Shenzhen reported no new local COVID-19 cases yesterday, and epidemiological investigations and source tracing of the city’s first Omicron case are being carried out, according to the health authority yesterday.

Gene sequencing found that the city’s first and single Omicron case, which was reported in Pingshan District on Sunday, was not in the same transmission chain as other Omicron cases in Tianjin, Shanghai, Zhuhai and Beijing, or previous imported cases in Shenzhen. But the virus strain involved was homologous to the genomes from North America in the global database, according to Lin Hancheng, a senior official of the municipal health commission.

The patient, a 21-year-old woman who works and lives in Longgang District, is mainly engaged in receiving and delivering overseas frozen chemical reagents. She touched and unpacked items of mail from North America without taking preventive measures Wednesday, and suffered from a sore throat Friday. She tested positive in a primary nucleic acid test Saturday. The possibility of the woman being infected after being exposed to contaminated international parcels cannot be ruled out, Lin said.

As of 5 p.m. yesterday, 284 close contacts and 278 secondary close contacts of her had been put under health monitoring. Key areas where she had dined and stayed, as well as public transport she had taken, have been sampled for environmental nucleic acid testing and disinfected, according to Lin.

In a separate development, Shenzhen reported one imported confirmed case and one imported asymptomatic infection yesterday. The confirmed patient is a Chinese national while the asymptomatic patient a Singaporean. They flew to Shenzhen from Singapore on Sunday and were placed under centralized quarantine upon entry. They were later transferred to the emergency wards of the Third People's Hospital of Shenzhen for treatment. Currently, they are in stable condition.