Fig. 1.

Duration of post-treatment prophylaxis. Posterior estimates of the median duration of protection (a) and the proportion of the population still having drug levels which would protect them from reinfection, over time since first dose with either AS-AQ (b) or AL (c). In b and c, the solid lines show the median estimate across trial sites, while the dotted lines show the different estimates for each of the 12 trial sites. The equations of the lines in b and c are reverse cumulative gamma distributions and can be implemented for example in R as 1-pgamma(t, shape = r, scale = λ), where t is time in days, and r and λ are the shape and scale parameters of the gamma distribution, respectively. For AL, r = 93.5 and mean λ = 0.139. For AS-AQ, r = 16.8 and mean λ = 0.906. The mean of each gamma distribution rλ gives the duration of protection from each drug. The site-specific lines can be calculated using the median durations of prophylaxis in Table 1, and the same shape parameter (assumed not to vary between sites for each drug)