Accelerated by the emergence of BA.2 — a more-transmissible strain of the omicron variant — the virus has spread rapidly. Germany on Tuesday set a fresh record for infection rates for the four straight day. Austria has also reached new highs, while cases in the Netherlands have doubled since lifting curbs on Feb. 25.

Most authorities have shrugged off the surge, showing little appetite to re-impose curbs after easing measures just a few weeks ago. But the virus threatens to cause problems anyway, with businesses and schools disrupted as people call in sick.

“The messaging from politicians is encouraging many people who were taking precautions to mix with others,” said Martin McKee, professor of public health at the London School of Hygiene and Tropical Medicine. “It does seem very courageous, and indeed risky, to assume that the pandemic is over.”