SINGAPORE - A total of 117 patients and staff at a Bukit Merah polyclinic were given wrong doses of their Covid-19 vaccine, with only one-tenth of the recommended dosage, between Wednesday (Oct 20) and Friday.

SingHealth Polyclinics said in a statement on Sunday that there had been an error in identifying the markings on new syringes that were recently introduced in the clinic.

Six staff and 111 patients who were taking the Pfizer BioNTech / Comirnaty vaccine were affected. As a result, the affected patients received a much lower dose of about 10 per cent of the recommended dosage, it said.

The error was detected on Friday when a colleague helped with the vaccinations, said SingHealth Polyclinics.

Its investigations confirmed that the incident was isolated, and all other vaccinations and services at its polyclinics were not affected, the statement added.

SingHealth Polyclinics chief executive officer Adrian Ee apologised for the anxiety and inconvenience caused to all affected patients and their family members.

He added that the group will take all the necessary steps to address their concerns as well as arrange for Covid-19 replacement vaccinations as soon as possible.

Said Dr Ee: "We have taken immediate steps to rectify the error, and staff have been reminded on the proper use of the new syringe to administer the Covid-19 vaccine.

"We would also like to reassure our patients that we have thoroughly reviewed our processes, and will ensure that staff are familiar with the use of new devices."

Following the detection of the incident, immediate action was taken to determine the extent of the error and reach out to the affected patients as soon as possible, said SingHealth Polyclinics.

The group added that, based on current vaccination guidelines by the Health Ministry, patients with the initial reduced dose are unlikely to experience adverse reactions.

It is clinically safe for them to proceed with the Covid-19 vaccine replacement dose.

As an added precaution, all affected patients will be assessed by a doctor before they receive their replacement dose at the polyclinics.

Earlier this year in January, a staff member at the Singapore National Eye Centre was mistakenly given the equivalent of five doses of the Pfizer-BioNTech Covid-19 vaccine.

The worker in charge of diluting the vaccine had been called away to attend to other matters before it was done.

A second staff member had then mistaken the undiluted dose in the vial to be ready for administering.

In June, a 16-year-old boy was wrongly given the first dose of the Moderna Covid-19 vaccine, which has not been approved for those under age 18 in Singapore.

The mistake was discovered at Kolam Ayer Community Club vaccination centre when its staff identified that the boy was under 18 years of age after he had been given the shot.