The UK's Office of National Statistics and the CDC are both estimating that we have nearly 25% immunity in the US and UK:
Characteristics of people testing positive for COVID-19 from the COVID-19 Infection Survey; antibody data by UK country, and region and occupation for England.
www.ons.gov.uk
Supposedly, this estimate accounts for antibodies becoming undetectable after some amount of time. Whether that's a conservative estimate or not, they definitely aren't suggesting immunity is close to half. We did seem to peak in daily cases a week after New Years Day but it mostly leveled instead of dropping... until this past weekend. Hopefully the steeper drop we are seeing now is more than just an artifact of the 3-day weekend (MLK Day). Regardless, this isn't a time to be relaxing. I'll be getting my mother (65+) and hopefully myself (caregiver) vaccinated as soon as humanly possible.