Retrospective cohort study exploring the impact of universal Tuberculosis (TB) vaccination cessation on the epidemiology of paediatric TB in Ireland, 2011–2021

•Significant decline found in cases born during universal vaccination.•Non-significant increase was seen in cases born after vaccination ceased.•BCG cessation has not yet directly impacted on 0–6 year olds in Ireland.•Interruption of previously declining trend may signal impending future increase. Since 2010, Ireland’s Tuberculosis (TB) crude incidence rate (CIR) remains below 10 per 100,000 population defining it as a low TB incidence country. Ireland maintained a universal BCG vaccination programme until its discontinuation in 2015 due to lack of vaccine supply. This study explores the impact of discontinuing a national universal BCG vaccination programme on the epidemiology of paediatric TB cases. We retrospectively analysed TB notifications aged 0–6 years old reported to the Irish National TB Surveillance System between 2011 and 2021. Key epidemiological characteristics and temporal trends in TB age specific incidence rates (ASIRs) were compared between 0 and 6 year old cases born during a period of universal BCG vaccination (2007–2015) and 0–6 year old cases born after BCG vaccination ceased (2015–2021). No significant temporal trend was detected in the overall 0–6 year old ASIR by notification year during 2011–2021 (IRR:0.95; 0.86–1.1). However, the temporal trend for cases born during universal vaccination showed a significant decline (0.74; CIR: 0.62–0.89) while cases born after BCG vaccination ceased had a non-significant increase (1.2; CIR: 0.73–1.86). A significantly declining temporal trend was detected among cases born in Ireland during universal vaccination (IRR:0.73; 0.62–0.86), but no significant trend was detected in the cases born outside Ireland during universal vaccination (IRR:0.83; 0.53–1.31). No significant trend was detected in cases born after vaccination ceased in either cases born in Ireland (IRR:1.0; 0.60–1.65) or those born outside Ireland (IRR:0.64; 0.29–1.40). Universal BCG cessation has not yet directly impacted on TB cases among 0–6 year olds in Ireland. However, interruption of the previously declining temporal trend in this cohort during universal vaccination may be an early warning of a future increase. Paediatric TB cases remain an important cohort for timely surveillance to monitor trends in this primarily unvaccinated cohort to evaluate the long-term effects.