Measles immunity and immunisation status in Australian children 1 to 4 years of age

Aim: Determine measles seropositivity and vaccine coverage in children aged 1 to 4 years inclusive. Compare data in those who produced immunisation records and those who relied on parental recall. Establish variables associated with seropositivity. Methods: Design: Population- and area-based, cluster sample of 1- to 4-year-olds; households surveyed by trained interviewer. Setting: Australia-wide, excluding New South Wales. Questionnaires completed between February and April 1995. Subjects: 2117 completed questionnaires were returned for children aged 1 to 4 years, 923 of whom provided a sufficient blood sample for analysis. Results: Overall seropositivity was 86% for the 923 children tested and was strongly associated with previous immunisation (P < 0.001) and age (P < 0.001), but not with parental report of a previous measles diagnosis (P = 0.581). Eight hundred and forty-three (91%) reported previous measles immunisation, with 760 (90%) of these testing seropositive. Four hundred and ninety-one (55%) parents/guardians produced immunisation records, while 400 (45%) relied on recall. Immunised children whose parents relied on recall were equally likely to be seropositive as children whose parents produced records. The 923 children tested were representative of the 2117 who completed questionnaires in all factors except age, where children below 2 years old were under represented (P < 0.001). Conclusions: These data support the current second routine measles immunisation prior to school entry, and reinforce the need to promote the first routine dose to achieve measles elimination.