AIDS and Behavior

, Volume 23, Issue 7, pp 1780–1789 | Cite as

High Adherence to HIV Pre-exposure Prophylaxis and No HIV Seroconversions Despite High Levels of Risk Behaviour and STIs: The Australian Demonstration Study PrELUDE

  • Iryna B. ZablotskaEmail author
  • Stefanie J. Vaccher
  • Mark Bloch
  • Andrew Carr
  • Rosalind Foster
  • Andrew E. Grulich
  • Rebecca Guy
  • Anna McNulty
  • Catriona Ooi
  • Catherine Pell
  • Isobel M. Poynten
  • Garrett Prestage
  • Nathan Ryder
  • David Templeton
  • the PrELUDE Study Group
Original Paper


PrELUDE study evaluated daily pre-exposure prophylaxis (PrEP) in high-risk individuals in Australia. This open-label, single-arm study tested participants for HIV/STI and collected behavioural information three-monthly. We report trends over 18 months in medication adherence, side-effects, HIV/STI incidence and behaviour. 320 gay/bisexual men (GBM), 4 women and 3 transgender participants, followed on average 461 days, reported taking seven pills/week on 1,591 (88.5%) occasions and 4-6 pills/week on 153 (8.5%) occasions. No HIV infections were observed. STI incidence was high and stable, while gonorrhoea infections declined from 100.0 to 25.8/100 person-years between 6 and 15 months (p < 0.001). The number of HIV-positive and unknown-status sex partners, and condomless anal intercourse, significantly increased. In this high-risk cohort of mainly GBM, increases in risk behaviours and high STI incidence were not accompanied by HIV infections due to high adherence to daily PrEP. The study informed policy and further PrEP implementation among Australian GBM.


Gay and bisexual men HIV prevention Pre-exposure prophylaxis Sexually transmitted infections HIV/STI incidence Side-effects Behaviour 



PRELUDE Study Team: Mark Bloch, Andrew Carr, Ching (Yvonne) Cheung (study clinical coordinator), Rosalind Foster, Chris Gianacas (clinical data manager), Andrew Grulich, Rebecca Guy, Martin Holt, John Kaldor, Brent Mackie, Kenneth Mayer, John McAllister, Anna McNulty, Dean Murphy, Catriona Ooi, Catherine Pell, Isobel Mary Poynten, Garrett Prestage, Nathan Ryder, David Templeton, Stefanie Vaccher (behavioural data manager), John de Wit, Edwina Wright, and Iryna Zablotska (chief investigator and protocol chair). Participating clinics: Clinic 16 at Royal North Shore Hospital, Holdsworth House Medical Practice, Newcastle Sexual Health Service, RPA Sexual Health, St Vincent’s Hospital HIV Immunology and Infectious Diseases Unit, Sydney Sexual Health Centre, Taylor Square Private Clinic, and Western Sydney Sexual Health Centre. Community partner organisations: ACON (formerly AIDS Council of NSW) and Positive Life NSW.

Author Contributions

IBZ, AEG, RG, IMP and GP were involved in the conception and design of the study. IBZ was the Protocol Chair. SJV, MB, AC, RF, AM, CO, CP, NR and DT oversaw participant recruitment and data collection. IBZ and SJV conducted the analysis. IBZ wrote the manuscript with input from all co-authors. All authors met the International Committee of Medical Journal Editors criteria for authorship, and read and approved the final manuscript.


The study was funded by the NSW Ministry of Health. Gilead Sciences provided the study medication, Truvada®. The views expressed in this publication do not necessarily represent the position of these organisations.

Compliance with Ethical Standards

Ethical Approval

The study protocol was reviewed and approved by the St Vincent’s Hospital Human Research Ethics Committee (HREC) in Sydney, NSW (Protocol #HEPP 1403; identification #HREC/14/SVH/130) and was registered at (identifying #NCT02206555).


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Iryna B. Zablotska
    • 1
    • 2
    Email author
  • Stefanie J. Vaccher
    • 1
  • Mark Bloch
    • 3
  • Andrew Carr
    • 4
  • Rosalind Foster
    • 1
    • 5
  • Andrew E. Grulich
    • 1
  • Rebecca Guy
    • 1
  • Anna McNulty
    • 6
  • Catriona Ooi
    • 7
    • 8
  • Catherine Pell
    • 9
  • Isobel M. Poynten
    • 1
  • Garrett Prestage
    • 1
  • Nathan Ryder
    • 10
  • David Templeton
    • 1
    • 11
  • the PrELUDE Study Group
  1. 1.The Kirby InstituteUNSW SydneySydneyAustralia
  2. 2.Sydney Medical School - Westmead, Western Sydney Sexual Health CentreUniversity of SydneyParramattaAustralia
  3. 3.Holdsworth House Medical PracticeSydneyAustralia
  4. 4.St. Vincent’s HospitalSydneyAustralia
  5. 5.Clinic 16 Northern Sydney Sexual HealthRoyal North Shore Community Health CentreSt LeonardsAustralia
  6. 6.Sydney Sexual Health CentreSydneyAustralia
  7. 7.Western Sydney Sexual Health CentreWestern Sydney Local Health DistrictParramattaAustralia
  8. 8.Centre for Infectious Diseases and Microbiology, Westmead Clinical SchoolUniversity of SydneySydneyAustralia
  9. 9.Taylor Square Private PracticeSydneyAustralia
  10. 10.Pacific ClinicNewcastleAustralia
  11. 11.RPA Sexual Health, Sydney Local Health District and Central Clinical SchoolThe University of SydneySydneyAustralia

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