Are CoronaMelder codes exchanged through walls, and does this mean I can get a notification?
CoronaMelder does not know whether a signal is coming from another telephone that is on the other side of a wall or floor. CoronaMelder only measures how strong the signal is: the stronger that signal, the closer you are to the other user.
An extensive test was carried out in April 2021, which also examined the effect of walls and floors. This shows that walls and floors generally attenuate the signal of a telephone. As a result, CoronaMelder does not measure such contact as risky in most cases. In 87% of cases, users are therefore not notified if the person who reported an infection in the app was on a different floor or in a different room / house.
See also: How reliable is a report?