Background: Since the beginning of 2014, there have been nearly 6,000 confirmed measles cases in northern Vietnam. Of these, more than 86% had neither been immunized nor was their vaccination status confirmed.

Objective: To establish the likelihood that children under five in Vietnam had ‘timely immunization completion’ (2000–2011) and identify factors that account for variations in timely immunization completion.

Design: Secondary data from the Multiple Indicator Cluster Survey (MICS), which sampled women aged 15–49 from the 1999 Vietnamese Population and Housing Census frame, were analyzed. Multilevel analysis using Poisson regression was undertaken.

Results: Proportions of children under five who had timely immunization completion were low, especially for HBV dose 2 and HBV dose 3, which decreased between 2000 and 2011. Among seven vaccines used in the National Expanded Program of Immunization (EPI) in 2000, 2006, and 2011, measles dose 1 had the highest timely immunization completion at 65.3%, 66.7%, and 73.6%, respectively, and hepatitis B dose 1 had the lowest at 17.5%, 19.3%, and 45.5%, respectively. Timely immunization completion was less common among children whose mothers had relatively less household wealth, were from ethnic minorities, lived in rural areas, and had less education. At the community level, the child’s region of residence was the main predictor of timely immunization completion, and the availability of hospital delivery and community prenatal care in the local community were also determinants.

Conclusion: The EPI should include ‘timely immunization completion’ as a quality indicator. There should also be greater focus and targeting in rural areas, and among women who have relatively low education, belong to minority groups, and have less household wealth. Further research on this topic using multilevel analysis is needed to better understand how these factors interact.