A section on the fringes of the Chinese city of Wuhan has been quarantined, marking the first time since 2020 that the district that reported the world's first COVID-19 lockout has enforced such a restriction, highlighting how far China is from normalcy following the pandemic.

Wuhan's Jiangxia district, home to over 1 million people, has been ordered to limit business activities and people remain indoors for the past two years in order to contain a strange pneumonia outbreak.

On Tuesday, following the discovery of four asymptomatic cases in the area, all public transportation was halted and entertainment venues were closed for three days.

While the limits are currently limited to a single district, the decision is likely to raise concerns about a potential expansion of curbs.

Since its initial lockdown in 2020 - which set a precedent for how Chinese authorities would handle outbreaks in other parts of the country - life in the pandemic-ravaged city of 11 million people had largely went back to normal, despite a small spread in April and a handful of infections in the past month.

China maintains its so-called "Zero COVID-19" lockdown strategy, limitations, and mass testing despite unprecedented challenges posed by contagious strains that defy the harshest restrictions. The nation reported 604 local cases on Tuesday, down from 868 the previous day.

Since July 19, Shenzhen, a manufacturing hub in the south of China, has reported four new cases, bringing the total to more than 150. The escalation caused some of China's largest corporations to operate under a "closed loop" system for seven days, increasing concerns about interruptions to the global supply chain.

Local officials requested that its 100 largest businesses, including iPhone manufacturer Foxconn and oil company CNOOC Ltd., limit activities to staff living within a closed loop or bubble, with minimal contact with people outside of their facilities.

The government also requested that non-manufacturing personnel have less contact with workplace floors in order to prevent infection.

Authorities in Shenzhen announced on Tuesday that the crisis is now under control, with the majority of cases having been discovered early and swiftly isolated; nevertheless, more infections are still expected.

Authorities have stated that they will rigorously implement the closed-loop system for drivers, who are prohibited from communicating with the outside environment while at work.

The outbreak is related to cross-border cases, according to Lin Hancheng, a health commission officer who declined to provide any specifics.