Elderly woman undergoing contact tracing efforts

Contact tracing: What organizations need to know about digital and manual approaches

Organizations, both private and public, should consider adopting a program that includes elements of both digital and manual contact tracing.

According to the Centers for Disease Control and Prevention (CDC), contact tracing is a series of steps taken to identify, monitor and support contacts who have been potentially exposed to an infectious disease. The effectiveness of contact tracing for reducing the transmission and spread of viral diseases like COVID-19 is well-established. Multiple studies have confirmed the benefits of this public-health practice for controlling viral outbreaks, including SARS, Ebola and Monkeypox1-4.

Contact tracing, as an infectious disease control strategy, is most frequently managed by government public health agencies, but all organizations, large and small, private or public, should consider supplementing government efforts with their own contact tracing activities. An effective contact tracing program can provide many benefits to organizations.

First and foremost, when aligned with state and local health departments, contributing to contact tracing efforts has a direct impact on public health. Organizations that undertake appropriate elements of contact tracing could potentially help reduce strain on local public health as well as support government and community efforts to reduce transmission of COVID-19.

For employers, contact tracing is being considered by many companies for their business continuity and resiliency plans.

A recent survey of c-suite executives found that almost 74% of respondents believe contact tracing is an essential part of their plans.

Having a contact tracing program in place could help employers mitigate the spread of infection, maintain productivity and prevent costly shutdowns. Taking the necessary steps to protect a workforce can build trust with employees and make them feel more confident in returning to work. Additionally, these measures can help protect employees and avert on-site outbreaks, which can ultimately lead to workplace shutdowns, and reputational damage.

For universities and schools, a contact tracing program could be an important tool for bringing students back to campus. An effective program could help mitigate the spread of infection on campus, contain small outbreaks and ultimately help campuses stay open. In return, universities could see less of an impact on enrollment, and increase student and parent confidence in the value of their education. Faculty and staff would also be more likely to support in-person teaching if a strong and transparent contact tracing program was established.

Determining what type of contact tracing program an organization should pursue depends on many factors, but most organizations would benefit from a hybrid approach.


1. Contact Tracing: Frequently Asked Questions, CDC.gov, retrieved Dec 10, 2020
2. Kwok KO, Tang A, Wei VWI, Park WH, Yeoh EK, Riley S. Epidemic Models of Contact Tracing: Systematic Review of Transmission Studies of Severe Acute Respiratory Syndrome and Middle East Respiratory Syndrome. Comput Struct Biotechnol J. 2019;17:186-194.
3. Silenou BC, Tom-Aba D, Adeoye O, et al. Use of Surveillance Outbreak Response Management and Analysis System for Human Monkeypox Outbreak, Nigeria, 2017-2019. Emerg Infect Dis. 2020;26(2):345-349.
4. Swanson KC, Altare C, Wesseh CS, et al. Contact tracing performance during the Ebola epidemic in Liberia, 2014-2015. PLoS Negl Trop Dis. 2018;12(9):e0006762
5. "C-Suite Buyer Survey: Return to Work IT Solutions", BCG, July 2020

Manual vs. digital contact tracing

The next evolution in contact tracing is happening now. Technology has strong potential for helping to mitigate COVID-19 transmission, but there are limits to how much it can help.

Traditional, or manual, contact tracing involves teams of investigators conducting interviews with infected individuals to learn who they had contact with recently and subsequently reaching out to those contacts to inform them about their exposure.

Digital contact tracing involves using electronic data to identify potential exposures to infection. This data can be collected through a variety of technologies, including GPS, Bluetooth, wi-fi sensors, cell phone networks and wearable devices, then cross-referenced to determine who may have been near someone who tested positive for COVID-19. People within a certain distance of the infected person could then be automatically notified and encouraged to get tested or self-isolate.

With technology being more ubiquitous and cost-effective and fast, governments and public health programs have eagerly attempted to use digital contact tracing techniques as a part of their efforts to combat COVID-195. Yet many of these programs are revealing the limits of digital approaches.

One of the more challenging limits to overcome is participation. For digital contact tracing to be effective, a certain percentage of people in a community needs to participate. Experts disagree about what that percentage is and it depends on a number of factors, such as testing rate and community infection rate as well as compliance with quarantine. Some argue that adoption needs to be as high as 50% or 60% while others suggest lower numbers could be helpful6. Yet achieving effective adoption rates can be difficult for multiple reasons.

