Health officials said they looked into past suspected cases and revised their diagnoses, suggesting older cases were also included in Thursday's numbers.
A total of 242 people died from the flu-like virus on Wednesday - the fastest rise since the pathogen was identified in December.
Amid the ongoing epidemic, Chinese authorities have reportedly relieved Hubei party secretary Jiang Chaoliang of his duties and appointed incumbent Shanghai mayor Ying Yong as the new secretary of the Communist Party of China, local media said Thursday.
Using quicker CT scans that reveal lung infections would help patients get treatment more quickly and improve chances of recovery, the Hubei health commission said.
There are now more than 60,000 cases of COVID-19 worldwide, with all but about 500 in mainland China.More news: New Zealand put India to bat in third ODI
In scientific and medical literature, COVID-19 has been referred to as 2019nCoV, certainly not a catchy name.
The latest figures from Hubei province will spark fears that an end to disruption in the world's second-largest economy is far from over.
But the World Health Organization warned it was too soon to declare victory.
The removals are the latest in a purge that saw Hubei's two most senior health officials fired earlier this week as criticism grows over the way the outbreak has been handled, with claims of under-reporting.
However, he emphasised caution, saying it was "far too early today to try to predict the beginning, the middle or the end of this epidemic".
Tests have been taking place to see whether antiviral drugs used to treat HIV are effective against the coronavirus - however, results are only expected in a few weeks.More news: United Nations underlines need for dialogue to resolve Israel-Palestine conflict
Tedros said a WHO-led advance team that traveled to China this week had made good progress on the composition and scope of its work.
Another cruise ship, the Westerdam, finally anchored Thursday off Cambodia after being turned away by several Asian and Pacific governments.
"Just seeing land was such a breathtaking moment", Angela Jones, an American tourist on the ship, told Reuters.
Dr Tedros also praised Cambodia for taking in the Westerdam, a USA cruise ship that had earlier been turned away from ports in Japan, Thailand and Taiwan despite having no sick patients on board.
The biggest cluster of cases outside China is on a cruise ship quarantined off Japan's coast, where 44 more people tested positive for COVID-19, raising the total number of infections on the Diamond Princes to 218.
The ship, which is docked at the Yokohama Port in Japan, has been quarantined since 3 February.More news: China's Hubei Province Sees Surge in Virus Deaths As Tally Method Changes