Your numbers aren't adding up. 320,098/10,099,265=3.2%Using those model’s estimates, Sweden’s number of confirmed cases (320,098 as of today) in their overall population of (10.23 million) suggests that they are probably around 19-25% of their population already infected.
EDIT: You're using predictive modeling. Nevermind.
I thought you were originally asking about articles referencing what is needed to obtain herd immunity. The article citing 15% seroprevalence was SAGE Journals: Your gateway to world-class research journals (it's from August, so a little old).
Regardless, my point was that the 70% prevalence to obtain herd immunity is nowhere near that. My point wasn't 15 vs 19%.