Backgrounds:

Vaccination reduces infectious diseases burden, the leading cause of under-five mortality, occurring mainly in low- and middle-income countries (LMICs). The latest Global Vaccine Action Plan has set a target of 90% immunisation coverage for all vaccines included in national programmes by 2020.

We aimed to estimate immunisation coverage among children in Madagascar, Cambodia, and Senegal and to identify determinants associated with incomplete immunisation.

Methods

We used data from a child cohort (BIRDY cohort, 2012-2018) conducted both in urban and rural areas of these 3 countries. Children were followed-up from birth up to the age of 24 months with at least one home visit monthly. Immunizations received since the last visit were collected after verification in the child's vaccination card. Risk factor analysis was performed with logistic regression models.

Results:

Among the 3606 children followed-up, all vaccine coverages were below the 90% threshold, except for BCG vaccine coverage in Cambodia. They were higher for vaccines recommended at birth and a decrease in coverage with age was observed for vaccines requiring several doses in all countries. For example, the decrease in coverage between the first and the third dose of pentavalent vaccine ranged from 20% to 40% (p<0.001).

Low birth weight (<2500g) was an important risk factor for non-vaccination for vaccines recommended at birth (BCG and oral polio vaccine) in all three countries (aOR ranging from 1.93 [1.11-3.38] to 4.28 [1.85-9.37]). Also, high maternal education (from 0.38 [0.24-0.60] to 0.61 [0.38-0.97]) and high antenatal care attendance (from 0.39 [0.25-0.63] to 0.66 [0.52-0.84]) were identified as protective factors.

Conclusions/Learning Points:

Vaccination coverage is still low in these countries. A multi-disciplinary approach is needed to improve coverage and thus reduce the burden of vaccine-preventable infectious diseases in LMICs.