GAO-20-666SP 1 (2020-07-28)

handle is hein.gao/gaobaebko0001 and id is 1 raw text is: 


                             Science,   Technology   Assessment,
        GAO                  and  Analytics




SCIENCE & TECH SPOTLIGHT:

CONTACT TRACING APPS


What  is it? Contact tracing is a process in which public health officials
attempt to limit disease transmission by identifying infected individuals,
notifying their contacts-all the people they may have transmitted
the disease to-and  asking infected individuals and their contacts to
quarantine, if appropriate (see fig. 1). For a highly contagious respiratory
disease such as  COVID-19,  a contact could be anyone who  has been
nearby. Proximity tracing applications (apps) can expedite contact tracing,
using smartphones  to rapidly identify and notify contacts.


    Individual not infected Infected, contagious, without symptoms
  * Infected, contagious, and showing symptoms
    Measure to reduce transmission, such as quarantine
Source: Marcel Salathe and Nicky Case. I GAO-20-666SP


Figre  ,A simplified depiction of disease transmission. Through contact tracing, an infected
individual's contacts are notified and may be asked to quarantine. (In reality, some contacts
may not become infected, and some of those infected may not show symptoms.)

How  does  it work? In traditional contact tracing, public health officials
begin by identifying an infected individual. They then interview the
individual to identify recent contacts, ask the individual and their contacts
to take containment measures,  if appropriate (e.g., a 14-day quarantine
for COVID-19), and  coordinate any needed  care and testing. Proximity
tracing apps may accelerate the process by replacing the time-consuming
interviews needed to identify contacts. Apps may also identify more
contacts than interviews, which rely on interviewees' recall and on their
being acquainted with their contacts.

Public health authorities provide the apps, often using systems developed
by companies  or research groups. Users voluntarily download the app for
their country or region and opt in to contact tracing. In the U.S., state or
local public health authorities would likely implement proximity tracing apps.


Proximity tracing apps detect contacts using Bluetooth, GPS, or a
combination  of both. Bluetooth-based apps rely on anonymous  codes
shared between  smartphones   during close encounters. These codes
contain no information about location or user identity, helping safeguard
privacy. The apps allow public health authorities to set a minimum time
and distance threshold for someone  to count as a contact.

Contact tracing can be centralized or decentralized. With a centralized
approach, contacts identified by the app are often saved to a government
server, and an official notifies contacts of possible exposure. For a
decentralized approach, contact data are typically stored on the user's
device at first. When a user voluntarily reports infection, the user's codes
are uploaded to a database that other app users' phones search. Users
who  have encountered  the infected person then receive notifications
through the app (see fig. 2).


      915 PNONVE C/4ECK<
      THIE DR&598SE FOR
      CODES OF THOSE WHO       THE APPALERTS   TO
      HAVE  T EST3D POS        P
      Source: GAO analysis of literature related to various proximity tracing apps. I GAO-20-666SP

Fgure 2. Bluetooth-based proximity tracing apps exchange information, notify contacts
exposed to an infected person, and provide follow-up information.


GAO-20-666SP Contact Tracing Apps

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