"We do not currently recommend face masks in public settings since the scientific evidence around the effectiveness of face masks in combatting the spread of infection is unclear. However, there may be situations where face masks can be useful despite the uncertain state of knowledge about the effects.
Face masks must always be seen as complementary to other recommendations: stay at home when you have symptoms, wash your hands regularly and keep at a distance from others."
- https://www.folkhalsomyndigheten.se/the-public-health-agency...
As a source for this they have this page with 37 different papers/studies: https://www.folkhalsomyndigheten.se/smittskydd-beredskap/utb...
So... the science depend a lot of who you ask and the context of the statement.