The mathematicians and statisticians are weighing in and believe the herd immunity threshold to be in the 10-20% range (not 80% like epidemiologists keep regurgitating).
https://www.medrxiv.org/content/10.1101/2020.07.23.20160762v1.full.pdf
https://www.medrxiv.org/content/10.1101/2020.07.23.20160762v1.full.pdf