Rates of acute mental health presentations in youth were increasing pre-pandemic internationally. Longitudinal studies following COVID-19 attest to ongoing deterioration in youth mental health, recognising adverse unintended consequences following public health restrictions.

To examine whether the initial post-COVID-19 increase in mental health presentations persisted following the reclassification of COVID-19 to endemic status, accompanied by the removal of most restrictions.

All referrals to paediatric liaison psychiatry (PLP) between January 2018 and December 2022 in a Dublin tertiary children's hospital were included in the study. An interrupted time series analysis with autoregressive integrated moving average models was conducted, examining referrals with respect to different phases of COVID-19 and application of public health restrictions.

Some 1385 referrals to PLP were received over the 5-year study. There was a significant decrease in PLP referrals immediately post-COVID-19, followed by a significant and sustained increase as the pandemic progressed and moved to endemic status. Public health restriction phases had a unique effect on those presenting with suicidal ideation, with a significant increase in the number of referrals. There was no effect of restrictions on other clinical profiles.

Increased referrals for youth with mental health difficulties, reported during the COVID-19 pandemic, persisted into the early endemic stage, after COVID-19 public health restrictions ceased. Specific impacts of restrictions on suicidal ideation referrals require further study. Investment in child and adolescent mental health services remains a priority, and future pandemic response strategies need to examine unintended consequences of any enforced public health measure.