High Coverage, Hidden Inequities: Factors Associated With Incomplete Vaccination Among Orang Asli Children in Peninsular Malaysia

Childhood vaccination is a vital public health measure to prevent infectious diseases and reduce mortality among children under five. This study aimed to determine the prevalence of primary vaccination and identify factors associated with incomplete vaccination among Orang Asli children aged 12 to 59 months in Peninsular Malaysia. Data were derived from the 2022 Orang Asli Health Survey, a cross-sectional study using a complex multistage sampling design with structured questionnaires and verified immunization records. The overall prevalence of complete vaccination was 87.7%, with incomplete vaccination more common among younger children, those from the Negrito tribe, and those residing in urban and remote areas. Multivariable logistic regression showed that Negrito tribal affiliation (aOR = 3.31; 95% CI: [1.80, 6.09]) was associated with higher odds of incomplete vaccination, while older age was protective, reducing the odds with each additional month (aOR = 0.87; 95% CI: [0.84, 0.90]). The presence of respiratory symptoms was also protective, likely reflecting increased health care contact facilitating vaccination review (aOR = 0.02; 95% CI: [0.00, 0.28]). Targeted, culturally appropriate strategies, including engagement with tribal leaders and outreach, are essential to improve vaccination equity in these populations.