BACKGROUND: Universal childhood vaccination programmes form a core component of child health policies in most countries, including the UK. Achieving high coverage rates of vaccines is critical for establishing 'herd immunity' and preventing disease outbreaks. Evidence from the UK has identified several groups of children who are at risk of not being fully immunised. Our aim was to determine whether children with intellectual disabilities constitute one such group.

METHODS: Secondary analysis of parental report data on child vaccination collected in the UK's Millennium Cohort Study when the children were 9 months, 3 years, 5 years and 14 years old.

RESULTS: With one exception (MMR coverage at age 5) vaccination coverage rates were lower for children with intellectual disabilities (when compared to children without intellectual disability) for all vaccinations at all ages. Complete coverage rates were significantly lower for children with intellectual disabilities at ages 9 months (unadjusted PRR non-vaccination = 2.03 (1.14-3.60), p < 0.05) and 3 years (unadjusted PRR = 2.16 (1.06-4.43), p < 0.05), but not at age 5 years (unadjusted PRR = 1.91 (0.67-5.49)). HPV vaccination was lower (but not significantly so) at age 14 (PRR = 1.83 (0.99-3.37), p = 0.054). Adjusting PRRs for between group differences in family socio-economic position and other factors associated with coverage reduced the strength of association between intellectual disability and coverage at all ages. However, incomplete vaccination remained significantly elevated for children with intellectual disabilities at ages 9 months and 3 years. There were no statistically significant differences between parents of children with/without intellectual disability regarding the reasons given for non-vaccination.

CONCLUSIONS: Children with intellectual disabilities in the UK are at increased risk of vaccine preventable diseases. This may jeopardise their own health, the health of younger siblings and may also compromise herd immunity.