The Ebola virus exploded in West Africa in 2014, causing the deaths of over 11,300 people. Sinead Walsh was there, serving as Ireland's ambassador to Sierra Leone, and she witnessed first-hand how the international humanitarian system operated, and failed to operate, under the toughest of circumstances.

Getting to Zero, the book Walsh has co-written with Oliver Johnson, a British doctor who ran an Ebola isolation unit in Freetown, the capital of Sierra Leone, is a powerful account of the struggle to bring the outbreak under control. She talked to Ruadhan Mac Cormaic for The Irish Times.