The Geneva-based WHO is leading a global initiative to develop safe and effective vaccines, tests and drugs to prevent, diagnose and treat COVID-19.
The respiratory illness has infected 4.19 million people around the world, according to a Reuters tally.
The World Health Organization said on Tuesday (May 12) that some treatments appear to be limiting the severity or length of the COVID-19 disease and that it was focusing on learning more about four or five of the most promising ones.
"We do have some treatments that seem to be in very early studies limiting the severity or the length of the illness but we do not have anything that can kill or stop the virus," spokeswoman Margaret Harris told a briefing, referring to the body's so-called Solidarity Trial of drugs against the disease.
"We do have potentially positive data coming out but we need to see more data to be 100% confident that we can say this treatment over that one," she added, saying more research was needed and planned.
Harris did not name the treatments.
Gilead Science Inc says its antiviral drug remdesivir has helped improve outcomes for COVID-19 patients.
Clinical data released last month on remdesivir raised hopes it might be an effective treatment.
Several studies looking at combinations of antiviral medicines have also suggested they may help patients fight off the virus.
The WHO official sounded a note of caution around expectations for a vaccine, however, saying coronaviruses in general are "very tricky viruses" that are "difficult to produce vaccines against".
More than 100 potential COVID-19 vaccines are being developed, including several in clinical trials.
The WHO said in April a vaccine would take at least 12 months.