A: Health departments are notified when an individual tests positive for COVID-19.
Contact tracing staff reach out to new cases by phone to determine who (i.e., friends, family, co-workers) they may have had close contact with (within 6 ft) beginning with the days leading up to the onset of their symptoms, as well as what events or public spaces they may have visited during that time frame. Cases are asked about how long they may have been in close contact with individuals. Based on this information, staff will determine if a contact is at low, medium or high risk of contracting COVID-19. Cases also provide the contact information for those individuals, if known. Contact tracing staff will then call, email or send a letter to contacts who are at medium or high risk, to notify them they had contact with a case of COVID-19 (the identity of the case is not disclosed). Staff also provide instructions for self-quarantine (for 14 days since it can take that long to develop symptoms) and monitoring of symptoms. See here for an explanation from WI health officials of how contacts are traced.
Many states are hiring additional contact tracing staff so they can quickly identify the contacts of new cases and direct them to self-quarantine which is key to stopping further transmission (see example here). As testing capacity scales up, even potential cases (contacts to cases that haven’t yet developed symptoms) could be tested, allowing for quicker identification of new cases and their contacts. Having adequate staff and systems in place for contact tracing will be essential for relaxing social distancing measures in order to deal with not just a potential surge of cases, but also larger pools of contacts resulting from more social interactions taking place.
What about electronic apps? Other countries have started to utilize technology to aid in the contact tracing process (see example from Germany here). One example is the Pan-European Privacy Preserving Proximity Tracing system. With this system, doctors would get permission from those who test positive to put their information into a central server. Users of the app would opt-in and proximity of the users phone to other cellphones would be logged using Bluetooth technology (without storing data from location tracking). Users would then receive a message if they’ve been in close contact with someone (i.e., were near that persons phone) who has tested positive for COVID-19. Instructions for self-quarantine and monitoring of symptoms could then be provided.
With proper privacy protections, such technology could make it much easier to notify individuals they were in contact with a case at a large event, at the grocery store or other setting in which it is normally nearly impossible to identify and follow-up with all contacts to cases. Quicker initiation of self-quarantine of contacts, would mean less spread of infection before individuals develop symptoms and/or are tested themselves.
