Health and social care will in future be planned and delivered in six regions across the country, it was confirmed on Wednesday.
Under the Government plans, the new health regions will have greater autonomy to make decisions at a local level.
As part of the re-form Donegal, Leitrim, Sligo, Galway, Roscommon and Mayo will be known as Area F, phasing out what was previously known as CHO 1.
Mr Harris said the new regional structure was key for the delivery of the Slaintecare reform programme.
“This will result in clear financial and performance accountability, empower frontline staff and devolve authority from the HSE to local regions.”
The Department of Health said the current operation of the HSE would continue “while a process of collaborative design” of the new regions took place over the coming months.