The head of the World Health Organization (WHO) warned Monday that the “worst is yet ahead us” from the novel coronavirus outbreak.

WHO Director General Tedros Adhanom Ghebreyesus said in a video conference that the world must act together on a national and global scale to overcome the pandemic.

He reiterated his calls for global solidarity and national unity and warned that if this does not happen, more people will die.

“Without these two, believe us -- the worst is waiting for us. Let’s prevent this tragedy. This is such a virus that many people haven't understood it yet,” he said.

“This virus has new types of contagion habits. It is very contagious just like the flu. It’s a serious killer like SARS and MERS. It has dangerous combinations.”

He also denied US claims that the WHO hid information from member countries.

After originating in Wuhan, China last December, COVID-19, the disease caused by the novel coronavirus, has spread to at least 185 countries and regions worldwide, with Europe and the U.S. the worst-hit regions.

There are more than 2.4 million cases worldwide and over 170,000 deaths. More than 647,000 have recovered from the virus, according to data compiled by US-based Johns Hopkins University.

Despite the severity of the virus, most people experience mild symptoms and recover in due time.