In total, revealed more than 14 thousand new patients.
WHO DG has said that getting a new vaccine for COVID-19 can still take few months' time.
China on Thursday reported 254 new deaths and a spike in virus cases of 15,152, after the hardest-hit province of Hubei applied a new classification system that broadens the scope of diagnoses for the outbreak, which has spread to more than 20 countries.
"This outbreak could still go in any direction", he told a briefing in Geneva.
China's anti-corruption body said Hubei health commission chief Zhang Jin and director Liu Yingzi had been sacked for unspecified reasons and their roles would be filled by Wang Hesheng, a member of the provincial committee of the Communist Party, Reuters reported.
The total deaths in mainland China since the outbreak began in December stood at 1,367, with the total number of confirmed cases mounting to 52,526. Its biggest bank, DBS, evacuated 300 staff on Wednesday after a case at head office.
China has ousted high-ranking officials in its Hubei province amid widespread outcry over the continuing coronavirus outbreak.
"This is an example of global solidarity we have been consistently calling for", World Health Organization chief Tedros said.
"Outbreaks can bring out the best and worst in people".
China's military is sending 2,600 additional medical personnel to Hubei to help with virus control efforts in Wuhan, state news broadcaster CCTV said on Thursday.
Anti-Chinese sentiment has also reared on social media.
Dozens of low-level health officials across the country have also lost their jobs for failing to contain the spread of the epidemic, which emerged from an illegal wildlife market in Hubei's capital of Wuhan late past year and has claimed more than 1000 lives.