The coronavirus death toll in China dramatically spiked on Thursday (February 13).
242 new deaths were reported in Hubei province the epicenter of the outbreak.
This figure is more than double the prior daily record, reported by China's health commission.
The reason could be because officials have adopted a new way to count infections.
But it was not immediately clear how the new methodology changed the results, nor why the death toll suddenly leapt up so high..
It was all the more striking after Wednesday (February 12) - when China reported its lowest number of new cases in weeks.
Officials say they have begun revising old data and suspected cases.
China state media said that officials will also start recognizing CT scan results to confirm infections.
Reuters reported last month a lack of kits to test for such an overwhelming number of people with symptoms may have delayed patients from being properly diagnosed.
What is clear is when scientists change the criteria, it makes it hard to compare results and to track this epidemic.
Thursday's numbers brings the total deaths in Hubei province alone to over 1,300.
The confirmed new cases also jumped by almost 15,000 - bringing the total to 48,000.
The World Health Organisation sent a team to China this week.
The head of the emergency program warned, "it's too early to predict it this is the beginning, middle or end of the epidemic."