Poster Presentation Lancefield International Symposium for Streptococci and Streptococcal Diseases 2025

The Australian Strep A Vaccine Initiative (ASAVI) Urban Pharyngitis Surveillance Study (#55)

John Hart 1 2 3 , Ciara Baker 1 2 , Elizabeth Negus 1 4 , Tria Williams 1 2 5 , Maria Angel 1 2 , Matthew Cooper 1 4 , Hannah Frost 1 2 3 , Serene Yeow 1 2 , Jasmyn Voss 1 2 , Taylor Mills 1 2 , Anna Takahashi 1 4 , Michael Morici 1 4 , Isabel Lester 1 4 , Angela D'Aprile 1 4 , Katherine Noonan 1 4 , Rachel Canaway 1 3 , Peter Richmond 1 4 , Margie Danchin 1 2 3 5 , Helen Marshall 1 6 , Lena Sanci 1 3 , Alan Leeb 1 4 , Glenn Pearson 1 4 , Alma Fulurija 1 4 , Jonathan Carapetis 1 4 , Andrew Steer 1 2 3 5
  1. The Australian Strep A Vaccine Initiative, Australia
  2. Murdoch Children's Research Institute, Parkville, VIC, Australia
  3. The University of Melbourne, Melbourne, Australia
  4. The Kids Research Institute Australia, University of Western Australia, Perth, Australia
  5. The Royal Children's Hospital, Melbourne, Australia
  6. Women's and Children's Health Network and the University of Adelaide, Adelaide, Australia

Background

The Australian Strep A Vaccine Initiative (ASAVI) has the goal of developing a safe, effective, and affordable Streptococcus pyogenes vaccine. This study aims to provide the necessary incidence and prevalence data to conduct S. pyogenes vaccine trials for pharyngitis prevention.

Methods

We conducted a prospective multi-centre cohort study enrolling children aged 3-14 years via general practice and self-nomination. A throat swab and blood sample were collected at baseline and 4-6-month intervals over 12 months, and a throat swab at sore throat trigger visits. Throat swabs were analysed to detect S. pyogenes using microbiological culture, and a point-of-care nucleic acid amplification test (NAAT) for sore throat samples. Convalescent blood samples were collected 3-5 weeks after sore throat visits if S. pyogenes was detected on NAAT. Serum anti-streptolysin O and anti-DNase B antibody titres will be assessed using established serological methods to indicate recent S. pyogenes infection.

Results

Between 14/07/2021 and 19/07/2023, 476 participants were recruited, 308 at sites in Melbourne and 168 in Perth. Two hundred and thirty-seven participants (50%) were male and 7 (1.5%) were of Aboriginal background. Laboratory analysis is underway. Incidence of all sore throat; S. pyogenes positive sore throat, based on microbiology and NAAT; and serologically confirmed S. pyogenes sore throat will be presented at the meeting. Prevalence of S. pyogenes carriage at the baseline and healthy seasonal visits will also be presented.

Conclusion

This study will establish the baseline S. pyogenes epidemiology that is critical to demonstrate safety and efficacy of a lead vaccine candidate.