Update 29 May: The drug manufacturer, Sanofi, has temporarily stopped recruiting new COVID-19 patients for two clinical trials on hydroxychloroquine and will no longer supply it to treat COVID-19 while safety concerns are investigated.
Meanwhile, a coalition of concerned scientists wrote to The Lancet about the study recently published showing the drugs had no benefit and may have significant safety issues s (see News below 22 May.) The scientists asked the journal to provide details about the data used and requested the study to be independently validated by the World Health Organization or another institution.
Update 25 May: The World Health Organization (WHO) announced they are temporarily suspending testing of hydroxychloroquine in COVID-19 patients due to safety concerns. The drug had been one of several being tested in their Solidarity trial initiative. Potential benefits and harms will be reviewed by the safety monitoring board.
Update 22 May: A study published in The Lancet showed no benefit to using these drugs: "We were unable to confirm a benefit of hydroxychloroquine or chloroquine, when used alone or with a macrolide, on in-hospital outcomes for COVID-19. Each of these drug regimens was associated with decreased in-hospital survival and an increased frequency of ventricular arrhythmias when used for treatment of COVID-19."
Update 27 April: Canadian officials also warned that these drugs can cause serious side effects and should not be taken without medical supervision. For clinicians, they stated, "Investigational use of approved therapies like hydroxychloroquine and chloroquine should be done in the context of a well-designed clinical trial."
Posted 24 April: A statement issued today warns that chloroquine and hydroxychloroquine - two anti-malarial drugs that are being evaluated for treatment of COVID-19 - should only be used in hospitals or clinical trial settings, due to their risk of causing problems a patient's heart rhythm. The US Food and Drug Administration (FDA) warned the medications can cause abnormal heart rhythms, especially in people who already have heart issues, and the alterations can be fatal. This concern is heightened if the medicines are given with the antibiotic azithromycin, which can have a similar effect on heart rhythms. The FDA warned that the medications are only authorized for use against COVID-19 when given in a hospital. They added, "Hydroxychloroquine and chloroquine have not been shown to be safe and effective for treating or preventing COVID-19." The warning was partly based on a study in JAMA Network Open showing that, in a clinical trial, higher doses of chloroquine were associated with more fatal outcomes than lower doses of the medication when given to COVID-19 patients. The trial stopped giving the high-dose medication as a result of this data and is now giving the lower dose only.