text: Cardiff and Vale University Health Board confirmed it had shut the mental health wards to prevent further spread of the virus.
  The health board said a number of cases had been confirmed in the community, including in care homes.
  Dr Tom Porter urged anyone eligible to get a free flu vaccine to reduce risk.
  He said: "Every year flu causes thousands of deaths across the UK and vaccination is a quick and effective way of reducing your risk."
  The dominant strain circulating in the community is influenza A (H3), which particularly affects the elderly.
target: Three wards treating elderly patients have been closed at Llandough hospital in the Vale of Glamorgan after an outbreak of flu.