When Fortune magazine recently published its annual ranking of the world’s 50 greatest leaders, New Zealand’s Prime Minister Jacinda Ardern topped the list. The editors lavished praise on Ardern’s handling of the COVID-19 pandemic, hailing the way she “targeted not just suppression of the virus, but its complete elimination.” Fortune deemed her strategy a success: Only 26 people had died of the disease in New Zealand, which imposed the first of several aggressive nationwide lockdowns 17 months ago and closed off the country’s borders to all non-citizens and non-residents.

Ardern’s leadership is no longer looking quite so brilliant. On Aug. 17, after a single COVID infection was reported in New Zealand, the prime minister again ordered the entire country to close. Under the so-called Level 4 restrictions, all Kiwis must stay at home except for food or medication, or to exercise alone. Bars, restaurants, gyms, theaters, swimming pools, museums, libraries, and playgrounds are all shuttered. So are schools and daycare facilities. Weddings and funerals are banned.

“Do not congregate. Don’t talk to your neighbors. Please keep to your bubbles,” Ardern told the nation. “The delta variant … can be spread by people simply walking past one another, so keep those movements outside to a bare minimum.” The latest lockdown is to remain in force at least through midnight Friday, but may be extended on the prime minister’s say-so. Meanwhile, as of Monday, nearly 150 infections had been reported since the appearance of that single case last week.

“Here we are back in the world’s strictest lockdown,” journalist Andrea Vance wrote in Stuff, a top New Zealand news site. “The rest of the world is embracing its post-pandemic future while New Zealand enters a March 2020 time warp.”

It turns out that a strategy to achieve “complete elimination” of the coronavirus is a strategy for failure. During last year’s heated debates in the West over the wisdom of trying to control the pandemic by bringing economic life to a near-halt, lockdown supporters praised Ardern fulsomely for having so forcefully “squashed” the virus. New Zealand’s ultra-low rate of infection and death was seen as proof that strict lockdowns were indeed the best way to defeat the disease.

But they weren’t. Dozens of academic studies have concluded that lockdown decrees were largely futile in preventing the virus from spreading, and accomplished little that could not have been achieved through less restrictive means. The trajectory of the pandemic since early 2020 has made it clear that, as the New York Times put it in a recent headline, “Covid Isn’t Going Away.” So across the United States, even as the highly contagious Delta variant causes hospitalizations to surge, governors and mayors have not reverted to last year’s approach of pulling the plug on the economy.

“Most of the country remains fully open,” reported the Times, “and … most officials have so far steered away from restricting or shuttering businesses.” The Centers for Disease Control and Prevention is recommending that Americans with compromised immune systems, those who remain unvaccinated, and some others continue to wear masks, but has not called for shutting down businesses.

The key difference this time around, of course, is that most Americans, like residents of most advanced democracies, are vaccinated. Nearly 61 percent of the US population has been given at least one dose, and 51.5 percent has been fully vaccinated, according to Bloomberg’s Covid-19 Vaccine Tracker. Across the European Union, the fully-vaccinated level is nearly 57 percent. In Israel, it’s 60 percent. In Britain, 63 percent. In Canada, 65 percent.

But in New Zealand, barely 19 percent of the population — less than 1 in 5 — has been fully vaccinated. Just one-third of New Zealanders have gotten even a single dose. In no developed nation have vaccinations lagged so badly.

New Zealand is back in a “March 2020 time warp” because its focus for the past year and a half was not on getting the virus under control but on the chimera of eliminating it entirely. Bamboozled, perhaps, by all the flattery she was getting, Ardern persisted in what she called a “Stamp it Out” approach. More than once she declared that New Zealand had defeated COVID.

Only now, at long last, is the government making it a priority to get the vaccine into as many people as possible. Only now has it sunk in that the virus can’t be wiped out for good — not even an island nation like New Zealand can wall itself off from the pandemic. The way out of the COVID nightmare is through vaccinations, not through nationwide closures and sealed borders. Americans and Europeans have put 2020 lockdowns behind them. It’s time New Zealand followed suit.

(Jeff Jacoby is a columnist for The Boston Globe).