[Surfacing Hidden Design: A Better Alternative To Interrelated Mutable Fields](http://wp.me/p3ui6n-1q) - 1) Design hidden in primitive mutable fields and methods

EpidemySimulator_Primitive.scala

class Person (val id: Int) {
  
  var infected = false
  var sick = false
  var immune = false
  var dead = false

  // to complete with simulation logic
  // [infection progression]
}