TAIPEI (Taiwan News) — Northeastern China's Liaoning Province is experiencing a new coronavirus outbreak and its efforts to contain it has been complicated by super spreader events and an unusually long incubation period.

Tang Yi (湯易), head of the Civil Affairs Bureau of the Liaoning port city of Dalian, warned on Monday (Jan. 4) that the surge is characterized by a longer incubation period, higher transmissibility, and other factors, which is impeding efforts to rein in the spread of the disease, according to the state-run China News Service.

In one case, a patient did not test positive until the 11th nucleic acid test, indicating a greater difficulty of identifying potential COVID-19 carriers. This means a 14-day quarantine is insufficient, and the city has added seven days to quarantines to curb the outbreak, Tang added.

Not only has Dalian ratcheted up quarantine and testing measures, but it has also scrambled to check the emergence of super spreaders. As of Sunday (Jan. 3), one confirmed case had infected at least 33 people at a family gathering and through contact with neighbors, according to Zhao Lian (趙連), deputy director of the Dalian Health Commission.

Also seeing a rise in superspreaders is Shenyang, another major city in Liaoning, which has joined Dalian in adopting a “wartime mode” to deal with the threat of the virus. Mass testing is being conducted, and most businesses have closed as officials fear pandemic control could be set back by the upcoming Lunar New Year holiday, when the country experiences one of the largest human migration events of the year.