He had cystic fibrosis (CF), an inherited condition that causes sticky mucus to build up in the lungs and digestive system.
O'Hagan family Cahir, with his sister Ciara, brother Paul, father Kevin and mother Briege'One in a million'There are more than 500 people living with cystic fibrosis in Northern Ireland.
The then-health minister, Robin Swann, said Kaftrio would give those living with cystic fibrosis a "better quality of life".
But they do not work for everyone with cystic fibrosis.
According to the Cystic Fibrosis Trust, about 90% of the UK CF population have mutations that will ultimately be eligible for these drugs.

Cystic Fibrosis: 'The fight of the CF community goes on'