Northern Ireland Health Minister Edwin Poots described Wednesday's major incident at Belfast's Royal Victoria Hospital as a "one-off" incident.
On the other hand, mutation can also occur as a one-off event at few individual sites.
"Last night's episode at the Emerson wasn't a one off," a friend of the actress told the website.
Lord Green, who left HSBC to become trade minister in 2011, will give evidence to the economic affairs committee at a one-off session on the culture of banking.
Secret Cinema has revealed that it showed Charlie Chaplin's The Great Dictator at a one-off secret screening on Sunday to protest against 'the attack on freedom of expression' represented by the Sony hacking.
Jason Donovan, Rick Astley, Bananarama, Sinitta and Dead or Alive are among those who'll perform at Hyde Park in a one-off concert on 11 July.
Intense negotiations are under way between political parties amid public anger at a one-off levy of up to 10% being imposed on savers.
Lewis performed "I Got You" for the first at a one-off private concert at the Hackney Empire in London, United Kingdom, on 2 November 2009, which served as a taster show to Lewis's The Labyrinth (2010).
Minogue performed at a one-off concert show held at entertainment venue Hammersmith Apollo, London, on 15 November 2003 to mark the release of the album.
Last month it was announced that several SAW acts will be appearing at a one-off show in London's Hyde Park this summer.
