The Public Health Agency of Sweden claimed on a press conference that in Stockholm (Sweden's epicenter for covid) there were 999 undetected cases for every confirmed one.
There are 6189 confirmed cases in the Stockholm region and with this math, there would be 6 million total cases. The problem being that there are only 2.3 million people living there.
Obviously they had it wrong and had to retract.
https://www.folkhalsomyndighet... (in Swedish)
Another study, based on only 100 tests where 11 people showed to have antibodies against covid-19 also had to be retracted. The reason? They had included blood that came from previous covid-19 patients that had donated blood to extract plasma from.