SINGAPORE, Sept 20 — Two adults were given an undiluted vial of the Pfizer-BioNTech vaccines each on Sept 15, with one needing hospitalisation after experiencing headache and increased heart rate, the Ministry of Health (MOH) said.

In response to queries from TODAY, the ministry said that it was alerted on Sept 19 to the incident. It happened at a clinic of ProHealth Medical Group in Hougang on Sept 15.

“One was hospitalised after experiencing headache and increased heart rate, and has since been discharged,” MOH said, adding the other patient did not report any adverse reaction.

Each vial of Pfizer-BioNtech vaccine reportedly supplements five doses. This is based on an incident last year when an employee at the Singapore National Eye Centre was wrongly administered the equivalent of five doses of the Pfizer-BioNTech Covid-19 vaccine due to a human error.

“MOH takes a serious view of this incident and is carrying out a thorough investigation,” the ministry said.

“The clinic and doctor who administered the vaccine have been suspended from the national vaccination programme until further notice.”

TODAY has asked MOH when the patient was hospitalised. ProHealth Medical Group declined to comment.

In a separate incident earlier this year, MOH said it was investigating the death of a 103-year-old nursing home resident who was wrongly given a fourth dose of a Covid-19 vaccine in a case of “mistaken identity”.

She had died on Jan 10, and an autopsy ordered by a coroner found the main cause of the woman’s death was pneumonia, with other contributing factors being cerebral infarction (or stroke) and coronary artery disease, which are natural disease processes common in seniors, MOH added at the time. — TODAY