Confirmed COVID-19 cases worldwide has surpassed half a million with more than 20,000 deaths, the chief of the World Health Organization (WHO) said Friday, calling them "tragic numbers."

The situation dashboard by WHO showed a total of 509,164 coronavirus cases have been reported globally as of 10:00 CET Friday, as the virus spread to more than 200 countries and regions.

The global death toll from COVID-19 has risen to 23,335.

Noting that a COVID-19 vaccine is still at least 12 to 18 months away, WHO Director-General Tedros Adhanom Ghebreyesus Tedros stressed an urgent need for therapeutics to treat patients and save lives.

Speaking of the "Solidarity Trial," a multi-country clinical study for potential treatments for COVID-19, Tedros said it is a historic trial that will dramatically cut the time needed to generate robust evidence about what drugs work.

Tedros announced that the first batch of patients in Norway and Spain will be shortly enrolled in the clinical study, which compares the safety and effectiveness of four different drugs or drug combinations against the epidemic.

"The more countries who join the trial, the faster we will have results," Tedros said, noting more than 45 countries and regions are contributing to the trial while more have expressed interest.

Tedros, meanwhile, called on individuals and countries to refrain from using therapeutics that have not been demonstrated to be effective in the treatment of COVID-19.

"As the pandemic evolves and more countries are affected, we are learning more and more lessons about what works and what doesn't," Tedros said.

He underlined the necessity to follow the evidence, saying that there are no short-cuts.