The Department of Health on Wednesday said it's investigating an incident in which 14 people were given out-of-date bivalent vaccines at a medical centre in Kowloon Bay.

The department said it found that the centre, run by Quality HealthCare, had in the past week used BioNTech bivalent vaccines that had been kept one to eight days after the suggested use-by date.

No one has reported feeling unwell.

Health officials said they are highly concerned about the case, adding that an investigation has been launched to find out whether the centre has violated any guidelines.

The department said it reminded the centre to check the suggested use-by dates of vaccines regularly to prevent a repeat of the incident.