Impact of COVID-19 pandemic on childhood immunization coverage in Indonesia: lesson learned from a nationwide analysis of the Expanded Programme on Immunization

Background: The COVID-19 pandemic disrupted childhood immunization programmes in many countries worldwide. However, evidence on its impact in low and middle-income countries remains limited. This study examined the impact of the COVID-19 pandemic on childhood immunization coverage across 514 districts in Indonesia and identified district-level associated factors. Methods: We conducted a nationwide longitudinal analysis of the Expanded Programme on Immunization to compare immunization coverage before and after the pandemic. The outcome variable was the annual childhood immunization coverage (proportion of children aged 0-12 months who have received all recommended doses of childhood immunization as per the national immunization schedule). The explanatory variables include COVID-19 burden and vaccination rates, health system and human development indicators. Mixed-effect logistic regression was done to assess association between the explanatory and outcome variables. Results: At the national level, the coverage was 83.2% in pre-pandemic, 75.0% in the first year of pandemic, and 88.6%, in the second. In the first year, 69.3% of districts experienced significant decline, with a lower national coverage ratio of 0.92 (95% confidence interval 0.89-0.94). In the second year, 36.2% districts were still affected. The multivariable analysis showed that a significant decline in coverage during the first pandemic year was associated with high COVID-19 incidence (adjusted odds ratio 2.19, 95%CI 1.01-4.73 for the highest vs. lowest group), low midwife adequacy (5.84, 2.40-14.16 for the lowest vs. the highest group, 2.61, 1.26-5.40 for low-middle vs. the highest group), and a high proportion of health facility-based births (2.98, 1.49-5.98 for middle-high vs. the lowest group). Conclusions: The COVID-19 pandemic negatively and unevenly impacted childhood immunization in Indonesia, with greatest impacts in districts facing a higher COVID-19 burden and weaker health system capacity. These findings underscore the need for targeted efforts to strengthen the local health system for future health crises. Keywords: COVID-19, pandemic, immunization, vaccine preventable diseases