Shanghai's biggest international airport momentarily descended into chaos Sunday night, after authorities ordered a mass testing drive-in response to a small outbreak of COVID-19 linked to several cargo handlers.

Since the beginning of November, seven cargo workers and their close contacts at the Shanghai Pudong International Airport have been diagnosed as confirmed coronavirus cases, including two reported on Sunday.

In a bid to contain the cluster, authorities ordered all cargo staff at the airport to undergo coronavirus tests overnight and set up a temporary testing site on the second floor of a parking garage, according to a statement from the Shanghai government.

Photos and videos circulating on Chinese social media show hundreds of people packed closely together inside the garage -- the opposite of social distancing -- with a line of people in hazmat suits trying to hold back crowds pushing forward.

But the chaos appeared to have calmed before midnight, when the airport police posted photos on Weibo showing workers lining up orderly for the tests.

As of Monday morning, 17,719 samples had been collected. Of the 11,544 samples that have been tested, all received negative results, officials said at a news conference.

While the initial chaos has drawn criticism on Chinese social media, the swift, drastic response over just a few cases highlights the length the Chinese government is willing to go to in order to stamp out any resurgence of the virus.

China's zero-tolerance approach is in stark contrast to the United States, which is struggling to cope with its largest wave of infections since the pandemic began. Contact tracing seems almost impossible, with daily new cases above 100,000 for three straight weeks.

On Saturday, the US caseload surpassed 12 million -- an increase of more than 1 million cases in less than a week. On the same day, U.S. President Donald Trump skipped a special side-conference focused on the pandemic during his final Group of 20 summit.

Trump was spotted at his golf course outside of Washington, DC, while world leaders including French President Emmanuel Macron, German Chancellor Angela Merkel, and South Korean President Moon Jae-in discussed global responses to the virus and how to improve pandemic preparedness.

ZERO-TOLERANCE APPROACH

In China, several cities have reported new coronavirus cases over the past week -- and all have been met with immediate action from authorities, from extensive testing and contact tracing to partial lockdowns.

In the port city of Tianjin, some 600 miles (965 kilometers) from Shanghai, authorities are testing 2.6 million residents in one district after reporting five locally transmitted cases on Friday, the Tianjin Health Commission said in a statement.

The mass testing, which started on Saturday, will cover all residents living in the Binhai New Area district, and is expected to be completed in three days.

As of Sunday evening, Tianjin has received more than 2.25 million test samples, of which over 1 million have come back negative, the health commission said.

The more targeted approach -- focusing on one district instead of the entire city of 15 million people -- differs from the city-wide testing drives adopted by large cities such as Wuhan and Qingdao during earlier local outbreaks.

Smaller cities, however, appear intent on testing every resident. Manzhouli, a major land port on the Chinese border with Russia, announced plans to test the whole city in three days after two local infections were reported Saturday. According to the Global Times, a state-run tabloid, a total of 300,000 residents will be tested.

Manzhouli's main train station has suspended operations, while its airport has halted all transfer flights to the regional capital of Hohhot. Schools are suspended, mass gatherings are banned, and non-essential businesses are closed, according to the city government.

While these measures have become a standard response to new outbreaks in China, other governments have so far appeared reluctant to introduce similar measures.

In Hong Kong, the local government tried to roll out city-wide testing for its 7 million residents during its third wave of infections in September. In the end, only 1.7 million people showed up for the two-week testing drive.

As the city faces another surge in coronavirus cases, Health Secretary Sophia Chan said on Sunday the government will give a HK$5,000 ($645) handout to anyone in the city who tests positive to encourage people to undergo testing.

SECOND WAVE

As the winter approaches, countries in Asia have also faced a second wave of coronavirus. While most will be unlikely to adopt China's zero-tolerance approach, many have tightened restrictions to slow its spread.

In Japan, daily coronavirus cases have surpassed 2,000 for five days in a row. Amid surging cases, the country's Prime Minster Yoshihide Suga announced last week that the government's travel and dining promotion program will be halted in coronavirus hotspots to curb further infections.

On Monday, South Korea declared an "emergency period" in the capital city of Seoul until the end of the year, due to a spike in Covid-19 cases, according to the city's acting mayor Seo Jung-hyup.

Under the announcement, public transportation will reduce capacity by 20% after 10 p.m. and gatherings of more than 10 people will be banned. The city will also conduct regular coronavirus tests on some 40,000 workers and users of nursing hospitals and daycare centers.

The measures come after a series of new restrictions were announced for Seoul on Sunday, including mandatory mask wearing indoors and closures of entertainment facilities such as clubs. Restaurants are only allowed to do deliveries and takeout after 9 p.m., gatherings will be limited to 100 people, and schools must operate at one-third capacity.