"Now that the #coronavirus has a foothold in so many countries, the threat of a pandemic has become very real,” Tedros Adhanom Ghebreyesus was quoted as saying by WHO.
But he added that it could be the first controlled pandemic in history as decisions taken by governments, businesses and individuals could change the course it took.
“The bottom line is: we are not at the mercy of this virus,” Tedros Adhanom told reporters at a daily briefing.
The WHO chief also urged countries with community transmissions of coronavirus to consider measures that reduce exposure of more people to the virus.
"Depending on their context, countries with community transmission could consider closing schools, cancelling mass gatherings and other measures to reduce exposure," Tedros Adhanom said.
Different countries are in different scenarios and require a tailored response to what increasingly looks like a pandemic, but all should combine containment and mitigation measures, he said.
"All countries must take a comprehensive, blended strategy for controlling their epidemics and pushing this deadly virus back," Tedros Adhanom added.
The global infection tally passed the 100,000 mark over the weekend, with cases reported in more than 100 countries. More than 70 per cent of over 80,000 patients in China have already recovered, according to WHO.