TTG is derived using the TGI modelling approach, and this metric summarizes a patient's tumour growth rate, tumour growth inhibition rate and drug efficacy decay [ 28].
Alternatively, for those parameters not included in the formal sensitivity analysis, such as vaccine efficacy, decay rate of efficacy, transmission, or the use of a booster dose, model outputs from several scenarios can be saved and compared.
Model functionality was demonstrated by estimating the public health impact of a hypothetical pre-erythrocytic malaria vaccine with 85% efficacy against uncomplicated disease and a vaccine efficacy decay rate of four years, based on internationally-established targets.
34, 35 The observed data of falciparum malaria episodes and the simulated efficacy decay of DDT and Deltamethrin showed that IRS with DDT did not reduce falciparum malaria episodes, but IRS with Deltamethrin did.
The distributed TBV is mass-distributed to 90% of all persons, with a 50% initial efficacy exponentially decaying with a four-year time constant.
Estimates of the public health impact of a vaccine are generated based on the type of vaccine, initial efficacy and decay rate of vaccine efficacy against infection, mode of vaccine delivery, and transmission setting.
The simulated effects in Namawala of a PEV with efficacy exponentially decaying with a four-year time constant mass distributed every two years is shown in Figure 5A and B. Baseline transmission is high enough that only minor perturbations are seen in prevalence, slightly increasing the seasonal oscillation as expected, and no discernible change occurs in EIR.
The decay in blocking efficacy further compounds the decay in killing efficacy, as would be expected when an ITN develops holes.
In their paper, they found that as soon as these methods were published, their efficacy began to decay, probably because other investors soon copied them.
These values of efficacy and its decay were selected for the demonstration scenario as they were expected to be broadly consistent with targets set by the international community [ 19].
