Due to widespread use of diphtheria vaccine since the 1930s the incidence of diphtheria has decreased markedly since the 1940s. In 1948 (first year for which data are available) over 500 diphtheria cases and 30 deaths were reported. The number of cases declined rapidly over the subsequent years and by the 1960s relatively few cases were reported each year.
One diphtheria case (C. ulcerans) was notified in Ireland in 2016 and one in 2015. The last diphtheria case (and death) notified prior to this was in 1967.