BEIJING reported zero new coronavirus cases for the first time in 26 days, a sign the resurgence that ignited fears of a second wave in China looks to have been brought under control for now.

The city of more than 20 million people appears to have quelled a flare-up that infected 335 people, with infections down from 36 a day at their peak in mid-June. Authorities took a different approach to the virus when it reappeared in China’s political and economic hub after nearly two months of no locally transmitted cases than they did in Wuhan, the central city where the pathogen first emerged.

Instead of resorting to a sudden across-the-board lockdown that risked reversing the gains made since China started reopening, Beijing deployed more targeted measures. While some — like confining whole neighborhoods to their homes — may be more difficult to replicate in western democracies, they could hold lessons for other countries as they grapple with the inevitable return of the virus given an effective vaccine is months, potentially even years, away.

The Beijing resurgence, which took root in a wholesale food market in the city’s southwestern district, injected fresh uncertainty into the global struggle against the virus, hitting as citizens were getting used to a semblance of normal life. It served as a warning to places that look to have nailed the pandemic: the virus is elusive and isn’t easily beaten.

The outbreak, which seeded small virus skirmishes in other parts of China, was contained in less than four weeks. This is how they did it:

Hesitant to fully seal off Beijing like officials did in less economically important regions, the city relied on targeted testing at unprecedented speed.

Reminiscent of the mass operation conducted in Wuhan in May, when most of the population was tested for the virus in about two weeks, Beijing has tested more than 11 million people so far, according to Pang Xinghuo, deputy director of the Beijing Center for Disease Control and Prevention.

Overall, China has the capacity to test 3.8 million samples nationwide every day, officials said June 24, likely one of the fastest speeds worldwide.

Such scale is achieved using a method known as batch testing, where multiple samples are assessed simultaneously with detailed follow-up if any trace of the virus is found. Even without this method, Beijing can test over 300,000 people a day, six times more than the city’s capacity in March, according to Beijing Health Commission official Zhang Hua.

During the Beijing outbreak, entire groups were tested whenever an infection was found in their midst, including all the vendors at several major wet markets. All workers at a PepsiCo, Inc. food factory where a case was diagnosed had to undergo testing, and every delivery courier in the city — over 100,000 — was also sampled in weeks.

Rather than confining everyone in Beijing to their homes once the new outbreak emerged, authorities just locked down apartment blocks and housing compounds close to the epicenter. In these high-risk areas, only one member per household was allowed to leave to purchase necessities.

It’s an approach that other countries are also looking at, with authorities in the Australian city of Melbourne implementing localized lockdowns to quell a resurgence in cases there. Specific streets or neighborhoods would be told to stay home and practice social distancing, but the rest of the city would remain open. South Korea, too, has taken a targeted approach, shutting down businesses or schools where there have been outbreaks, but never imposing city-wide lockdowns.

Schools in Beijing were also closed again to limit commuting, while some entertainment venues were shuttered, too.

China appears to have drawn from the lessons of Wuhan’s devastating outbreak in January, when the virus was not well-understood by experts and the system unprepared for how contagious it is. Then, people swarming hospitals for help spread the virus to other patients and infected the environment.

This time in Beijing, residents were banned from entering hospitals unless they had tested negative for the virus, and makeshift test sites were set up in neighborhoods where cases were found to assist those showing symptoms.

Rather than seal off the city’s borders like in Wuhan — a move that caused widespread panic among residents, causing them to rush the city’s highways — China imposed quarantine requirements at destinations instead. People going from Beijing to some other provinces have to be isolated for two weeks in government-run facilities upon arrival, naturally discouraging travel. Carriers canceled flights, even though the airport remained open.

Despite what seems to be a relatively quick containment, the flare-up has shifted the contours of China’s fight against the virus. Prior to the Beijing outbreak, the nation appeared to be largely triumphant in its fight against a disease that continues to devastate the developing world, and China’s biggest rival, the US.

The cluster in the capital is believed to have started at the market, but its exact genesis and how it spread remains unknown.

After the virus was detected on a chopping board used for imported salmon at the market, a nationwide boycott of the seafood took place that affected exporting countries like Norway and Australia.

Experts say it’s more likely that the salmon was contaminated by an infected person, or by being in a dark, humid and low-temperature environment where the virus was present. China’s customs department tested over 47,000 samples of imported meat, seafood, vegetables and food and all were negative. Still, the country has suspended imports from some foreign meat plants, including a Tyson Foods, Inc. plant in the US where hundreds of employees tested positive for COVID-19 (coronavirus disease 2019), a move that potentially undermines its trade deal with Washington.

Amid that uncertainty — and as cases continue to pop up in areas around Beijing — China’s strategy is to remain circumspect. Even as infections taper, officials say that they won’t ease the restrictions until Beijing has seen two weeks without any new cases. — Bloomberg