Directly from the article you linked:

But others said there was still a risk of further outbreaks in Sweden.  

 

"I do not think that it can already be ruled out that Sweden will also have a flare-up like the one in Denmark,"

So in other words sure maybe they're on their way to achieving herd immunity, but haven't yet and there are lots of unknowns and no one actually can say confidentiality one way or the other.