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For all of modern medicine’s advances, the immune system is still largely on its own when it comes to viruses: Of the 200 or so types that are known to infect humans, only about 10 have approved treatments, according to the science journalist Matthew Hutson.

The race is now on to make the coronavirus the 11th: With a vaccine at least a year away, an effective treatment may be the country’s best hope for making a recovery before next year. But how close are researchers to finding a drug that works? Here’s a look at where things stand.

The old drugs on the block

For weeks, President Trump — against the advice of public-health experts like Dr. Anthony Fauci — has been endorsing hydroxychloroquine as a treatment. Sold under the brand name Plaquenil, hydroxychloroquine has been used for decades to treat malaria, rheumatoid arthritis and lupus. (Mr. Trump himself has a small personal financial interest in Sanofi, the French drugmaker that produces Plaquenil.) But the truth is we don’t know yet whether hydroxychloroquine has any treatment value for Covid-19.

While one new study suggests the drug may speed the recovery of mild cases, as Denise Grady reports for The Times, it has yet to be peer-reviewed. Earlier studies were limited, inconclusive or seriously flawed.

Fortunately, there is a nationwide clinical trial underway at the University of Minnesota that may help clarify the matter in the coming weeks.

In the meantime, hydroxychloroquine should not be promoted lightly, Olga Lucia Torres writes for The Times. The hype Mr. Trump created around the drug has caused healthy people to hoard it, putting people like Ms. Torres, who depends on it to keep her lupus in check, at even greater medical risk during the pandemic. What’s more, hydroxychloroquine can have serious side effects: heart and retinal damage and even permanent blindness.