Festooned with hibiscus flowers and woven palm fronds, scores of guests gathered for a celebration during New Caledonia’s wedding season. The aroma of grilled fish and yams bathed in coconut milk wafted over the revelers on the island of Lifou, population 10,000.

The celebration on the atoll in late August seemed safe. For a year and a half, New Caledonia, a French territory in the South Pacific, had escaped the coronavirus pandemic. Quarantines and border controls kept the virus out, just like they had done during the worst of the influenza pandemic a century earlier.

But by mid-September, the delta variant was racing across New Caledonia, home to about 270,000 people. Of the nearly 13,300 people who tested positive within the span of a few weeks, more than 280 people died, a higher mortality rate than what the United States or France experienced last year.