Factors Associated with Vaccination Uptake among Young Children: A Follow-Up Study of 1799 Toddlers.

Childhood vaccination is crucial to protect young children from harmful infectious diseases. This study aimed to investigate the recent childhood immunization rate of recommended and additional vaccinations and identify the factors affecting the vaccination uptake of young children in Hong Kong. The self-administrated questionnaires were distributed to parents of toddlers aged 2 to 5. They were asked to provide information on (1) socioeconomic demographic factors; (2) experiences during pregnancy; and (3) the medical history of the toddler. A total of 1799 responses were collected. Children were more likely to be fully vaccinated when they were at a younger age (aOR = 0.61, 95% CI: 0.48-0.78, < 0.001), the first child in the family (aOR second-born = 0.62, 95% CI: 0.48-0.81, < 0.001; aOR third-born = 0.33, 95% CI: 0.19-0.55, < 0.001), had a higher household income (aOR HKD 15,000-HKD 29,999 = 1.80, 95% CI: 1.27-2.55, = 0.001; aOR ≥ HKD 30,000 = 3.42, 95% CI: 2.39-4.90, < 0.001; compared with