Simulated longitudinal study for evaluation of the association between protection from infection and pre-erythrocytic antibodies. It is assumed that 50 volunteers are followed for 12 weeks with active detection of infection. (A) Log-normal distribution of antibody titres in the study cohort, split into high (blue) and low (red) responders. (B) Dose–response curve used in model simulations for the probability of being protected by antibodies. (C) Distribution of transmission efficiency in the study population, split into high (blue) and low (red) responders. (D) Sample Kaplan-Meier curves for high and low responders. The red and blue shaded regions represent 95% confidence intervals for the KM curves of low and high responders, respectively. The substantial overlap between the shaded regions illustrates the low statistical power to differentiate between high and low responders.