Chlamydia retesting remains low among young women in Australia: an observational study using sentinel surveillance data, 2018-2022

Background Chlamydia remains the most notified bacterial sexually transmissible infection in Australia with guidelines recommending testing for re-infection at 3 months post treatment. This paper aimed to determine chlamydia retesting and repeat positivity rates within 2-4 months among young women in Australia, and to evaluate what factors increase or decrease the likelihood of retesting.Methods Chlamydia retesting rates among 16-29-year-old women were analysed from Australian Collaboration for Coordinated Enhanced Sentinel Surveillance of sexually transmissible infection and bloodborne virus (ACCESS) sentinel surveillance data (n = 62 sites). Among women with at least one positive test between 1 January 2018 and 31 August 2022, retesting counts and proportions within 2-4 months were calculated. Logistic regression was performed to assess factors associated with retesting within 2-4 months.Results Among 8758 women who were positive before 31 August 2022 to allow time for follow up, 1423 (16.2%) were retested within 2-4 months, of whom 179 (12.6%) tested positive. The odds of retesting within 2-4 months were 25% lower if tested in a coronavirus disease 2019 (COVID-9) pandemic year (2020-2022) (aOR = 0.75; 95% CI 0.59-0.95). Among 9140 women with a positive test before 30 November 2022, 397 (4.3%) were retested too early (within 7 days to 1 month) and 81 (20.4%) of those were positive.Conclusions Chlamydia retesting rates remain low with around a sixth of women retested within 2-4 months in line with guidelines. Re-infection is common with around one in eight retesting positive. An increase in retesting is required to reduce the risk of reproductive complications and onward transmission. Chlamydia remains as the most notified bacterial sexually transmissible infection in Australia and repeat infections can lead to significant reproductive complications, particularly for women. Guidelines recommended retesting at 3 months following a chlamydia diagnosis, but current retesting rates in line with guidelines are low, and re-infections are common. Increased efforts to improve timely retesting can aid in earlier identification, management and reduced risk of disease burden.