Several communities, including towns in Sweden, have reached herd immunity and do not know it.
"In this study we run our model with a pre-existing immunity of 62% for Stockholm, which we base on a new mathematical method which estimates the pre-immunity directly from a time series of cases and available sero prevalence information [24]. Applying this to the Stockholm county second wave (red curve in Figure 3), gave an immunity level of 72%, which would correspond to a pre-pandemic immunity of 62% (upon subtracting the 10% having developed COVID-19 anti-bodies by September 2020)."
Why get a vaccine against a virus you already had and are immune to? Check it out.
https://www.medrxiv.org/content/10.1101/2021.07.07.21260167v1
Why is this not being talked about?
The CDC also has interesting blood donor sero- prevalence information on their website.
https://covid.cdc.gov/covid-data-tracker/#nationwide-blood-donor-seroprevalence
Maybe Sweden had the right idea with this virus. They just needed to protect their elderly better.