Traffic control on Nan'ao Bridge, which links the island county to the mainland of Guangdong province, has been imposed and vehicles are not able to enter the island through the bridge.
The restriction was imposed until further notice to help prevent COVID-19 from spreading to the mainland after eight fishermen were detected to be imported asymptomatic carriers in the county. The county, administered under Shantou in the eastern part of Guangdong, made the announcement on Saturday.
The eight infections have now been transferred to a designated hospital for medical observation and treatment.
Government departments have launched county-wide nucleic acid tests to trace possible infections in the county while making efforts to disinfect the venues where the infected people have visited.
Ten fishermen from the same fishing boat returned to shelter in Nan'ao in the early morning on Thursday after they had been at sea for about three months.
Eight tested positive coronavirus in a routine screening on Friday. The samples collected from the boat have tested negative. The fishermen went ashore once for shopping before the positive tests.
Nan'ao, covering an area of about 114.74 square kilometers, is the only island county in Guangdong.
The county is composed of the main Nan'ao island and a surrounding archipelago.