Staff at a mass vaccination centre in Cardiff have tested positive for COVID-19 amid a sharp rise in the infection rate in the city.
Cardiff and Vale University Health Board (CVUHB) did not confirm which centre was affected but said anyone identifying as a close contact would be made to isolate.
It comes as new testing sites are being opened around the city due to a surge in cases, with the infection rate having risen by 90% in the past week alone.
"We can confirm that a number of staff have tested positive at one of our Mass Vaccination Centres," CVUHB said in a tweet. "We are implementing testing of staff at the centre and anyone that is identified as a close contact will be asked to self-isolate.
"Currently, no additional risk has been identified to anyone who has been vaccinated at the centre. We would like to take this opportunity to remind the public that the virus is still prevalent in our local communities."
The Welsh capital's positivity rate (percentage of tests that are positive) of 18% shows it is "clear the virus is spreading through the community, making it extremely difficult to contain," Cardiff Council said.
There is currently a mass testing site located at Cardiff City Stadium and a local testing site in Museum Avenue.
More local test sites are opening this week - at Ely car park, the former Parkview Medical Centre, and Cardiff Bay County Hall car park.
Additional local test site locations could also become available in January.
Council leader Huw Thomas said residents should book a test if they are feeling unwell or displaying any COVID-19 symptoms, stressing "it has never been easier to get tested".
He added: "We are at a stage now where the rise in numbers is stark. If we don't follow the rules, our NHS and our services could be overrun by Christmas. The current predictions are dire.
"Hospital resources are being stretched and staff pushed to the limit following their experience at the sharp end of the pandemic."
There have been nearly 16,000 confirmed cases within CVUHB, Mr Thomas said, with 11 people currently in intensive care units and 278 medical and nursing staff unable to work because they are self-isolating.
