Digital Contact Tracing

Last Reviewed
December 24, 2020

Digital Contact Tracing

As the entire world anticipates the end of the COVID-19 disease pandemic, everyone is learning the new, socially-invasive term 'digital contact tracing.' These government-sponsored programs may impact their lives for years to come. 

Contact tracing refers to the method that has been used to control contagious disease outbreaks for decades. A disease outbreak investigation begins when an individual is identified as having a communicable disease, says the U.S. CDC. 

Contact tracing investigators interviewed the patient, family members, healthcare providers, and anyone who may know the primary patient's contacts, anyone who might have been exposed, and anyone who might have been the source of the disease. 

To identify and quarantine contacts early enough to prevent additional transmission, case investigations should be conducted as close to the infected person’s test date and symptom onset as possible. People testing positive for or diagnosed with COVID-19 (cases) within the past 6 days should be given the highest priority for a case investigation interview.

If more than 14 days have elapsed since specimen collection, case investigation and contact tracing should not be pursued unless there are unique circumstances associated with the person tested, says the CDC.

Previously, non-digital contact tracing of coronavirus cases was essential to control disease outbreaks, said the CDC in May 2005.

The key to controlling any outbreak is the prompt detection of the infected person's contacts. Once identified, those 'close-contacts' are then subjected to 'control measures.'

Digital Contact Tracing

During the 2020 SARS-CoV-2 pandemic, digital contact tracing technologies offer innovative tactics to deploy case-finding and containment efforts.

On May 1, 2020, the U.S. CDC published an outline detailing the critical features for digital contact tracing apps and cites the “PACT protocol” as an example of the recommended method for using “Bluetooth enabled proximity tracking” while maintaining privacy. 

On June 5, 2020, the U.S. CDC published 'A Contact Tracer's Guide for COVID-19.' The interaction goals are to inform the person they may have been exposed to COVID-19, assess their medical condition and other risk factors, and gather information for continued monitoring and support. 

On June 16, 2020, The Lancet published a new study regarding contact tracing tactic effectiveness. Kucharski and colleagues looked at manual contact tracing with self-isolation, which reduced virus transmission by 57%, and app-based tracing with 53% uptake, which improved when combined with manual tracing.

On September 1, 2020, Google said, 'Technology can support and augment these efforts by allowing public health authorities to quickly notify people who may have been exposed to a person who has contracted COVID-19, including those the person might not know directly.'

The COVID Alert NJ and COVID Alert NY apps were announced on October 1, 2020, which notify users of potential COVID-19 exposure while maintaining user privacy and security. New Jersey and New York join Pennsylvania and Delaware in creating a regional COVID Alert app network that operates across state lines to stop the spread of COVID-19. Connecticut has also announced it will launch an app shortly using the same technology.

On October 12, 2020, IBM Watson Health launched a digital blockchain app so individuals can prevent verifiable health status such as COVID-19 test results from gaining access to various public locations. The app, IBM Digital Health Pass, allows individuals to store, manage, and share their mobile devices' health status.

MIT researchers announced on October 29, 2020, they have now found that asymptomatic people may differ from healthy individuals in the way they cough. These differences are not decipherable to the human ear. But it turns out that they can be picked up by artificial intelligence. The MIT team reports an AI model that distinguishes asymptomatic people from healthy individuals through forced-cough recordings, which people voluntarily submitted through web browsers and devices such as cellphones and laptops.

Another study found that a combination of symptom and sensor data resulted in an area under the curve (AUC) of 0.80 (interquartile range for discriminating between symptomatic individuals who were positive or negative for COVID-19, a performance that is significantly better than a model that considers symptoms alone. Such continuous passively captured data may be complementary to virus testing.

Using retrospective smartwatch data, a new study published by Nature on November 18, 2020, showed that 63% of the COVID-19 cases could have been detected before symptom onset in real-time via a two-tiered warning system based on the occurrence of extreme elevations in resting heart rate relative to the individual baseline.

Digital Exposure Notification System

Google says, 'Public health authorities worldwide are building apps that use the Exposure Notifications System to help their contact tracing efforts. You can find the app for your area (if available) in your app store. Once you are opt-in to the notification system, the Exposure Notifications System will generate a random ID for your device. To help ensure these random IDs can’t be used to identify you or your location, they change every 10-20 minutes.

