I am doing a project about the SEIR model, which is an epidemic model consisting of 5 ODEs, that classifies people according to 5 categories: S: Susceptible E: Exposed I: Infected R: Recovered I am looking into CDC's website and would like to take Flu as an example. My medical knowledge is limited so I am finding difficulty interpreting the reports. For example, here is a recent report. If I understand correctly, the report provides data about (some of the) infected people only. There is no data about how many has recovered. Also, I am not sure how can find any data about what fraction of people are susceptible and what are exposed?