Countries across the world must take a comprehensive approach to fighting the pandemic of COVID-19 disease caused by the new coronavirus and isolate, test and trace as many cases as possible, the World Health Organization said on Wednesday.

"To suppress and control the epidemic, countries must isolate, test, treat and trace," the WHO's director general Tedros Adhanom Ghebreyesus told a media briefing.

"If they don't, transmission chains can continue at a low level and then resurface once physical distancing measures are lifted," he added. He said the test and trace strategy "must be the backbone of the response in every country".

Tedros also said that to speed the search for potential therapies and drugs for COVID-19 infection, the WHO and its partners are organizing a multi-country study to analyze and compare some as yet untested treatments.

"This large international study is designed to generate the robust data we need to show which treatments are the most effective," Tedros said. "We have called this study the solidarity trial."