Fig. 5: Posterior probability estimates for unclassified evaluation units (EUs).

A Probability of need or no need for trachoma program intervention in unclassified EUs. Unclassified EUs included baseline surveys in new populations that did not have PCR data (Sudan, Peru), opportunistic surveys not focused on trachoma (Malaysia), settings with unusual epidemiology based on trachoma biomarkers (Papua New Guinea, Vanuatu), and those that failed to achieve a consensus classification into ‘Action not needed‘ and ‘Action needed‘ categories (five from Ethiopia and Malawi). The posterior probability was calculated using seroconversion rate (SCR) estimates among 1–5-year-olds in a Bayesian mixture model that assumed prior probabilities of 80% for ‘Action not needed‘ and 20% for ‘Action needed‘. EUs are ordered by increasing median SCR value shown in (B). B EU-specific SCR density distributions, with an example threshold shown at 2.2 per 100 person-years. C An illustrative threshold of 2.2 per 100 person-years corresponding to the 90% posterior probability (’+’ in Fig. 3) was used to calculate the empirical probability of ‘Action not needed‘ as the proportion of the SCR density distribution ≤2.2. Table 1 includes additional details for the unclassified EU populations.