https://www.mercurynews.com/2020/05/20/swedish-antibody-study-shows-little-sign-of-herd-immunity/

By Johan Ahlander and Niklas Pollard | Reuters

STOCKHOLM – A Swedish study found that just 7.3 percent of Stockholmers developed COVID-19 antibodies by late April, which could fuel concern that a decision not to lock down Sweden against the pandemic may bring little herd immunity in the near future.