This dataset is associated with NSW Koala Research Plan project 2019_07: Vaccination against chlamydiosis – an effective disease management tool in wild populations? It contains spatial data on koala capture locations and Chlamydia pecorum infection status determined using qPCR diagnostics. The data were collected as part of a field‑based vaccination study evaluating the effectiveness of a synthetic peptide vaccine in wild koala populations. The dataset underpins the following publication: Simpson, S.J., Higgins, D.P., Timms, P., Mella, V.S.A., Crowther, M.S., Fernandez, C.M., McArthur, C., Phillips, S., & Krockenberger, M.B. (2023). Efficacy of a synthetic peptide Chlamydia pecorum major outer membrane protein vaccine in a wild koala (Phascolarctos cinereus) population. Scientific Reports, 13, 15087. https://doi.org/10.1038/s41598-023-42296-7