COVID-19 Contact-Tracing Apps

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COVID-19 contact tracing apps are digital platforms designed to help identify and prevent the spread of COVID-19. Their purpose is to automate the contact tracing process in a faster and more reliable way. These mobile applications are not intended to replace existing contact tracing methods, but rather to act as additional support.

Smartphones have been identified as useful devices for contact tracing because of their GPS and Bluetooth capabilities. Additionally, the wide use of smartphones globally has created a relatively accessible way for COVID-19 contact tracing apps to collect data from their users. This data is then used to help identify people who have been exposed to and possibly infected with COVID-19.[1]

With mobile applications increasingly becoming important tools for combating the spread of the COVID-19 virus, several ethical concerns have been identified and discussed. Challenges regarding privacy, equity, voluntariness, and accuracy have grown common, as these applications rely heavily on user data. However, research has shown that if in line with ethical guidelines, COVID-19 contact tracing apps may serve as an effective tool.

Coronavirus Disease 2019

Coronavirus disease 2019 (COVID-19) is a disease caused by the SARS-CoV-2 virus. It was first discovered in Wuhan, China in late 2019 and has since spread worldwide, resulting in an ongoing pandemic. As of mid-January 2022, there have been over 350 million confirmed COVID-19 cases worldwide and over 5.5 million reported deaths.[2]

According to the CDC, COVID-19 is very contagious because it is a respiratory virus. This means that it can be quickly transmitted when an infected person breathes, coughs, sneezes, or speaks out droplets that contain the virus. Anyone within 6 feet of an infected individual is at risk of becoming infected.[3]

Symptoms of COVID-19 have been reported to include a wide range, varying from mild to severe illness. People may begin to experience symptoms anywhere between 1-14 days after initial exposure. These symptoms can include a fever, cough, shortness of breath, fatigue, loss of taste or smell, congestion, and a sore throat. Older populations, as well as those with underlying health conditions, are reported to be at higher risk for developing more severe symptoms of COVID-19.[4] Asymptomatic cases have also been found to be very common among patients, creating further challenges for the pandemic. In a recent study conducted by Duke University, nearly 40% of the children aged 6 to 13 who tested positive for COVID-19 were asymptomatic.[5] As a result, many infected individuals can spread the virus without ever knowing it.

Overall, it has become difficult to manage positive COVID-19 cases due to the large range of symptoms and the ease of spread. In response, public health officials have employed several methods, such as contact tracing, to help mitigate the spread of the disease and protect communities.

Contact Tracing

Contact tracing is a method that has long been used by health departments to minimize contagious diseases. The process aims to identify both the individuals infected as well as the people they have been in close contact with to prevent further spread.[6] The basic process of all contact tracing follows four steps: testing, identification, notification, and monitoring.[7] This process is generally initiated when an individual begins showing symptoms of a given disease or is known to have been exposed to it. Testing is the first step of contact tracing because it can confirm if one is infected. The type of tests used varies based on the disease for which one is screening. Tests can include blood tests, urine tests, throat swabs, nasal swabs, and spinal taps.[8] Once an individual is confirmed to be infected, they need to identify everyone that they were in close contact with during the period of their contagion. In certain cases, they can include the time before they began experiencing symptoms. All contacts are then notified of the details of their exposure and advised on how they should proceed. They are also often provided resources for how they can protect themselves. Close contacts are will be followed up with to help monitor their health. Depending on the circumstance, they are encouraged to self-quarantine if possible and to track any symptoms for a specific time period. Contact tracing has proven to be successful in other worldwide events, such as the Ebola epidemic and the HIV pandemic.

The Role of Contact Tracing in Response to COVID-19

Contact tracing has become a cornerstone of various public health departments’ responses to the COVID-19 pandemic. Countries have implemented large-scale contact tracing efforts in hopes of decreasing the spread of the COVID-19 virus and helping protect their local communities. In the context of COVID-19, a close contact is considered to be “someone who had face-to-face contact with an infected person within 6 feet for at least 15 minutes.”[9]

Manual Contact Tracing

Traditionally, contact tracing has been done manually by individual public health officials. When a patient is confirmed to be infected, they will be contacted by the health department to complete an interview with a member of their staff. The staff member will then be responsible for notifying those who have been exposed as quickly as possible as well as following up with them periodically. These interviews are generally conducted over the phone one at a time.[10]

Although manual contact tracing has previously proven to be effective, recent studies have suggested that the procedure may be limited in the face of the COVID-19 pandemic. Delays in testing have complicated contact tracing methods, making it challenging for health systems to keep up.[11] According to a study done in the UK, manual systems of contact tracing are likely to be more and more overwhelmed as infection rates increase.[12] This is due to several reasons, beginning with the fact that manual contact tracing procedures rely on a sizable trained workforce.[13] Manual contact tracing is also very labor-intensive and can move very slowly. This method is also limited because it requires infected individuals to cooperate throughout the full interview process. Those who have tested positive may not always be reached and some may not know or be willing to disclose the full details of their close contacts.[14] Additionally, not all people are symptomatic, leaving many positive COVID-19 cases undetected and therefore, untraced.

