Shanghai launched another five-day citywide mass testing campaign on Friday as part of efforts to achieve zero-transmission within communities as quickly as possible.

The city has reached the critical stage of achieving zero community transmission, said local authorities in announcement published on Shanghai Fabu, the municipal government's WeChat account, on Friday.

Early detection remains essential to the dynamic zero-COVID strategy, which relies on speed and accuracy to stem the transmission of the virus, according to the announcement.

Mass testing for communities, which includes both nucleic acid and antigen tests, will continue across the city based on their level of exposure risk to the virus.

While residents in lockdown zones, namely neighborhoods that have reported infections over the past week, will undergo nucleic acid tests daily, those in controlled zones will take three antigen and two nucleic acid tests. Residents in precautionary zones with no report of infections over the past week will take four antigen tests and one nucleic acid test.

Authorities also called on neighborhoods to strengthen prevention and control measures at this critical stage based on their exposure risks.

Related medical research and and vaccination rates should be improved as well, according to the announcement.

Shanghai reported 1,931 new confirmed cases and 15,698 asymptomatic infections on Thursday.