countries since the outbreak began." Their antiviral properties have been proved in test tubes, but rigorous clinical trials to test their effectiveness in humans have not been completed. Limited studies on coronavirus patients have been published by researchers in France and China, but their extremely small size and other problems prevented them from being statistically significant. The French study included a combination of hydroxychloroquine with the antibiotic azithromycin that showed benefit in six patients... Another study in 11 patients in France showed no evidence the regimen works. A Chinese study also showed no benefit over the standard course of treatment. Mainstream scientists caution against using the drugs without more evidence they are effective... The dangerous side effects of the drugs are much better known. Most seriously, the drugs can trigger arrhythmia, which can lead to a fatal heart attack in patients with cardiovascular disease or who are taking certain drugs, including anti-depression medications. Doctors recommend screening with an electrocardiogram to prevent the drug from being given to the 1 percent of patients at the greatest risk of a cardiac event. The drugs also can cause vision loss called retinopathy with long-term use, and chloroquine has been associated with psychosis...