After the retraction last week of a controversial study published in British medical journal The Lancet, which said the old malaria drug that has attracted so much attention recently is in the best case useless and in the worst cases deadly, its merits or drawbacks in treating Covid-19 seem less clear than ever.

In an analysis of data from hospitalized patients that determined hydroxychlorquine did not help patients fight Covid-19, but did increase the risk for heart problems and death, the authors of the Lancet study funded by Brigham and Women’s Hospital in Boston initially concluded that the drug was not safe to use.

On that basis, the World Health Organization (WHO) temporarily removed the hoped-for treatment from its own trials, pending a review of safety data, and trials in Belgium and France were also halted as a precaution. The governments of those two countries banned the use of hydroxychloroquine in the coronavirus indication.

Soon after publication in the British journalquestions began to be raised about the reliability of the data analyzed, which led a week later to the retraction. In particular, European clinicians who had begun or were planning to conduct trials with the drug as a Covid-19 treatment were unhappy with the study’s findings. Some 180 doctors wrote an open letter criticizing it.

The critics’ beef was especially that the average daily doses of hydroxychloroquine detailed in the journal were higher than those recommended by the US Food and Drug Administration (FDA). The letter writers said also that data The Lancet reported from Australian patients did not seem to match data from that country’s government.

Another major concern was that the study’s authors from Brigham and Women's Hospital did not release their code or data despite signing a pledge to share information on the coronavirus, they said.

In a statement explaining the retraction, the Lancet wrote: “Today, three of the authors of the paper, ‘Hydroxychloroquine or chloroquine with or without a macrolide for treatment of COVID-19: a multinational registry analysis’, have retracted their study. They were unable to complete an independent audit of the data underpinning their analysis. As a result, they have concluded that they ‘can no longer vouch for the veracity of the primary data sources.”

The researchers at Brigham and Women’s Hospital acknowledged that they had obtained the data from Surgisphere Corporation, which, however, declined to publish its full dataset. For the same reason, the New England Journal of Medicine subsequently retracted a study on Covid-19 and cardiovascular health for which it used data from the same company.

Following the retraction, it was not immediately clear whether the trials that had been canceled would be resumed. Several larger clinical studies of hydroxychloroquine are still in progress in the US, at the National Institutes of Health, the University of Washington and Rutgers Cancer Institute in the state of New Jersey.

In the Rutgers study, patients suffering from Covid-19 will are being randomly enrolled in one of three groups: hydroxychloroquine alone, hydroxychloroquine and azithromycin, or supportive care for 6 days followed by hydroxychloroquine.

"We're looking to see if these drugs, alone or in combination, can actually lower the patient's viral load," said Steven K. Libutti, one of the lead researchers. First results could be available this month.

According to reports, the Rutgers trial with hydroxychloroquine in combination with the antibiotic azithromycin, is similar to the one in France touted by US president Donald Trump, but with a “more rigorous“design. The Surgisphere data showed azithromycin to be problematic.

None of the studies to date has been peer reviewed.