Elderly people were left queueing in the cold for hours due to an IT failure that brought Cardiff's mass vaccination centre to a halt.
Cardiff and Vale University Health Board said that a "national IT outage" was causing problems at their mass vaccination centres.
It came as temperatures across the area dipped below zero with snow forecast for large parts of the country.
At around 9.40am on Thursday the health board said: "Due to a national IT outage we are experiencing problems with the systems at our Mass Vaccination Centres which is unfortunately resulting in queues as we process our patients.
"We are trying to get people through as quickly as possible so please bear with us."
The problem was only resolved at around 11.30am.
Katherine Cousins said: "I'm early anyway so the big queue isn't problem. I'm just looking forward to getting it."
The health board has been contacted for further information.
