RESUMEN
Vaccines have contributed to reductions in morbidity and mortality from preventable diseases globally, but low demand for vaccination threatens to reverse these gains. Explorations of the determinants of vaccination uptake may rely on proxy variables to describe complex phenomena and construct models without reference to underlying theories of vaccine demand. This study aimed to use the results of a formative qualitative study (described elsewhere) to construct and test a model to explain the determinants of vaccination uptake. Using the results of a survey among more than 3,000 primary caregivers of young children in Nigeria, Uganda and Guinea, factor analysis produced six explanatory factors. We then estimated the effects of each of these factors on uptake of immunization using a structural equation model. The results showed that the probability that a child is fully vaccinated increases if a caregiver has support from others to vaccinate them (B = 0.33, ß = 0.21, p<0.001) and if caregivers had poor experiences with the healthcare system (B = 0.09, ß = 0.09, p = 0.007). Conversely, the probability of full vaccination decreases if the caregiver's husband exerts control over her decision-making ability (B = -0.29, ß = -0.20, p<0.001), or if the caregiver perceives vaccines to be of low importance (B = -0.37, ß = -0.27, p<0.001). Belief in religious protection (B = -0.07, ß = -0.05, p = 0.118) and a belief that vaccines are harmful (B = -0.12, ß = -0.04, p = 0.320) did not have an observed effect on vaccination status. This research suggests that interventions may benefit from that including entire families and communities in their design.