Systems and methods include the following. Information about a first electronic communication device is transmitted to at least one server and/or decentralized infrastructure. The information includes vicinity information. A status signal associated with a first user of the first electronic communication device is optionally transmitted. Contact proximity network information about a contact proximity network is received. The contact proximity network is based on the information from a plurality of electronic communication devices and information about the association between users and electronic communication devices. The contact proximity network information includes status signal information and interconnected nodes corresponding to different users and pairwise connections between users based upon their relative physical space and time proximity. A notification indicating a network-based proximity of a first user to a second user is provided, indicating a minimum number of connections between the first user and the second user during a specified time frame.