Following the announcement by President Trump that he is taking hydroxychloroquine, many people have been searching for evidence for hydroxychloroquine for coronavirus infections to see if there is a case for using the drug as a prophylactic to prevent infection or to reduce the severity of COVID-19 if an individual is infected with SARS-CoV-2.
Hydroxychloroquine has been used to reduce inflammation in patients with malaria and the drug is also used to treat rheumatic diseases such as lupus to reduce inflammation, pain and swelling.
The evidence for hydroxychloroquine as a treatment for COVID-19 is currently thin. Some studies suggest the drug may reduce viral load, shorten hospital stays, and even help to prevent infection but virtually all of the studies conducted so far have either been flawed or the study sizes have been far too small to allow any firm conclusions to be drawn about the effectiveness of hydroxychloroquine for treating coronavirus infections.
One study conducted in China suggested chloroquine, which is closely related to hydroxychloroquine, was a promising drug for treating COVID-19 and other in vitro studies have shown hydroxychloroquine was effective against SARS-COV, but whether the drugs would also be effective in vivo remains to be seen.
Two studies conducted by researchers in France – Hydroxychloroquine and azithromycin as a treatment of COVID-19: results of an open-label non-randomized clinical trial – DOI 10.1016/j.ijantimicag.2020.105949; Clinical and microbiological effect of a combination of hydroxychloroquine and azithromycin in 80 COVID-19 patients with at least a six-day follow up: an observational study – suggested there were lower numbers of patients testing positive for COVID-19 when they took hydroxychloroquine, either on its own or in combination with the antibiotic azithromycin. One of the studies had a control group, but it was not randomly selected, and the results of the study have been questioned as the analysis of the results did not include all patients who received the treatment. Notably, the four patients with poor outcomes were not included in the analysis. The second study did not have a control group. Both of the studies were small, the first having 26 patients and the second had 80.
A study conducted in China on 62 patients with mild cases of COVID-19 found that patients who were treated with hydroxychloroquine had a shorter recovery time than the control group and the results were statistically significant – Efficacy of hydroxychloroquine in patients with COVID-19: results of a randomized clinical trial – DOI: 10.1101/2020.03.22.20040758. This was a randomized study with a control group, but the study was small and patients with severe symptoms were not included in the trial. The researchers were only able to partially confirm that hydroxychloroquine could be used as a treatment for COVID-19.
There are also potential side effects, including an increased risk of heart arrhythmias. One trial conducted in Brazil in April had to be halted due to the high rates of heart arrhythmias and patient deaths, and even this trial didn’t include a control group so they were unable to confirm that the doses used caused the heart arrhythmias.
One randomized clinical trial conducted in China and published in The BMJ on May 14, 2020 – Hydroxychloroquine in patients with mainly mild to moderate coronavirus disease 2019: open label, randomised controlled trial DOI: 10.1136/bmj.m1849 – found that patients with mild to moderate, persistent COVID-19 that received treatment with hydroxychloroquine did not clear the virus any faster than patients given a placebo, but there were more adverse events in the group that received hydroxychloroquine.
A second study, conducted in France and published in the BMJ on May 14, 2020 – Clinical efficacy of hydroxychloroquine in patients with covid-19 pneumonia who require oxygen: observational comparative study using routine care data. DOI: 10.1136/bmj.m1844 – found no meaningful difference between patients receiving the drug and those that received standard care. The French study was conducted on patients admitted to hospital with COVID-19 pneumonia who needed oxygen.
Many more studies are now being conducted to assess the effectiveness of using hydroxychloroquine for coronavirus infections, but until larger, high-quality randomised clinical trials are conducted, peer-reviewed, and published, the jury is still out on the effectiveness of hydroxychloroquine for coronavirus infections such as SARS-CoV-2.