How Herd Immunity Works — And What Stands In Its Way

For much of 2020, herd immunity was put forward as this borderline genocidal illusion of just letting this pandemic run its course until enough people have become immune by infection. We’re now on the proper, albeit slow path towards herd immunity by vaccination. Time for some simulations: How does herd immunity work? How do more infectious variants factor in? How useful is a vaccination rate of 30%, well below herd immunity?