The province reported a total of 14,840 new confirmed cases on Tuesday, 13,332 of which were classified as clinical, bringing the total number of infected cases to 48,206 in the province.

This is the first time that the number of clinical cases is listed separately in addition to the previously two – suspected cases and confirmed cases – a classification that has resulted in the seemingly sudden surge of infected cases in the province.

So what exactly are 'clinical cases,' and what's behind the surge in Hubei?

Clinical cases are defined as suspected cases with CT images showing characteristics of viral pneumonia, including lung inflammation, according to the latest diagnosis and treatment program outlined by the NHC.  

"Previously, we mainly relied on nuclei acid tests to confirm whether a patient is infected with the virus. But actually, a large number of suspected patients in Hubei have exhibited typical symptoms and their CT images show characteristics of the epidemic," said Tong Zhaohui, Vice President of Beijing Chaoyang Hospital who's now in Wuhan.

"Doctors can usually make a conclusion based on these indicators whether the patient is infected, and these patients are called clinical cases," he explained.

Simply speaking, clinical cases are suspected patients who have not been tested positive for the virus in labs, but have exhibited symptoms very likely to be, according to Zeng Guang, chief epidemiologist at the Chinese Center for Disease Control and Prevention (CDC).

In other words, a large number of cases previously categorized as "suspected" are now clinical confirmations in Hubei, leading to the sharp uptick in total confirmed cases.

Why is this a separate category only in Hubei?  

The NHC said that singling out this category helps patients receive treatment as early as possible.  

The diagnosis and treatment program have been updated as scientists gain a better understanding of the virus. The latest version was published on February 9.

The new category of clinical cases was only added in Hubei because of the high numbers of suspected cases.