More than 8000 people in Germany have been returning to vaccination centre in Friesland for a repeat shot of Covid vaccine after a nurse admitted to replacing a vial of the Pfizer/BioNTech vaccines with saline solution and administering the doses to unsuspecting patients.

The 40-year-old nurse, who was in charge of preparing vaccine syringes in a laboratory, worked at the vaccination centre near Wilhelmshaven for seven weeks in March and April. Investigators later found the nurse had shared anti-vaccine and anti-lockdown posts on social media.

Heiger Scholz, who runs the Lower Saxony coronavirus task force, said in a press conference, “It is quite deceitful to sneak into a vaccination centre with the intention to do something like that.”

Regional broadcaster NDR says 8,557 people have been asked to go back for repeat vaccinations, and so far about 3,600 new appointments have been confirmed.

Police are not ruling out that a political motive could have prompted the nurse’s action, though her lawyers have rejected that and they also dispute the reported scale of the saline swap.

More witnesses are being questioned and so far no charges have been reported in the case.