“No benefit was observed,” the researchers wrote in The New England Journal of Medicine.

The study tested Kaletra, a combination of two antiviral medicines, lopinavir and ritonavir, that are normally used to treat H.I.V.

There is no proven drug treatment for the new coronavirus, and doctors around the world have been desperately testing an array of medicines in hopes of finding something that will help patients, especially those who are severely ill. Several antiviral drugs have been considered possible treatments, though so far none has proved effective.

Even though the results were disappointing, the researchers said that this one study was not the last word, and suggested that more studies might determine whether the drugs would work if given earlier in the illness or in combination with other medicines.