What is Herd Immunity and How Can We Achieve It With COVID-19?

https://www.jhsph.edu/covid-19/articles/achieving-herd-immunity-with-covid19.html

Global prediction of unreported SARS-CoV2 infection from observed COVID-19 cases

https://www.medrxiv.org/content/10.1101/2020.04.29.20083485v1