In the SEIR model, we introduce an additional compartment. The yellow curve of exposed individuals rises before the red peak of infections. These are people already infected but not yet infectious. This latent stage delays the outbreak and shifts the timing of the epidemic peak. In the second phase, the familiar pattern returns: green declines as susceptibles diminish, while blue rises as recoveries accumulate. With an R-nought of 3.0, the resulting wave is markedly strong.
