TIANJIN — North China's Tianjin, a municipality that neighbors Beijing, has decided to start a citywide nucleic acid testing after 20 people tested positive for COVID-19, authorities said on Jan 9.

The infections were reported from 6 pm on Jan 7 to 9 pm on Jan 8 in Jinnan district, and the gene sequencing found the first two locally transmitted confirmed cases were infected with the VOC/Omicron variant, according to the municipal headquarters for COVID-19 prevention and control.

The other 18 infections are mainly students and their family members related to a daycare center and a primary school where the first two cases were from, Gu Qing, director of the municipal health commission, said at a press conference late Jan 8.

The virus has spread for at least three generations in the latest resurgence, and more cases may emerge, said Zhang Ying, deputy director of the city's center for disease control and prevention.

It is not confirmed yet whether the infections are related to the imported case of Omicron variant infection in the city.

The citywide nucleic acid testing is expected to be completed in 24 hours in four districts from 7 am on Jan 9 and in 12 other districts from 7 am on Jan 10, and residents will not be given a green health code until receiving a negative test result, the headquarters said.