The W.H.O.’s study, called the Solidarity trial, enrolled more than 11,300 adults with Covid-19 in 405 hospitals in 30 countries. The participants were given four drugs singly or in combination: remdesivir, hydroxychloroquine, lopinavir, interferon or interferon plus lopinavir. About 4,100 received no drug treatment.

In the end, no drug or combination reduced mortality, the chances that mechanical ventilation would be needed, or time spent in the hospital, compared with the patients without drug treatment.

Several previous studies had pointed to the futility of hydroxychloroquine and lopinavir as treatments against the coronavirus. Less data has been published on interferon, a molecule produced by the immune system in response to viruses.

In their manuscript, the study’s authors called the overall findings “unpromising” and said they “suffice to refute early hopes” that any of the drugs tested “will substantially reduce inpatient mortality, initiation of ventilation or hospitalization duration.”