Assessment of herd immunity and cross-protection after a human papillomavirus vaccination programme in Australia: a repeat cross-sectional study

Sepehr N Tabrizi, Julia Brotherton, John Martin Kaldor, S Rachel Skinner, Bette Liu, Deborah Bateson, Kathleen Margaret McNamee, Maria Garefalakis, Samuel Phillips, Eleanor Cummins, Michael Malloy, Suzanne M Garland

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171 Citations (Scopus)


BACKGROUND: After the introduction of a quadrivalent human papillomavirus (HPV) vaccination programme in Australia in April, 2007, we measured the prevalence of vaccine-targeted and closely related HPV types with the aim of assessing direct protection, cross-protection, and herd immunity. METHODS: In this repeat cross-sectional study, we recruited women aged 18-24 years who attended Pap screening between October, 2005, and July, 2007, in three major metropolitan areas of Australia to form our prevaccine-implementation sample. For our postvaccine-implementation sample, we recruited women aged 18-24 years who attended Pap screening in the same three metropolitan areas from August, 2010, to November, 2012. We compared the crude prevalence of HPV genotypes in cervical specimens between the prevaccine and the postvaccine implementation groups, with vaccination status validated against the National HPV Vaccination Program Register. We estimated adjusted prevalence ratios using log linear regression. We estimated vaccine effectiveness both for vaccine-targeted HPV types (16, 18, 6, and 11) and non-vaccine but related HPV types (31, 33, and 45). FINDINGS: 202 women were recruited into the prevaccine-implementation group, and 1058 were recruited into the postvaccine-implementation group. Crude prevalence of vaccine-targeted HPV genotypes was significantly lower in the postvaccine-implementation sample than in the prevaccine-implementation sample (58 [29 of 202 vs 69 [7 of 1058; p
Original languageEnglish
Pages (from-to)958 - 966
Number of pages9
JournalLancet Infectious Diseases
Issue number10
Publication statusPublished - 2014

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