DURING THE first two weeks of March, 20 patients suffering from the new coronavirus at a hospital in Marseille, France, participated in a preliminary study to see if the anti-malarial drug hydroxychloroquine had any effect on the disease, in some cases combined with an antibiotic, azithromycin. Sixteen people who didn’t get the drugs were enlisted as controls. After six days, the study found that 57.1 percent of patients who got hydroxychloroquine were cured, and 100 percent of those who got both drugs were cleared of the virus — compared to only 12.5 percent of the control group. Soon after it was published, this result was advertised by President Trump as “a real chance to be one of the biggest game changers in the history of medicine.”

Not so fast. Such success does not usually occur overnight. Widespread testing for drug safety and efficacy is essential. The French result does not mean this drug is ready for use against the coronavirus, nor should a world ridden with anxiety about pandemic illness and death rest its hopes on this unproven possibility. There may be a “wonder” drug at the end of the rainbow, but we are not there yet.

The French results, reported by Dr. Didier Raoult and colleagues in the International Journal of Antimicrobial Agents on March 20, were from a tiny group of people. Normally in the United States, a set of controlled clinical trials would be required before a drug is approved by the Food and Drug Administration: Phase 1 to determine overall safety and dosage; Phase 2 (about 100 people) to see if effective and safe compared with other compounds; Phase 3 (a large group) to test efficacy and side effects.

While hydroxychloroquine has already been approved for malaria, it has not been tested in this way for the coronavirus. Malaria is caused by a parasite, not a virus. Scientists are still arguing over how the drug attacks the malaria parasite. No one is sure how it might work against viruses. Besides, there are potentially serious side effects: irreversible retinal damage and cardiac failure in some patients.

Dr. Raoult reports that six patients who got both hydroxychloroquine and the antibiotic were cleared of virus as a result of a “synergistic effect of the combination.” But we don’t know what that is. Antibiotics often help prevent bacterial infection after a viral respiratory illness, but in this case, it will require research to know a “game changer” from a dud.

The most promising answer to the pandemic will be a vaccine, and researchers are racing to develop one. Mr. Trump’s inappropriate hype has already led to hoarding of hydroxychloroquine and diverted supplies from people with other maladies who need it. His comments are raising false hopes. Rather than roll the dice on an unproven therapy, let’s deposit our trust in the scientists.

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