Nanjing, Jiangsu province, reported a confirmed COVID-19 case on Monday on its WeChat account — a close contact of an imported asymptomatic case in neighboring Anhui province.

The COVID-19 control office of Nanjing’s Yuhuatai district received notice from Anhui province about the contact, surnamed Xiao, on Friday and immediately sent him to a quarantine center.

Xiao tested negative on Friday but was then found positive on Sunday. He has been transported to a designated hospital for treatment.

The man, who had not been vaccinated, traveled to Nanjing for business on Wednesday. Three of his close contacts have also been quarantined for observation.