Epidemic Models and Protective Mutations

The paper proposes and discusses an epidemic model which assumes that a population, affected to a disease, is (partially) protected from the disease. These protections may be generated by some inherited genetic mutations; mutations favoured by the presence, in the past, of a deadly endemic disease (the Haldane hypothesis). The protections can also have a non-genetic origin: the cause can be the age or the sex of the subjects; in this case the model can only be applied for short periods, typically in the early stages of the epidemic. Anyway we shall see that the presence of these protections, if wisely managed, not only does it benefit the whole population, but it also makes the measures taken to contain the epidemic more effective.