Expanding to Digital Contact Tracing

Researchers quickly began exploring technology-based solutions to increase the scale of contact tracing for COVID-19. With the use of Bluetooth and GPS technology, digital applications have created automated methods of contact tracing. A study conducted by Jonatan Almagor and Stefano Picascia explored the effectiveness of a COVID-19 contact tracing app compared to that of manual methods. When the user of the contact tracing app tested positive for COVID-19, their smartphone notified those who had come into close contact of their potential exposure. The research found that smartphone-based contact tracing was a mitigation strategy worth pursuing, as it not only reduced the spread of the virus but also did so at a faster and more affordable rate than it would have been if done manually.[15]

Kinexon also pursued a digital solution for contact tracing through the creation of their SafeTag. Both the wearable device and application “warns users if they are too close to another” in addition to recording the proximity and duration of their exposures.[16] Kinexon’s SafeTags are currently being used by large companies to perform real-time contact tracing to help prevent the spread of COVID-19 within their facilities. The NBA and NFL have used the device as part of their procedures to keep players, officials, coaches, and employees safe.[17]

Digital contact tracing methods also have limitations due to several different reasons. To start, the effectiveness of a digital solution largely relies on the installation rate in the given area. A study done on Singapore’s app confirmed this when only 20% of the population used the app. The results stated that only 4% of the exposed contacts would have been able to be contacted through the app because of the low participation. The study said that digital contact tracing methods become less effective when people are unable to or unwilling to engage with them.[18] Digital contact tracing methods are also limited when people do not know how to properly use them. A study conducted on a Japanese COVID-19 contact tracing app said that “only 60.8% of users were using the application correctly.”[19] As a result, this limited the capabilities of the tool.

Overall, digital contact tracing has been found to effectively support COVID-19 mitigation efforts. However, it is critical that users actually download, register, and actively use it.

App Structures

Structures for COVID-19 contact tracing apps. Picture taken from BBC.

As various COVID-19 contact tracing apps have been developed, two structure types have emerged. Applications follow either a centralized or decentralized model. These structures primarily differ in their storage methods as well as their data collection processes.

Centralized Structure

A centralized contact tracing app collects and stores data through a central server owned and operated by government bodies, such as public health departments. All data gathered is anonymized before being uploaded. The server processes the data received and informs necessary users about their exposures.[20]

Examples of Centralized Apps

TraceTogether is a mobile application used in Singapore aimed to minimize the spread of COVID-19. The platform uses Bluetooth to determine when other users are nearby and notifies them if they have been exposed to the virus. TraceTogether was one of the very first COVID-19 contact tracing applications to be launched and was installed by 20 percent of Singapore’s population after just one month.[21] The application attracted the interest of many other governments looking to adopt similar tools.

Decentralized Structure

A decentralized contact tracing app stores user data on their personal devices, such as a mobile phone, which will then alert them when they are at risk for infection.[22] This structure gives users more privacy by allowing them to have full control over their information [23] Additionally, their data is not accessible to government bodies.

Examples of Decentralized Apps

Apple and Google have partnered together to develop the Exposure Notification System that is available for all Android and iOS devices. The purpose of the technology is to aid governments in the protection of local communities against the spread of COVID-19. The Exposure Notification System relies on Bluetooth technology to track exposures and alert users when necessary.[24] MI COVID Alert is a COVID-19 exposure notification application developed by the Michigan Department of Health and Human Services (MDHHS). The platform uses Bluetooth Low Energy (BLE) in collaboration with Apple and Google’s API to notify Michigan residents of COVID-19 exposures. This application is completely voluntary and prioritizes the protection of users’ privacy and data.[25] COVIDSafe is the Australian Government’s coronavirus app released on April 26, 2020. The application uses Bluetooth technology to anonymously take note of other app users people come in contact with. COVIDSafe keeps all data encrypted and stored locally on each users’ device. When exposed, users will be notified with steps on how to stay safe. COVIDSafe has over 7 million registered users.[26] HaMagen is Israel’s contact tracing app supported by the Ministry of Health. The application uses the GPS history of users’ phones and cross-checks it with the geographic data of COVID-19 patients from the Ministry of Health. In the event of a match, HaMagen will send users resources on how to stay safe. The application has remained transparent with users by using an open-source code.[27] Covid Watch is the exposure notification application for the state of Arizona. The application is a privately owned platform developed by WeHealth. It was an early adopter of the Google Apple Exposure Notification API and continues to work with both companies to ensure users’ data remains protected. Covid Watch was proven to be successful after the University of Arizona saw a nearly 11% reduction rate on campus.[28] The university had included Covid Watch as part of its campus safety protocols.

