A population-based survey of immunisation coverage in two-year-old children

A cross-sectional, population-based, cluster-sample survey of 187 children was conducted in the Newcastle area to assess the proportion of two-year-old children who were fully immunised, to ascertain whether administration of these vaccines was age-appropriate and to look for factors predicting incomplete immunisation. Parents or guardians were interviewed at their homes and the immunisation status of the children was verified either by the parent-held record or by the immunisation-provider-held record. Levels of full immunisation were 77 per cent at the time of interview and 72 per cent at the second birthday if Haemophilus influenzae type b (Hib) vaccine was excluded. If it was included, the full immunisation level was 51 per cent. Coverage was highest for oral polio vaccine and lowest for Hib vaccine. Twenty-nine per cent of all immunisations were given early, 44 per cent were given on time and 20 per cent were given late. Doses of vaccines due at older ages were more likely to be given late or not at all. Factors predicting incomplete immunisation were: the principal caregiver being aged under 25 years, being born outside Australia, having post-secondary qualifications, being female and having more than one child in the household. Immunisation coverage levels were not high enough to protect against outbreaks of pertussis and measles and cases of Haemophilus influenzae type b. Immunisation providers should aim to increase coverage to protect the population against all vaccine preventable diseases, and aiming at high-risk groups could more effectively do this.