>"The flu often has a value of around 2, meaning the average infected person will infect two others before they're over it." The R0 value refers to the potenti

>"The flu often has a value of around 2, meaning the average infected person will infect two others before they're over it." The R0 value refers to the potential for infection (ie in a 100% susceptible population it would be what you wrote). >"But on a society-wide basis, if every person were vaccinated, that would effectively knock the R0 value from 2 to 1, which is huge. Transmission is exponential: if you infect two people and they infect two people and they infect two people, etc., the total number of infected looks dramatically different than if everybody only infects one person." I just wrote a little SIR model and did not see this behavior. Depending on the parameters either 100% of the susceptible population was eventually infected, the infection died out quickly, or, if turnover was high enough (eg birth/death/viral mutation leading to a constant stream of susceptibles), there was a cycle and about the same number of people got infected either way. Do you have a source for this behavior so I can see the details of the model?