New Zealand beat the virus once. Can it do it again?

SYDNEY — As the week began, New Zealanders were celebrating 100 days without community spread of the coronavirus, drinking at pubs, packing stadiums and hugging friends.

Two days later, that suddenly changed: Four new cases, all related, emerged in Auckland. On Thursday, officials said the cluster had grown to 17, as they struggled to map out how the virus had returned to an isolated island nation championed for its pandemic response.

One theory is that it could have come through cargo. Some of the infected New Zealanders worked at a cold storage warehouse with imported food. Another focus is quarantine facilities for returning travelers, the source of an outbreak tearing through Melbourne, Australia.

A mystery and a few cases — that’s all it took for New Zealand to say goodbye to normalcy. Prime Minister Jacinda Ardern immediately announced a new lockdown for Auckland, a city of 1.7 million people, along with a huge testing, contact tracing and quarantine blitz that aims to quash COVID-19 for the second time.

“Going hard and early is still the best course of action,” Ardern said Thursday as she had relaunched her daily coronavirus news briefings. “We have a plan.”

Many other places have faced a similar challenge — Hong Kong, Australia and Vietnam have all confronted new waves after early triumphs. New Zealand, while disappointed by the abrupt resurgence, has reacted with an extraordinary level of urgency and action that it hopes will be a model for how to eliminate a burst of infection and rapidly get on with life.

“We were totally back to hugging, handshaking, restaurants, cinemas — all the stuff apart from going on holiday overseas,” said Siouxsie Wiles, a microbiologist at the University of Auckland. “What we’ve had time to do in the meantime is massively ramp up our testing and contact tracing, so this is going to be a real test of how quickly you can stamp it out again.”

“Everything about the time frame,” she added, “has been really compressed.”

Jeremy Hutton, 28, who works in finance and was out for a walk and a take-away coffee Thursday morning, asked what seemed to be on the minds of many: “Are we just going to keep doing this every couple of months?”

Ardern first heard about a potential positive case at 4 p.m. Tuesday while traveling in a van a few hours outside the capital, Wellington, after visiting a factory that makes face masks. At 9:15 p.m., she and Dr. Ashley Bloomfield, the director-general of health, appeared at a news conference where they announced the new cases — all four were from the same family; none had recently returned from overseas — and a lockdown that would start the following day.

“We have come too far to go backwards,” Ardern said. “Be strong and be kind.”

The lockdown was initially set for three days. Contact tracing had already begun.

Michael Baker, an epidemiologist who was a leading proponent of New Zealand’s forceful efforts to eliminate the virus during its initial outbreak months ago, said he heard about the new cases a few hours before the announcement. Like many others, he immediately started trying to work out what had gone wrong.

“The only way a virus can appear in the community in New Zealand is via the borders,” he said. “It’s been eliminated in New Zealand. There is really no chance it was persisting for the last three months without it being detected.”

But which border, how and when? No one yet knows.

Bloomfield said Thursday that those infected in the new cluster first showed symptoms around the end of July, suggesting that the virus had been in the community for at least a week before that. Genetic sequencing found similarities with versions of the virus in Britain and Australia.

To investigate the unproven idea of a spread through cargo, health officials have tested everyone at Americold, the cold storage company where some of the first cases appeared, with fast-tracked results identifying a total of seven workers with the virus. Scientists, aware of how the virus has thrived in cold storage at meatpacking plants in other countries, are also testing surfaces at the company’s two facilities.

If the virus is found to have moved through freight, the consequences could be significant for global trade. It could mean deep cleaning and lengthier wait times between shipment and delivery, along with more monitoring on ships and in ports.

But epidemiologists said such transmission was improbable: human-to-human contact was the most likely source.

“Ninety percent of cases occur in houses and workplaces,” Bloomfield said.

The cluster’s growth so far points to a path through kitchens and break rooms. One of the new infections reported Thursday involved a student related to a person identified Tuesday. Another seven are family members of Americold employees.

All of those newly infected will be placed in government quarantine facilities, in an escalation over containment measures during New Zealand’s first lockdown in March and April.

New Zealand has apparently learned what not to do from its neighbor and rival Australia, where 800 people who had tested positive in Melbourne were recently found not to be at home during random checks of self-isolation.

Australia’s missteps have also led New Zealand to focus on quarantine facilities — in Melbourne, the virus moved from travelers to hotel workers, who then carried it home.

Bloomfield said Thursday that workers at all 32 quarantine facilities that handle returning travelers would be tested for the virus this week, and once a week after that. Relatives of the workers may also be tested, along with every border official at New Zealand’s airports and other ports — between 6,000 and 7,000 federal employees.

“It will help us avoid any further and inadvertent spread into the community,” Bloomfield said.

The lockdown aims to do the same, and it’s being strongly enforced. In its first day and a half, authorities stopped 17,000 vehicles at 10 checkpoints. Most were traveling for the right reasons — for work, food or care-taking — and only 312 were turned back for trying to leave Auckland or other violations of the rules.

On Ponsonby Road, a high-end and normally busy shopping strip, the city seemed to be shifting quickly back into a form of partial hibernation.

Roscoe Thorby, 58, drank his to-go coffee in a deck chair he had set up on the sidewalk outside his regular cafe, just as he had done during the first lockdown.

But for some businesses, the sudden pivot from life as normal to near-total shutdown has been tough.

“It’s pretty devastating, after having a taste of what it is like to return to normality, getting the ball rolling and getting in the swing of things,” said Hugo Baird, 29, who owns a cafe, Honey Bones, and part of a restaurant called Lilian.

Serving to-go customers is financially feasible for the cafe, but not the restaurant. It has closed for this lockdown, however long it lasts, and the first casualty will be all the food that his staff had prepped for this week’s service, as well as opened bottles of wine and beer kegs.

“It is the uncertainty that kills business,” Baird said. He had finally gotten back to running at full capacity. “Now, going into another lockdown, although some people said it was inevitable, it does damage confidence.”

Still, despite the new cases, many New Zealanders recognized their enviable position. John Coop, 48, an architect, said he had recently spoken to a friend in London, and “there was a stark difference between his reality and what it is like here.”

“We’re incredibly grateful,” he added.

Baker, the epidemiologist, said that New Zealand’s prior success, and the sustained elimination of the virus in other places, such as Taiwan and Fiji, suggested room for optimism. He said the latest outbreak could be small and quickly brought under control.

“The government moved incredibly fast and decisively with the lockdown,” he said. “If there are any undetected chains of transmission, they will peter out.”

Thorby, sitting with his coffee, said he and many others were just hoping that what had worked once would work again, but more quickly. While his “heart dropped,” he said, when the news of the new cases hit, he supports the government’s aggressive response.

“I think we are sensible, and I think we trust the government,” he said. “We’ve had no reason not to trust our government.”

©2019 New York Times News Service