Best Practices: Preempting Ethical Issues

With the rise of Covid-19 contact tracing apps, various institutions have released general guidelines for the ideal platform. These suggestions are intended to preempt applications from being designed unethically.

Decentralized Privacy Protocol

The University of Michigan Center for Ethics, Society, and Computing recommends that all COVID-19 contact tracing applications should follow a decentralized structure to minimize chances for mistreatment or data breaches.[29]

Anonymized Data

The University of Michigan Center for Ethics, Society, and Computing recommends that all data collected should be left anonymous to protect the privacy of users. Such data, including health and location, should be disassociated with any personally identifiable information.[30]


According to Jeffrey Kahn, director of the Johns Hopkins Berman Institute of Bioethics, “policies should make sure that access to the technology and its benefits, as well as the distribution of its burdens, are shared equitably.”[31] Since digital contact tracing has been proven to offer a benefit, a COVID-19 contact tracing app must be accessible for everyone within its targeted population.


A study published by JMIR mHealthAll suggests that all steps of an application should be voluntary and consent-based. The application should maintain full transparency with users by making information about data use, protection, and privacy publicly available.[32] Users should also always have the ability to opt-out of participation at any time without consequence.


According to the World Health Organization (WHO), all “algorithmic models used to process data and assess risk of transmission must be reliable, verified and validated.”[33] These models should also be tested by third parties prior to being made available to the public in order to make necessary improvements. Additionally, it is essential that all algorithms and data collection processes are closely reviewed in order to mitigate the potential for biases.[34]

Post-Pandemic Protocol

The University of Michigan Center for Ethics, Society, and Computing recommends that once the COVID-19 pandemic has been declared to be over, all data should be destroyed. Details about this process should be made clear to users so that they can confirm their data will not be used for any other purpose. This applies to both centralized and decentralized applications, meaning that information should be erased from local devices as well as government-controlled storage.[35] Users should also be given instructions on how to delete the application from their personal devices.

Ethical Concerns

Although COVID-19 contact tracing apps have proven to be effective, there are still some ethical concerns that have prevented a high degree of adoption.


The emergence of COVID-19 contact tracing apps has created issues surrounding users’ privacy. These applications require a certain amount of user data, such as location, to accurately track COVID-19 exposures. Many people are not accustomed to having their personal information tracked, especially if they do not know exactly how it will be used. Users have found that many applications have vague privacy and data management policies. In some cases, applications do not share them at all.[36]

Privacy issues particularly concern centralized COVID-19 contact tracing applications because this structure allows governing bodies to access personal information about all of its users. As a result, it can become less clear who has access to users' data. Centralized apps are also at a higher risk of a data breach, as hackers or other individuals may try to gain control of the data.[37] In the event of a breach, a large population will be at risk of having their data exposed.


Equity is an ethical concern in regards to COVID-19 contact tracing apps because the required technology is not available to everyone. Although the use of mobile phones has spread rapidly around the world, there are still disparities between those who do and do not have access to tools such as the internet and GPS or Bluetooth-capable devices. A study conducted by Pew Research Center found that smartphone ownership was higher in places with advanced economies than emerging. Additionally, those with higher education, whether in advanced or emerging economies, were also more likely to have access to mobile devices.[38] As a result, there are concerns that COVID-19 contact tracing apps will disproportionately benefit certain populations.


Voluntariness is an ethical concern in the context of COVID-19 contact tracing apps, specifically when it is not protected. Voluntariness can be defined as a decision or action made free from coercion or influence by outside parties.[39] An application that protects voluntariness makes each step of the digital contact tracing process voluntary. This includes the user’s decision to download the application, enroll in alerts, and share contacts after testing positive.[40] Voluntariness also requires that adequate information is provided to the user about the application so that they can make well-informed decisions.

As discussed above, the success of a COVID-19 contact tracing app heavily relies on the population's participation. Ideally, a public health department could require everyone with a personal device to download and register for a given app so that their data could be tracked. However, this greatly imposes on one's autonomy.[41]


Another concern that has been raised about COVID-19 contact tracing apps is their accuracy. When someone is found to be exposed to the disease, they will need access to the correct resources to remain safe. They will also need to be able to receive appropriate medical care if necessary. However, these resources are not always available, especially in areas with large outbreaks. Thus, there are concerns that a faulty contact tracing app will result in these resources going towards someone who was falsely identified, rather than those who are actually infected or have actually been exposed.

In addition to one’s health, COVID-19 can also affect the ways in which one can interact with others. An exposure generally forces someone to change their daily routine and can cause additional challenges to their employment or education.[42] This may result in a loss of income or an increased level of stress. This creates concerns about digital applications because an inaccurate notification can quickly disrupt and hinder many people’s lives.


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