Chloroquine and hydroxychloroquine during the COVID-19 pandemic

[28] Widespread administration of chloroquine or hydroxychloroquine, either alone or in combination with azithromycin, among COVID-19 patients, has been associated with increased mortality due to adverse effects, including QT prolongation.

[9][10] In October 2021 a large network of companies selling hydroxychloroquine and ivermectin has been disclosed in the US, targeting primarily right-wing and vaccine hesitant groups through social media and conspiracy videos by anti-vaccine activists such as Simone Gold.

[29] Chloroquine was initially recommended by Indian, Chinese, South Korean and Italian health authorities for the treatment of COVID-19,[30] although these agencies and the US CDC noted contraindications for people with heart disease or diabetes.

[2][38][39] In late March 2020, an Arizona man died of cardiac arrest and his wife was hospitalized after the couple ingested a version of chloroquine used as a parasite treatment for aquarium fish.

[40][41] Beginning in March 2020, New Jersey state senator Joe Pennacchio began publicly calling for the use of hydroxychloroquine to combat the spread of COVID-19 based on a French study which showed a decrease in "viral shedding.

[44][45] A Veterans Affairs study released results on 21 April suggesting COVID-19-hospitalized patients treated with hydroxychloroquine were more likely to die than those who received no drug treatment at all, after correcting for clinical characteristics.

[49] On 27 April 2020 the Association of American Physicians and Surgeons wrote a letter, signed by Jane Orient and Michael Robb, to Arizona governor Doug Ducey asking to rescind his executive order forbidding the use of hydrochloroquine as a treatment for COVID-19.

[51] On 5 June 2020, use of hydroxychloroquine in the UK RECOVERY Trial was discontinued when an interim analysis of 1,542 treatments showed it provided no mortality benefit to people hospitalized with severe COVID-19 infection over 28 days of observation.

[19] On 15 June 2020, the FDA revoked the emergency use authorization for hydroxychloroquine and chloroquine, stating that although the evaluation of both these drugs under clinical trials continues, the FDA (after interagency consultation with the Biomedical Advanced Research and Development Authority (BARDA)) concluded that, based on new information and other information discussed "... it is no longer reasonable to believe that oral formulations of hydroxychloroquine (HCQ) and chloroquine (CQ) may be effective in treating COVID-19, nor is it reasonable to believe that the known and potential benefits of these products outweigh their known and potential risks".

[20][52][53][22] On 23 July 2020, results were published from a multicenter, randomized, open-label, three-group, controlled trial of 667 participants in Brazil which found no benefit from using hydroxychloroquine, alone or with azithromycin, to treat mild-to-moderate COVID-19.

[54] In July, the U.S. President Donald Trump once again promoted the use of the drug contradicting various public health officials, including National Institute of Allergy and Infectious Diseases director Dr. Anthony Fauci.

[23] In August 2022, a meta-analysis led by Harvard epidemiologist Miguel Hernán found that the aggregate of pre-exposure prophylaxis trials with hydroxychloroquine suggested a reduction of around 28% in COVID-19 infections.

[59] Evidence of effectiveness in this setting was also provided by a large multicenter study led by the Centre for Tropical Medicine and Global Health at the University of Oxford, published only in 2024, which found a 15% decrease in symptomatic infections with prophylaxis.

On 22 May, The Lancet published a response to criticism of the Indian government's decision to allow chemoprophylaxis with hydroxychloroquine for some high risk persons who may have had exposure to COVID.

Researchers supporting prophylactic administration of hydroxychloquine note that results from human trials have suggested that hydroxychloroquine may decrease the duration of both viral shedding and symptoms if the drug is administered early.

10,000 National Health Service (NHS) workers, along with 30,000 additional volunteers from Asia, South America, Africa, and other parts of Europe are participating in the global study.

[73][74][needs update] Due to safety concerns and evidence of heart arrhythmias leading to higher death rates, the WHO suspended the hydroxychloroquine arm of the multinational Solidarity trial in May 2020.

Speaking at a press briefing, WHO's director-general, Tedros Adhanom Ghebreyesus stated that the board had reviewed the available mortality data and had found "no reasons to modify the trial".