SUMMER BECKONS, and the coronavirus pandemic is still running strong in the United States. Fortunately, there is more clarity now about how to fight it than in the terrible early weeks. A devastating second wave is possible — but can be averted.

All available evidence points in one direction — that people and governments should be as relentless as the virus. Wear masks; wash hands; avoid crowded, confined spaces; and set up adequate testing and contact tracing.

This appears to be helping improve the situation in Europe. In hard-hit Italy and across much of the continent, countries have restarted their economies and resumed socializing to some extent without experiencing the dire consequences of a second wave. The Post’s correspondents report that virologists have become more optimistic that, even absent a vaccine or drug therapy, Europe can manage the pandemic at least through the summer with nothing more than localized and containable hot spots. Europeans are hand-washing and mask-wearing, and it helps. Also, Europe’s opening is still gradual, with a ban on large events; international flights and tourism have been on hold, while some countries have not restarted schools. And Europe also shows what can go wrong. Closed environments can become incubators for disease. Poland reacted quickly to the pandemic and thus didn’t suffer a nationwide toll like Spain or Italy, but now the coal mines of Silesia are the scene of a continuing outbreak and thousands of infections.

In the United States, New York City, an early epicenter, is taking the first steps toward reopening, and a decline in the New York region is a welcome sign after so many weeks of sickness and death. Another positive sign is that intensive care unit capacity in the United States is not overstretched, as had been feared. But the nation is not beyond danger. A host of states are seeing a jump in new cases, including California, Arizona, Utah, Texas, North Carolina, Michigan, Florida and Arkansas. In Houston, which initially saw a decline, the case count has swung sharply upward in recent days, almost to levels of mid-April. In South Carolina, cases on Saturday reached the highest count for a day since the pandemic began.

These worrisome signs suggest that some places should neither ease up on physical distancing nor return to business as usual. Also concerning is whether the protests over police brutality might have seeded outbreaks that will appear two weeks or so from now.

Ultimately, the battle against the coronavirus depends on choices we make. For individuals, this means a commitment to wearing face masks, washing hands and avoiding crowded enclosures. For states and cities — delegated the task by an irresponsible president who turned his back on it — the key is building a robust testing, contact tracing and isolating regimen as soon as possible. So far, the record is quite uneven. This won’t be a carefree summer, but all the effort is worth it if a second wave can be avoided or ameliorated.

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