The Canterbury DHB is investigating after a person was injected with a used needle when getting a booster shot of the vaccine.
Vaccination Centre Sign Photo: RNZ / Angus Dreaver
A needle previously used to vaccinate one person was used for a second person's vaccination on Friday 10 December.
When staff realised they immediately advised the second person, and blood samples were subsequently taken from both people, the DHB said.
It had apologised to both people.
A comprehensive investigation into how the incident occurred was under way, DHB senior responsible officer for the Covid-19 response Dr Helen Skinner said in a statement.
The DHB was doing everything possible to support the vaccinator and the two people the needle was used on, Skinner said.
"We will continue to communicate with the person injected with a pre-used needle, supporting them and sharing any new information we receive.
"We would like to thank the staff involved for their quick actions, open communication with everyone affected and their cooperation in the current investigation into this issue.
"If there are improvements we can make to our systems to reduce the chance of this happening anywhere else, we will certainly be implementing them."