In Germany's most populous state of North Rhine-Westphalia, the regional government said there had been a spike in cases at a slaughterhouse in the district of Coesfeld, where over 150 of the 1,200 employees tested positive for the virus.
Local officials said the outbreak meant the district would be forced to postpone by one week the planned May 11 reopening of restaurants, tourist spots, fitness studios and larger shops, while residents would have to continue limiting their social contacts.
The step-by-step reopening of schools and daycare centres will go ahead as scheduled.
It marks the first setback since Merkel on Wednesday announced that Germany's slowing infection rate and relatively low mortality rate meant the country had weathered the “first phase of the pandemic” and could cautiously return to normal.
The decisions on relaxing restrictions are in the hands of Germany's 16 federal states however, who have agreed to reimpose curbs if the number of new cases hits 50 per 100,000 people over seven days.
North Rhine-Westphalia's health minister Karl-Josef Laumann said the barrier had been breached in Coesfeld, where the slaughterhouse cluster pushed the infection rate up to “61 per 100,000 residents”.
He ordered the temporary closure of the slaughterhouse and said employees at all of the state's meat processing plants would now undergo testing for the novel coronavirus. In the northern state of Schleswig-Holstein, an outbreak also at a slaughterhouse pushed the district of Steinburg over the infection threshold.
It was not immediately clear what action the authorities would take and whether they would pull what German media have dubbed “the emergency brake”.
In the eastern state of Thuringia, the district of Greiz recorded more than 80 infections per 100,000 people over the past week, mainly among residents and employees of six care homes and a geriatrics hospital.
The Thuringia government plans to hold crisis talks early next week on how to proceed with the planned loosening of the stay-at-home measures in the hotspot.
“To be clear: we're not going to put the entire district in quarantine,” said Martina Schweinsburg, the chief administrator in the district of Greiz, stressing that just two small towns were particularly affected.
Germany has so far recorded 167,300 coronavirus cases nationwide and 7,266 deaths, the Robert Koch Institute for public health said Friday.