The 44-year-old South Korean MERS patient flew from Seoul to Hong Kong on Tuesday before heading to the China's mainland by bus. He is thought to have contracted the deadly virus from his father and brother, and traveled against the advice of doctors.
He has got fever but is in stable condition, according to the commission.
He was confirmed as China's first imported MERS case, is currently being held in isolation at a hospital in Huizhou in China's southern province of Guangdong.
MERS was first identified in humans in 2012. The virus is similar to that which causes Severe Acute Respiratory Syndrome, or SARS.
The World Health Organization has reported more than 1,000 cases of MERS globally and more than 400 deaths.