So far there have been antibody studies published from the following areas:

LA County, CA
Santa Clara County, California
Boston/Chelsea, MA
Gangelt, Germany
Capitol Region, Denmark

There likely have been more that I'm not aware of.

They've all essentially come to similar conclusions about prevalence of previous SARS-CoV-2 infection, if seeing different rates of previous infection in a given location.

There are questions about the accuracy of antibody tests used, as well as methodologies used, small cohorts sampled, and lack of peer review to this point. Those are scientifically fair questions to ask, but what are the odds that five independent research teams from three different countries on two different continents checking five different population groups would ALL utilize the same (potentially) flawed tests and methodologies? Possible...but does not seem very scientifically probable.

One study is not actionable for policy, but at least five reporting similar results shows a trend. As more antibody studies are released in the coming weeks, we will see if those regional and local results align or differ from what has already been released.

Is all that "anecdotal"? Yes, I suppose so...but if you hear similar anecdotes from multiple different people in multiple different places, should they be dismissed simply due to a lack of peer review in the midst of crisis?