Does introducing an immunization package of services for migrant children improve the coverage, service quality and understanding? An evidence from an intervention study among 1548 migrant children in eastern China

BACKGROUND An EPI (Expanded Program on Immunization) intervention package was implemented from October 2011 to May 2014 among migrant children in Yiwu, east China. This study aimed to evaluate its impacts on vaccination coverage, maternal understanding of EPI and the local immunization service performance. METHODS A pre- and post-test design was used. The EPI intervention package included: (1) extending the EPI service time and increasing the frequency of vaccination service; (2) training program for vaccinators; (3) developing a screening tool to identify vaccination demands among migrant clinic attendants; (4) Social mobilization for immunization. Data were obtained from random sampling investigations, vaccination service statistics and qualitative interviews with vaccinators and mothers of migrant children. The analysis of quantitative data was based on a "before and after" evaluation and qualitative data were analyzed using content analysis. RESULTS The immunization registration (records kept by immunization clinics) rate increased from 87.4 to 91.9% (P = 0.016) after implementation of the EPI intervention package and the EPI card holding (EPI card kept by caregivers) rate increased from 90.9 to 95.6% (P = 0.003). The coverage of fully immunized increased from 71.5 to 88.6% for migrant children aged 1-4 years (P < 0.001) and increased from 42.2 to 80.5% for migrant children aged 2-4 years (P < 0.001). The correct response rates on valid doses and management of adverse events among vaccinators were over 90% after training. The correct response rates on immunization among mothers of migrant children were 86.8-99.3% after interventions. CONCLUSION Our study showed a substantial improvement in vaccination coverage among migrant children in Yiwu after implementation of the EPI intervention package. Further studies are needed to evaluate the cost-effectiveness of the interventions, to identify individual interventions that make the biggest contribution to coverage, and to examine the sustainability of the interventions within the existing vaccination service delivery system in a larger scale settings or in a longer term.