A new confirmed locally transmitted coronavirus infection was reported in Xi'an, Shaanxi province, on Thursday.
A medical worker serving quarantined patients at a designated hospital for COVID-19 tested positive, local authorities said.
The worker, surnamed Liu, 36, handled nucleic acid sampling and laboratory testing for patients in quarantine at Xi'an Eighth Hospital.
Liu began working in isolation wards on March 4 and has had no contact with people outside the hospital since then, according to the Shaanxi Health Commission.
Liu's nucleic acid test result was negative on March 11 and had a normal body temperature until Tuesday. Liu reported having a headache as the body temperature rose to 37.9 C on Wednesday morning. Another coronavirus test came back positive, and Liu is now getting treatment.
The hospital where Liu works has had eight imported confirmed COVID-19 cases and five asymptomatic carriers, all of whom were isolated. Experts said Liu was infected at work after being exposed to the coronavirus by accident.
All of Liu's other colleagues who began working at the hospital after March 4 have had no contact with people on the outside. They have been quarantined and are under medical observation, too. So far, their results have been negative. Samples from their living and working environments were taken, and those spaces were disinfected.
The Chinese mainland reported no new locally transmitted cases on Wednesday, the National Health Commission said on Thursday. But six new imported cases were reported on Wednesday.
As of Wednesday, 5,169 imported cases had been reported on the mainland. Of those patients, 5,001 recovered and were discharged from hospitals, while 168 remained hospitalized.