Your phone and the phones around you will work in the background to exchange these privacy-preserving random IDs via Bluetooth. You do not need to have the app open for this process to take place. Your phone periodically checks all the random IDs associated with positive COVID-19 cases against its own list.

If there’s a match, the app will notify you with further instructions from your public health authority on how to keep you and the people around you safe.

On December 10, 2020, California became the biggest U.S. state to take advantage of new technology from smartphone software makers Apple Inc and Alphabet Inc’s Google. People in California can download the CA Notify App in the Google Play store on Android devices.

The CDC's Contact Tracer's Guide for COVID-19

A successful notification of exposure allows for an exchange of information with the person (contact) exposed to COVID-19. It offers an opportunity to answer questions and provide referrals for testing, medical evaluation, and other necessary support services. This interaction aims to inform the person that they may have been exposed to COVID-19, assess their medical condition and other risk factors, and gather information for continued monitoring and support, says the U.S. CDC.

Why Prioritize Household Contacts?

Household transmission of SARS-CoV-2 is common. Most close contact exposures are with family members and other household contacts. A prospective study found that transmission rates of SARS-CoV-2 and secondary infections among household members were higher than previously reported, at 53 percent. Another study suggests that extended family gatherings (e.g., funeral, birthday party) may also facilitate the transmission of SARS-CoV-2. Extensive transmission is a particular concern in households living in close quarters, where multiple people share the same rooms and bathrooms, and multigenerational households, say the CDC.

When at crisis levels, household contacts may be the easiest among high-risk contacts to reach. Even when case levels decrease, household contacts will remain at high risk for acquisition of COVID-19.  For prioritization purposes, household contacts include those who live with, provide care for, or visit the person diagnosed with COVID-19.

Contact Tracing Fraud

In the USA, the Department of Justice, the Department of Health and Human Services, and the Federal Trade Commission are partnering to alert the public of emerging threats to steal money and sensitive information through contact tracing scams. Contact tracing scams often appear in the form of text messages or telephone calls seeking money, or Social Security, bank account, or credit card numbers, along with other sensitive information not required for authentic contact tracing.

“As cities and states start to reopen for business and implement contact tracing measures in their reopening plans, the Department of Justice remains committed to preventing, prosecuting, and punishing rogue actors who seek to exploit these safety efforts and who attempt to steal money and sensitive information from citizens,” said Deputy Attorney General Jeffrey A. Rosen, on June 30, 2020.

Previously, on June 5, 2020, when the US Better Business Bureau issued suggestions on 'How to tell a real contact-tracer from a scam.'

And on May 19, 2020, Colleen Tressler, Consumer Education Specialist, FTC, offered several steps people can take to protect themselves from contact tracing text scammers.

Contact Tracing Immunity Passports

According to the WHO on April 24, 2020, 'Some governments have suggested that the detection of antibodies to the SARS-CoV-2, the virus that causes COVID-19, could serve as the basis for an “immunity passport” or “risk-free certificate” that would enable individuals to travel or to return to work assuming that they are protected against re-infection.'

'There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.'

Contact Tracing Programs

In the USA, the Johns Hopkins Bloomberg School for Public Health published the 'A National Plan to Enable Comprehensive COVID-19 Case Finding and Contact Tracing in the US' on April 10, 2020. This plan concludes by saying, 'Now is the time for the U.S. Congress, the administration, and the country to come together to fund ($3.6 billion) adequately and implement contact tracing at this required scale.'

'The goal of adding at least 100,000 new contact tracers in the United States and managing their work, while challenging, is achievable with appropriate financial support and a collective commitment.'

The WHO issued interim guidelines on May 10, 2020, which includes suggestions of contacts cannot be reached, and the contact tracing team should ask relatives and friends or explore other means to find them. If contacts relocate to known locations in the same catchment area, the contact tracing team should visit them. If contacts move to another catchment area, the contact tracing team responsible for that catchment areas should be informed and follow up. 

The WHO says the monitoring phase ends 14 days after the contact last came into contact with the COVID-19 patient, or if the contact develops COVID-19. If contacts are near each other, such as being in the same household, and one of them becomes a COVID-19 case, the follow-up period is reset to 14 days after the last exposure to the new case.

