It's because new cases peaked at the end of April for Sweden, so the population is probably already most of the way towards herd immunity. How is that possible

It's because new cases peaked at the end of April for Sweden, so the population is probably already most of the way towards herd immunity. How is that possible? Two main theories are being explored: 1. The population didn't start out 100% susceptible like the models assume. Some large fraction of people may have pre-existing immunity from prior coronavirus infections. 2. The population is non-homogeneous. The models assume everyone is equally virulent and equally susceptible. If that assumption is changed and the models re-run, they show the epidemic taps out at about 15-20% infected. https://www.nicholaslewis.org/why-herd-immunity-to-covid-19-is-reached-much-earlier-than-thought/ https://www.nicholaslewis.org/why-herd-immunity-to-covid-19-...