Tianjin has raised a residential community to high risk level for contracting COVID-19, after four local residents tested positive for the virus.
Among the four cases reported early Friday morning, three are from a family in Kanhaixuan community, Dongjiang port area.
All of the four people took nucleic acid tests on November 10 and returned negative results, after one asymptomatic case was found in the residential community.
They received another round of nucleic acid tests and serum antibody tests that were carried out among residents in the community on November 18. Notably, all four returned positive nucleic acid test results but three returned negative serum antibody test results.
The residential community, a kindergarten and the Taida Hospital, which are related to two of the four reported cases, have been put under closed-off management. Close contacts of the cases have been put under quarantine as well, Tianjin authorities announced.