Background: An effective vaccine for Group A Streptococcus (Strep A) could prevent superficial, severe and immune-mediated illnesses. As part of Rapua - a Strep A vaccine initiative in Aotearoa New Zealand, the iSOoTH (Kids Sore Throat) study aimed to inform vaccine trial design, by determining the incidence of sore throats and Strep A pharyngeal positivity in Auckland children.

Methods: This prospective community-based cohort study enrolled 510 children aged 3-14 years between September 2023 and April 2024. The cohort comprised 12.1% Māori, 21.5% Pacific, 14.1% Asian and 52.3% NZ European children. Research nurses visited homes to collect throat swabs, saliva, and finger-prick blood samples at baseline, six and 12 months. Additional samples were collected by the study team if a child developed a sore throat. Sore throat episodes diagnosed by primary care providers and reported by participants were also captured.

Results: The cohort retention rate was 95%. Asymptomatic Strep A positivity at baseline was 22.3%, dropping to 15.7% at six-months and 11.8% at 12 months. A total of 181 participants reported one or more sore throat episodes, resulting in 296 sore throat visits, with 17.6% of symptomatic children testing positive for Strep A. Including self-reported positive swabs, 28.3% of sore throats were Strep A positive.

Conclusions: Asymptomatic Strep A throat swab positivity declined over the study period, likely reflecting shifting trends in Strep A epidemiology post-pandemic. Community-based recruitment utilising culturally responsive approaches resulted in rapid recruitment and high participant retention, highlighting Auckland’s suitability as a future clinical trial site.