Contact Tracing Apps Aim to Slow Spread of COVID-19

Apps can help alert you when you've been exposed to the novel coronavirus.

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As people around the world emerge from mandatory lockdowns and quarantines, health officials are working on ways to keep the spread of COVID-19 in check while allowing for more personal freedom. Contact tracing has been touted as one of the best ways to track and contain the spread of the virus. New apps are appearing that can help, but what types of apps are best—and which are safe?

What Is Contact Tracing?

Contact tracing is a job typically performed by public health officials who track and interview people diagnosed with contagious diseases. Through those interviews and other research, public health workers identify other people a confirmed infected person may have been in contact with and spread the disease to. The goal is to locate, isolate, and treat potentially infected individuals to prevent further spread.

How Apps Can Help

While contact tracing has been used for years and helped eradicate diseases like smallpox, it has its drawbacks. First, it would take massive amounts of public health workers trained in contact tracing to meet the current need for COVID-19. Johns Hopkins estimates 100,000 additional contact tracers are needed to supplement public health systems. Second, successful contact tracing relies on truthful, voluntary statements from infected individuals about where they have gone and who they have been in contact with, and how well they are able to remember their interactions.

Apps are being investigated to help authorities conduct contact tracing during the COVID-19 pandemic for a number of reasons:

  • To make data collection more efficient
  • To reduce the burden of data collection on public health workers
  • To reduce exposure of public health workers to the virus
  • To use Bluetooth, GPS, or other location data to identify community contacts rather than rely only on self-reporting

There is a broad range of technology for contact tracing, and U.S. officials are still evaluating a variety of tools. Some of these tools rely on self-reported symptom data and voluntary participation, while others use proximity-sensing technology and require community-wide adoption.

The goal of contact tracing apps is to track people with either a COVID-19 diagnosis or COVID-19 symptoms and then find out who they came into contact with. Apps can notify you when someone you were in close proximity to is diagnosed with COVID-19 or develops symptoms.

How Contact Tracing Apps Work

While contact tracing apps take the guesswork out of identifying where people were and when, they still rely on people manually entering information about their condition and the onset of any COVID-19 symptoms. Here's a basic idea of how contact tracing apps work:

  1. Users download the app. Bluetooth must be turned on and left on.
  2. Phones with the app can exchange anonymous keycodes when they're within a close range.
  3. If a user develops COVID-19-like symptoms, they'll log them in the app and answer any related questions. They will also log when and if they are diagnosed with COVID-19.
  4. Anyone who came into close contact with this person within the last two weeks will be alerted of potential COVID-19 exposure.
Ellen Lindner / Verywell

Types of Contact Tracing Apps

The two main models being investigated each use a digital signal that is activated when smartphone users are near each other as described above. The big difference between these models is how data is stored and shared.

Centralized models

In a centralized contact tracing model, both the phone keycode of the app user who indicates they're COVID-19-positive and the keycodes of app users they've interacted with are uploaded to a remote server. An algorithm helps determine which of their contacts are most at-risk and sends an alert.

While the server should, in theory, keep data secure, centralized models pose privacy risks.

Examples of this type of app include the TraceTogether app used in Singapore and the CovidSafe app in Australia.

Decentralized models

Decentralized models do not store personal information. Users must choose whether or not to share data with a server. Their health, location, and interaction data is stored on their own phone.

This method gives people control over their own data, increasing privacy but decreasing the app's efficiency as a large-scale tracing tool.

Developers like Apple and Google are focusing on decentralized options for contact tracing apps.

How Are Apps Currently Being Used?

Right now, the goal of contact tracing apps in the U.S. is to track virus spread and identify clusters of outbreaks. In most areas, participation is voluntary.

While contact tracing through technology is a goal of the Centers for Disease Control and Prevention (CDC), there is no national standard or approach right now. A number of companies are developing apps, and states across the country are working with developers to create their own tracing apps. However, for contact tracing apps to be the most successful, widespread use is necessary. And that's something that won't happen until people feel confident about the security of those apps.

Privacy Concerns

Since contact tracing apps rely on technology that can track people's movements and interactions, there are naturally some concerns about privacy and confidentiality. Unfortunately, there are also examples of privacy breaches.

Privacy software company Jumbo recently reviewed North Dakota's contact tracking app, Care19, developed by a company called ProudCrowd. Jumbo found the app transferred data to Foursquare, a location tracker used extensively by marketers. The report prompted the app developer to change the app's data-sharing practices, but the damage may already have been done.

In China, apps that use location trackers and data mining collect data from people involuntarily, and they don't stop at contact tracing. These apps collect identifiers, health information, and even payment data to see who is breaking quarantine orders. Apps in other countries like Iran and India have also bypassed privacy requirements of other nations.

Pilot Projects in Development

While there are scores of apps being used to track the number of COVID-19 cases, reliable contact tracing apps are still few and far between.

The United Kingdom is preparing to release its new contact tracing app nationwide after a trial in a small population on the U.K.'s Isle of Wright. The real-time contact tracing app tracks symptoms and is intended to predict possible infections.

Researchers warn, however, that the app relies on self-reported data and could overestimate the number of actual COVID-19 cases.

Many countries have been waiting for collaboration with Apple and Google on apps that are optimized to work with various smartphone platforms in what's being called the Apple-Google model. The tech giants have held off working with some developers until they agreed to a decentralized model where user information remains more private and is not shared on a central server.

What This Means For You

Efforts to fight COVID-19 with technology are only beginning. Pay close attention to apps you are using and how your data is being shared, stored, and used.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Watson C, Cicero A, Blumenstock J, Fraser M. A National Plan to Enable Comprehensive COVID-19 Case Finding and Contact Tracing in the US. Johns Hopkins Bloomberg School of Public Health.

  2. Fuchs A, Bender R. Would COVID-19 digital contact tracing programs violate the Fourth Amendment? University of Pennsylvania Carey School of Law Center for Ethics and the Rule of Law.

  3. Centers for Disease Control and Prevention. Digital Contact Tracing Tools for COVID 19.

  4. Duball J. Centralized vs. decentralized: EU's contact tracing privacy conundrum. International Association of Privacy Professionals.

  5. Google. Exposure Notification API launches to support public health agencies.

  6. Valade P. Jumbo Privacy Review: North Dakota's Contact Tracing App.

  7. O'Neill PH, Ryan-Mosley T, Johnson B. COVID Tracing Tracker. MIT Technology Review.

  8. National Health Service. Covid 19 app support. (n.d.)

  9. Menni C, et al. Real-time tracking of self-reported symptoms to predict potential COVID-19. Nature Medicine.

  10. Google. Privacy-Preserving Contact Tracing. (n.d.)

By Rachael Zimlich, BSN, RN
Rachael is a freelance healthcare writer and critical care nurse based near Cleveland, Ohio.