Care home workers have ended up in hospital after they were given five times the recommended dose of a Covid-19 vaccine.
On Sunday eight members of staff at a home in Stralsund in Germany's Vorpommern-Ruegen district were given the BioNTech-Pfizer vaccine.
Four were taken to hospital to be monitored after they developed flu like symptoms.
District chief Stefan Kerth said that the doses were given in error.
"I deeply regret the incident," he said.
"This individual case is due to individual errors.
"I hope that all those affected do not experience any serious side-effects."
BioNtech has previously said that larger doses were tested in the Phase 1 study without serious consequences.
In the days before Christmas the European Medicines Agency approved the BioNTech-Pfizer jab for use across the EU.
The rollout in Germany has encountered another problem in the week since.
Some of the country's districts decided not to use vaccines received over the weekend on suspicion that cold conditions were interrupted during delivery.
The vaccine must be stored at very low temperatures of about -70C, before being transported to distribution centres in cool boxes filled with dry ice.
Once out of ultra-low temperature storage, the vaccine must be kept at 2C to 8C to remain effective for up to five days.
Temperature trackers showed that thousands of the vaccines may not have been kept cold enough during transit.
Pfizer was contacted for comment.
