The four individuals were diagnosed with pneumonia on Thursday and are in stable condition, the Wuhan Municipal Health Commission said in a statement published shortly after midnight.

Saturday’s statement marked the first confirmation of new cases by officials in nearly a week and came a day after the commission confirmed the death of a second patient.

Coronaviruses usually cause mild to moderate upper-respiratory tract illnesses, such as the common cold, but can also affect the lower-respiratory tract, causing pneumonia or bronchitis.

Chinese authorities said 45 people in the country had contracted the virus, with the outbreak centred around a seafood market in the central city of Wuhan, which is home to 11 million people.