The World Health Organization (WHO) has sent a clear message to countries around the globe on the COVID-19 pandemic:‘test, test, test’.

At a press briefing Monday on the new coronavirus, WHO Director-General Tedros Adhanom again urged countries to check more people for the virus, isolate and treat those infected.

"The most effective way to prevent infections and save lives is breaking the chains of transmission," said Tedros Adhanom.

"And to do that we must test and isolate. You cannot fight a fire blindfolded. And we can't fight this pandemic if we don't know who is infected."

The WHO chief also expressed concern about the virus reaching low-income countries.

"As the virus moves to low-income countries, we are deeply concerned about the impact it could have among populations with high HIV prevalence or among malnourished children.

"That's why we're calling on every country and every individual to do everything they can do to stop transmission," said Adhanom.