Female utilizing digital contact tracing app on her phone

First, people need to have access to a smartphone or another compatible device. That automatically eliminates certain populations from participation, including traditionalist communities, indigenous people, and underserved populations like the homeless. Those who do have access to a compatible device often have to download an app or take extra steps to opt into a program, which can drive a poor user experience and reduced participation. In Singapore, a country with a very strong technology infrastructure, the government had difficulty convincing people to use one of their first contact tracing apps because the detection protocol drained the batteries in a popular phone model7.

Overall, digital contact tracing might be appealing due to lower costs and scalability, but there are challenges that currently make it unfeasible for governments and organizations to rely on digital contact tracing alone. A combination of digital and traditional approaches can lead to a more effective method of contact tracing.


6. Owusu, P.N. Digital technology applications for contact tracing: the new promise for COVID-19 and beyond?. glob health res policy 5, 36 (2020). https://doi.org/10.1186/s41256-020-00164-1
7. No, coronavirus apps don’t need 60% adoption to be effective, MIT Technology Review, June 5, 2020
8. Altmann S, Milsom L, Zillessen H, Blasone R, Gerdon F, Bach R, Kreuter F, Nosenzo D, Toussaert S, Abeler J. Acceptability of App-Based Contact Tracing for COVID-19: Cross-Country Survey Study JMIR Mhealth Uhealth 2020;8(8):e19857

Manual contact tracing requires more resources

Although manual contact tracing is effective, it’s an approach that needs a lot of manpower, time and money to reduce disease transmission.

Manual contact tracing is a tried-and-true public health tool that has been used for over a century. One benefit to this approach is that manual contact tracing doesn’t require people to opt-in, so manual contact tracers can identify more potential exposures than digital contact tracing. Another major benefit of this approach is that people find speaking with a real person on the phone to be more empathetic than receiving a written notification8. A human contact tracer can also provide cultural competence and more specific recommendations when it comes to navigating difficult questions about living arrangements, transportation limits, disabilities and other sensitive topics that would be hard to address through digital contact tracing.

Having an actual person deliver the news about a COVID-19 exposure can also reduce potential panic and anxiety. Many people, especially people who are elderly or medically vulnerable, appreciate having someone who can answer questions and respond to specific concerns right away. Having that degree of support can also increase the chances that people will follow a contact tracer’s recommendations and comply with quarantine guidelines.

This approach requires a lot of resources though. Investigators need to be trained, and they need to have a certain amount of expertise. The scale of the COVID-19 pandemic also means that a lot of investigators are needed to reduce transmission. In Wuhan China, the original virus epicenter, approximately 1 trained investigator was needed for every 1,200 citizens to support the city’s re-opening9. Estimates for the number of contact tracers needed in the United States ranged from 30,000 to 300,000 depending on the size of the outbreaks that need to be contained9-11.

This form of contact tracing can be expensive because of the number of staff required and the salaries needed to attract skilled workers. One estimate suggests that the cost for a manual contact tracing workforce of 150,000 would cost USD 7.5 billion for a single year12. A workforce that large is intended to cover an entire population of 300 million. Extrapolating those results means that a high-density city with a population of 1 million would need at least 500 contract tracers at a cost of around USD 25 million, a medium-density urban area of 100,000 would need at least 50 contact tracers at a cost of USD 2.5 million and a lower-density residential community of 10,000 would need at least 5 contact tracers at a cost of USD 250,000. Most organizations would have needs on the lower end of the spectrum. But those estimates also don’t include supplies, infrastructure or other materials needed to support contact tracing, so the costs of manual contact tracing could add up real quickly.

One other hurdle for manual contact tracing is that COVID-19 spreads so fast that investigators can be quickly overwhelmed. This type of contact tracing is hard to scale, which is why research suggests that manual contact tracing should be supplemented with digital contact tracing to form a hybrid, human-centered approach.


9. The Challenges of Contact Tracing as U.S. Battles COVID-19, Pew Research Center, October 30, 2020
10. A Coordinated, National Approach to Scaling Public Health Capacity for Contact Tracing and Disease Investigation, ASTHO.org, retrieved Dec 9, 2020
11. A National Plan to Enable Comprehensive COVID-19 Case Finding and Contact Tracing in the US, Center for Health Security, April 10, 2020
12. National Covid-19 Testing Action Plan Pragmatic steps to reopen our workplaces and our communities, Rockefeller Foundation, retrieved Dec 9, 2020
13. The Promise and the Perils of Contact Tracing, BCG.com, June 12, 2020

Evidence for smart-assisted contact tracing

Both manual and digital contact tracing have limitations but there’s evidence that combining both into a hybrid form of smart-assisted contact tracing could be more effective than either approach on its own.

