Background Although international policy advocates opportunistic immunisation in every clinical setting it is not common practice. Inpatients have lower levels of cover against vaccine-preventable diseases (VPDs) than the community population.

Aims To evaluate secondary-care practice before and after introducing simple interventions to improve identification of under-immunised children and facilitate catch-up immunisations.

Methods The population-based child health database was used to check immunisation status for two cohorts of 200 consecutive admissions before and after routine printing of immunisation histories from the database and raising staff awareness. VPD susceptibility burdens were calculated for each child. Case notes were assessed for accuracy and documentation of ward-based interventions.

Results Fourteen per cent of all (400) children were under-immunised on admission and 27% of these were more than 5 years behind schedule. Under-immunised children’s VPD susceptibility burdens ranged from 0 – 40,858 days and in 59% exceeded 1,000 days. Over one month the paediatric admission unit saw children with a combined VPD susceptibility burden of 1,323 child-years. Positive identification of under-immunised children increased by 40% (95% CI; 12–62, p = 0.002) following the introduction of routine database printouts. This corresponded with a 20% increase in documented actions to encourage catch-up immunisation (95% CI; -1–27, p = 0.026). Catch-up immunisation rates remained low: 0% pre-discharge and 35% in the community at 5 months.

Conclusion Children presenting to British secondary care unit have large VPD susceptibility burdens. Positive identification of under-immunised children substantially improved following the introduction of routine database printouts but catch-up immunisation rates did not increase.