Portugal’s feat has turned the country into a cutting-edge pandemic laboratory — a place where otherwise-hypothetical questions about the coronavirus endgame can begin to play out. Chief among them is how fully a nation can bring the virus under control when vaccination rates are about as high as they can go.

The emerging answer is promising — mostly. In Portugal, every indicator of pandemic severity is quickly trending downward. The death rate is half the European Union average and nine times below that of the United States…

But Portugal’s experience is also providing a note of caution: a reminder that 1½ years into this pandemic, the current tools of science still might not be enough. The virus is still causing cancellations, lost work days and sickness — in rare cases severe. It spreads less quickly and less far than it would in places with lower vaccination rates — which benefits everyone, including the 12-and-under children not yet eligible for shots. But herd immunity remains elusive. Daily calculations about risk remain, even without large ranks of unvaccinated people to blame.

“We have achieved a good result, but it’s not the solution or miracle one would think,” Portugal’s health minister, Marta Temido, said in an interview.