Medical staff conduct nucleic acid tests in Tianjin on January 22, 2022. Photo: VCG

North China's Tianjin Municipality reported four Omicron infections on Thursday after it claimed complete victory in curbing the variant in two weeks. The infections were caused by accidental exposure on a centralized quarantine, during which all results came back negative in the five rounds of tests.

The four infections confirmed on Thursday are relatives living in the city's Hebei district, with the carrier patient identified on Wednesday. The patient traveled to the Omicron-rampaged Jinnan district in early January and was put under centralized quarantine on January 10. 

He was isolated until 14 days after his last exposure to the virus and received five rounds of nucleic acid tests, all returning negative results, according to local health officials. 

On Wednesday, however, the patient went to a fever clinic for treatment where he tested positive for coronavirus. 

The four family members were immediately put under quarantine and test results returned positive indicating that all had contracted the virus. 

Analysis of the genome sequence of the Hebei district case showed that it belongs to the Omicron variant and is consistent with the infections found in Jinnan district, where the first outbreak occurred.

The latest spike that started on January 8 in Tianjin has recorded a total of 366 confirmed local cases and 22 asymptomatic infections, the authorities announced.

Some 362 close contacts and 513 secondary contacts of the confirmed cases have been identified so far, all of whom tested negative for COVID-19. However, air and surface in the workplace and residence of the patients came back with positive results. 

Tianjin's Hebei district has launched massive screenings in key areas. Some 130,000 residents have been tested and returned with negative results as of Thursday evening. 

The deputy head of the city's center for disease control and prevention recently noted that Tianjin had won a complete victory against the Omicron variant within 18 days since the latest COVID-19 spike raided the city, on January 8. He said that the current new local infections are all at the centralized quarantine sites and there is no risk of spreading the virus in communities since January 21.