So at week zero, we essentially have that pathogen invading our body. Infection takes place. Now, it's the first time that we are ever infected by that particular pathogenic antigen. And that means, at least initially, during the latent period, we're going to have a zero concentration of antibody in our blood because we're not going to have those antibodies that can bind specifically to that infecting antigen. However, over time, when the adaptive immune system actually is mobilized, it will have those plasma cells that will be able to produce those antibodies. And at that moment in time, we have the logarithmic phase taken to effect.