As Covid-19 bacterial infections and fatalities in the European Union eclipse those in the U.S., the region is confronting an unpleasant actuality: Defeating the Delta variant is proving more durable than a virus-weary continent had hoped.

Rapidly-rising Covid-19 contagion in elements of Europe, like Germany, is sparking fears of another wintertime of whole hospitals. Nations around the world are speeding to roll out booster photographs as evidence accumulates that very last summer’s vaccinations are losing some of their efficacy.