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Background: The aims of this study were to determine the impact of the Australian Measles Control Campaign (MCC) on the transmission dynamics of measles by calculating the reproductive number (R) before and after the MCC, and to predict measles control in Australia in the future., Methods: A national serosurvey was conducted before and after the MCC. Sera were tested for anti-measles IgG using enzyme immunoassay (EIA). A mathematical model, using serosurvey results and vaccine coverage estimates, was used to calculate the change in R after the MCC., Results: The values of R calculated before and after the MCC were 0.90 and 0.57. At vaccine coverage levels indicated by the Australian Childhood Immunisation Register (ACIR), the value of R will exceed 1 (the epidemic threshold) in 2007-2008 nationally, and sooner in some regions of Australia. Coverage of at least 84% with two doses of MMR is required to sustain measles control., Conclusions: The Australian MCC had a significant impact on the transmission dynamics of measles. However, current vaccine coverage levels may result in indigenous measles transmission by 2007. Sustained efforts are required to improve coverage with two doses of MMR and to ensure elimination of indigenous measles transmission.

To evaluate the impact of the 1998 Australian Measles Control Campaign on immunity to measles and rubella, 4400 opportunistically-collected sera, submitted to diagnostic laboratories across Australia from subjects aged 1-49 years, and 3000 from subjects aged 1-18 years, were tested before and after the campaign, respectively. The proportion of individuals aged 1-18 years who were immune to measles rose from 85% before, to 90% after, the campaign (P < 0.001). The greatest increase was in preschool (7%, P < 0.001) and primary school (10%, P < 0.001) children, who were actively targeted by the campaign. Rubella immunity in 1-18 year-olds rose from 83% to 91% (P < 0.0001), again with significant increases in preschool (4%, P = 0.002) and primary school (16%, P < 0.001) children. 94% of individuals aged 19-49 years were immune to rubella. These serosurveys confirm other evidence of the effectiveness of the Australian Measles Control Campaign and demonstrate the value of serosurveillance using opportunistically collected sera.

The 1998 Australian Measles Control Campaign had as its aim improved immunization coverage among children aged 1-12 years and, in the longer term, prevention of measles epidemics. The campaign included mass school-based measles-mumps-rubella vaccination of children aged 5-12 years and a catch-up programme for preschool children. More than 1.33 million children aged 5-12 years were vaccinated at school: serological monitoring showed that 94% of such children were protected after the campaign, whereas only 84% had been protected previously. Among preschool children aged 1-3.5 years the corresponding levels of protection were 89% and 82%. During the six months following the campaign there was a marked reduction in the number of measles cases among children in targeted age groups.