For most organizations, a hybrid approach called smart-assisted contact tracing would ultimately be the best. Although hybrid approaches like smart-assisted contact tracing are new and evidence is still being collected to support how effective they are, there are some early signs that smart-assisted contact tracing is a useful tool for reducing disease transmission.

One modeling study found that app-based communications could lead to people being tested and treated sooner for COVID-19 compared to manual contact tracing alone13.

Flight attendant verifying a businessman’s health credentials through a digital contact tracing app
With sufficient app participation, the addition of digital contact tracing could potentially prevent up to 80% of transmissions.

Another modeling study indicates that introducing an app or another digital contact tracing method reduces the number of manual contact tracers and COVID-19 tests that would be needed to reduce transmission14. For example, if there was an app adoption rate of 50% with some restrictions like social distancing or a mask mandate in place, then 350 manual contact tracers would be just as effective at reducing transmission as 700 manual contact tracers.

Beyond models, there has been a recent proof-of-concept study in Japan that found using a health observation app extended the reach of their investigators15. Before the app was introduced, the telephone interview process for interviewing around 70 potential exposures would take four people and more than two hours to complete. With the app, people who were potentially exposed to the virus could submit information about their health each day, such as their body temperature and symptoms, without having to find time to speak with a contact tracer over the phone. So only a single person was needed to collect all the data and conduct follow-up calls for people who needed more assistance.

In addition to phone-based apps, researchers have also found that wearable devices could be an effective contact tracing tool for facilities where people live close together like nursing homes or long-term care facilities16. They found that a system of devices worn on the wrists of residents, staff and visitors could help scale contact tracing for larger groups of people and could lead to 52% fewer cases of COVID-19 compared to traditional contact tracing methods.

Overall, evidence is accumulating that smart-assisted contact tracing would not only be more effective at reducing transmissions but could also potentially be one of the most cost-effective contact tracing methods for fast-spreading diseases like COVID-19.


14. Mirjam E Kretzschmar, Ganna Rozhnova, Martin C J Bootsma, Michiel van Boven, Janneke H H M van de Wijgert, Marc J M Bonten, Impact of delays on effectiveness of contact tracing strategies for COVID-19: a modelling study, The Lancet Public Health,Volume 5, Issue 8,2020,Pages e452-e459,ISSN 2468-2667, https://doi.org/10.1016/S2468-2667(20)30157-2.
15. Labno A, Kellar J, Lawyer P and Wroblewska J The Promise and Perils of Contact Tracing, BCG, June 12 2020.
16. Yamamoto K, Takahashi T, Urasaki M, Nagayasu Y, Shimamoto T, Tateyama Y, Matsuzaki K, Kobayashi D, Kubo S, Mito S, Abe T, Matsuura H, Iwami T Health Observation App for COVID-19 Symptom Tracking Integrated With Personal Health Records: Proof of Concept and Practical Use Study JMIR Mhealth Uhealth 2020;8(7):e19902
17. Wilmink G, Summer I, Marsyla D, Sukhu S, Grote J, Zobel G, Fillit H, Movva S Real-Time Digital Contact Tracing: Development of a System to Control COVID-19 Outbreaks in Nursing Homes and Long-Term Care Facilities JMIR Public Health Surveill 2020;6(3):e20828

Why choose smart-assisted contact tracing?

A smart-assisted contact tracing approach is one of the most effective, safe and equitable options.

By pursuing smart-assisted contact tracing, organizations would be more likely to have an effective program with fewer startup costs and potentially, a faster start. Combining the efforts of human contact tracers with digital contact-tracing technologies will give most organizations the reach they need to reduce transmission without making significant investments in hiring a temporary workforce or burdening people with frequent tests.

Although custom digital contacting tracing applications are a potential option, most organizations would benefit from engaging with an experienced software vendor that offers an out-of-the-box solution. Rather than maintaining software and hardware updates on their own, an experienced vendor can help organizations stay up to date and spread update costs across multiple clients. Fortunately, there are currently many different offerings available that can suit the needs of private and public organizations both large and small.

Overall, smart-assisted contact tracing offers organizations the best potential for a return on their investment. This approach could not only save organizations money but could also provide other types of returns. For employers, people appreciate leaders who take proactive steps to protect their health and empower them to make informed decisions. The goodwill organizations build by pursuing contact tracing could ultimately be just as important as financial resources for weathering the pandemic and emerging strong.