Frequency and correlates of non-receipt of age-appropriate vaccination among children aged 6-35 months with medically attended diarrhea: Findings from the Enterics for Global Health (EFGH) Shigella study, 2022-2024

Complete childhood immunization protects children from long-term health complications and disabilities caused by vaccine-preventable diseases. Enterics for Global Health (EFGH)-Shigella surveillance was a two-year study measuring incidence rates and consequences of Shigella among children aged 6–35 months in seven sites located in Asia, Latin America and Africa. Here, we estimated the prevalence and factors associated with non-receipt of age-appropriate vaccination among children enrolled in the EFGH-Shigella study. In this nested cross-sectional study, we analysed data from 7,932 children aged 6–35 months presenting with medically attended diarrhea (MAD). Vaccines recommended per each country's national immunization schedule were extracted from medical records and risk factors were collected by caregiver interview and physical exam. We defined age-appropriate vaccines as receipt of the early childhood vaccinations within one month of the recommended age, according to the national immunization schedule, on the immunization card. Poison regression was used to identify independent factors associated with non-receipt of age-appropriate vaccination accounting for all covariates. Over half of enrolled children (51.7%) did not receive all age-appropriate vaccines most commonly in The Gambia (75.2%) and least frequently in Bangladesh (22.3%). Children 12–35 months of age were more likely not have all age appropriate vaccines compared to children 6–11 months (aPR: 1.47, 95%CI 1.39 to 1.54), children who came from households with ≥3 children aged <5 years (aPR:1.07;1.01-1.13), had mothers with low education (aPR:1.18; 1.12-1.24), and were wasted (Moderately: aPR: 1.06; 1.00-1.13; Severely: aPR: 1.13, 1.03-1.24) were more likely to miss all age-appropriate vaccines compared to their counterparts who did not. Non-receipt of age-appropriate vaccination was largely age dependent, driven by mother's education and severe wasting highlighting the need to design effective strategies that incorporate site complexities to improve timely vaccination targeting vulnerable groups.