In a recent statement, the European Commission said 'that app usage should be voluntary and not involve any data that pinpoint people’s location.' 

Digital Contact Tracing Example

  • An example is the Republic of Singapore. To mitigate disease outbreaks, SGUnited, GovTech, and the Ministry of Health have come up with a way for Singaporeans to track close contacts should the need arise – through a simple mobile app. Using Bluetooth, TraceTogether identifies other nearby phones with the app installed. It then tracks when you are close to these other persons, including timestamps. If the need arises, this information can then be used to identify close contacts based on the proximity and duration of an encounter between the two users.
  • Singapore's Prime Minister’s Office announced on September 11, 2020, that the Government would begin nation-wide distribution of TraceTogether (TT) Tokens at communities with higher concentrations of the elderly. It consists of the TT app on smartphones and the physical TT Token, with both services based on individuals’ SafeEntry records. This Self-Check service and SMS service alerts people if they have visited the same venues simultaneously as COVID-19 cases.

  • The TT program is Singapore’s national-level initiative to supplement contact tracing efforts to reduce the community spread of COVID-19. Anyone entering a public venue in Singapore is required to scan a QR code or their identity cards upon entry to a public place.

Contact Tracing Privacy Laws

Privacy advocates fear that governments 'will take away personal liberties in the name of fighting COVID-19 and will never give them back.' In the USA, the HIPPA Law was passed in September 1996, which initiated national standards for various health information uses.

When the Department of Health and Human Services Commissioner declared a public health emergency on January 31, 2020, he also exercised his authority, effective March 15, 2020, to waive sanctions and penalties against a covered hospital that does not comply with certain provisions of the HIPAA Privacy Rule. This rule change has led to substantial confusion amongst privacy groups.

In light of privacy concerns, Google and Apple announced on May 4, 2020, to ban GPS location data from contact-tracing apps that rely on their technology. On April 4, the companies said they would not allow the use of GPS location data in conjunction with their new Bluetooth contact-tracing system. In effect, this decision forces states to choose between tracking encounters using Bluetooth or collecting location data.

On April 21, 2020, the European Data Protection Board (EDPB) adopted guidelines on the processing of health data for research purposes in the context of the COVID-19 outbreak and guidelines on geolocation and other tracing tools COVID-19 outbreak.

These EDPB guidelines on the processing of health data for research purposes in the context of the COVID-19 outbreak aim to shed light on the most urgent legal questions concerning the use of health data, such as the legal basis of processing, further processing of health data for scientific research, the implementation of adequate safeguards and the exercise of data subject rights.

Digital Contact Tracing Market Research

On June 15, 2020, when asked if they planned to download a contact-tracing app, an overwhelming majority — 71% — answered no. The data was gathered from an online survey of just over 2,000 people in the USA, collected on June 1, 2020, by polling company Opinion Matters. The most common reason cited was a concern about privacy; 44% of those who said "no" to a contact-tracing app said they would not trust the technology to protect their digital privacy. And, 39% also said they thought the apps created a false sense of security.

On May 26, 2020, a new analysis of 50 COVID-19-related apps, including their use and access to personally identifiable information, ensures that the right to privacy and civil liberties are protected. A troubling discovery in this Nature report is that only 16 of the 50 apps indicate that the user’s data will be made anonymous, encrypted, and secured and transmitted online and reported only in an aggregated format. 

On May 19, 2020, an Ipsos poll in the USA found 76% of people would give coronavirus contact tracing officials a list of all the people they had recently come into contact with. However, only 56% would access their cell phone location data for tracing systems established by public health officials.

As of April 23, 2020, Kaiser Health Tracking Poll finds the US public is divided on whether they would be willing to download an app for these purposes. Overall, most of the public (68%) are willing to use an app on their phone to share results from a coronavirus test to allow public health officials to track the outbreak's spread. Majorities across age groups and party identification say they are willing to use an app for these purposes.


Note:  This content has been aggregated from various sources, such as the CDC, WHO, The Lancet, and various media reports by Donald Hackett, who has been following health privacy laws since 1992.