When a patient is diagnosed with an infectious disease like COVID-19,
an important step in slowing the transmission of the disease is contact tracing.
Contact tracing seeks to identify the people who have had close contact
with the infected individual, and who therefore may be infected themselves.
This targeted strategy reduces the need for stay at home periods.
However, manual contact tracing is subject to a person's ability to recall everyone
they have come in contact with over a two-week period.
There is need for an automated, privacy-preserving, contact-tracing system.
MIT is developing one such system.
Cell phones are constantly advertising their presence using Bluetooth.
These advertisements, which we call "chirps," can be anonymous,
and contain no location data or personally identifiable information.
Every phone stores a list of all the chirps that is has sent,
and all the chirps it has overheard from nearby phones within arm's reach.
The MIT system utilizes these lists to enable contact tracing
for people diagnosed with COVID-19.
This system not only identifies contacts, it also estimates the distance between individuals
as well as the amount of time they spent in close proximity to each other.
When a person is diagnosed with COVID-19,
public health professionals would coordinated with the patient
to upload the list of chirps sent out by their phone to a public database.
Meanwhile, people who have not been diagnosed
can have their phones do a daily scan of the public database
to see if their phones have overheard any of the chirps
used by people later diagnosed with COVID-19.
This indicates that they were in close, prolonged contact with that anonymous individual.
Depending on the circumstances of contact,
They may be referred to the public health authorities,
who may recommend varying courses of action,
including symptom watch, testing, and self-quarantine.