The Current Stage of COVID Contact Tracing in the US
Contact tracing is an important part of curbing the spread of COVID-19. Getting as many contacts of an infected person traced and quarantined promptly can curb transmissions of the disease. Not only can good contact tracing significantly reduce transmissions, but it is also essential to the reopening of economies.
This paper has pointed out that getting as many contacts traced for a highly contagious disease such as COVID-19 is especially important in lowering R, also known as the “effective reproduction number”. In other words, to reduce the infections caused by the carrier of the coronavirus, hence lowering the spread, one needs to track down as many contacts as possible. For COVID-19, which has R0 (the basic reproductive number) of around 3.5, an above 90% contact tracing rate within one day of case discovery is needed to get R below 1, thus slowing down the spread.
This blog post will look at current technologies and scales employed in contact tracing in the US and discuss what authorities can do to better conduct contact tracing.
Technologies used in contact tracing
The most fundamental form of contact tracing conducted is through interviews of the infected individuals. These interviews require good techniques as the interview subjects are usually sick and these interviews would involve sensitive information. Even with well-trained contact tracing investigators, many contacts could still be missed due to mistrust and lack of cooperation. The reality of contact tracers in the US is even less ideal. The average turnaround time of contact tracing investigations is 3 days, hence significantly reducing the effectiveness as many contacts could already be infected and spreading the disease by the end of the period. Furthermore, many tracers in the US are hired on a part-time basis, thus are less experienced in conducting interviews.
All these challenges are the reasons why governments are looking into using technologies to aid contact tracing efforts. In South Korea, for example, the government used credit card transaction history, CCTV video footage, cellular carrier data, and GPS data to better enhance the travel records of infected cases. Countries in Asia also used QR codes to passively track people’s travel histories. Apple and Google also unveiled tools using Bluetooth technology to help trace close contacts. However, these technologies have their own problems: privacy is a big concern in accessing sensitive personal information such as credit card transactions; GPS locations are often inaccurate, leading to false positives; Bluetooth technology products (such as mobile phone apps) face the issue of not being installed enough hence ineffective. This article outlines the many hurdles that technological approaches are encountering in contact tracing. It is because of these issues that governments in the US are slow to adopt these technologies, with only the first state announcing adoption through the Apple-Google Bluetooth app very recently.
Number of contact tracers matter, but states are not hiring enough
With all of the problems that innovative and technological approaches, human and investigation forms of contact tracing still remain the main force, at least in the US. The way that this would work is by hiring as many contact tracers as needed. This number is not just based on the population of a state, but also the number of new cases developed daily. Studies suggest that at least 5 to 15 contact tracers per daily positive test are needed to effectively track down contacts. This would be especially hard to achieve if a state is experiencing a surge in cases. The strain on contact tracing efforts has been evident in the recent rise in cases across the nation. Even Alaska, which has been acclaimed for its contact tracing efforts, is facing stress to its contact tracing system statewide recently.
Data from “TestandTrace”, collected through outreach to health departments and other efforts, publishes contact tracing resources data. Using its data, we can visualize whether states are hiring enough contact tracers to track contacts effectively, and if not, how many more tracers are needed.
Figure 1 shows whether a state is hiring enough contact tracers, and Figure 2 shows the gap of contact tracers across US states. Several traits are evident through these visualizations:
Most states are not hiring enough contact tracers;
Large states in the South (California, Texas, and Florida) have large gaps in the number of tracers hired, possibly attributable to the recent surge in cases straining their contact tracing systems;
The Northeast and Washington have enough contact tracers, but many of these states do not have much more wiggle room to trace another wave of cases;
Figure 3 depicts whether states’ planned number of contact tracers would be enough to track cases at the current level, and the situation is not very different from the current numbers depicted, except Alaska and New Jersey.
There is hope — the importance of open access to information
The situation of contact tracing might be less than ideal in the US as many states are not hiring enough tracers, but open-information initiatives such as TestdandTrace provide incentives for governments to increase capacity. When NPR first released their contact tracing data back in April, states nearly doubled plans for contact tracers after the first survey. NPR’s updated contact tracing information, and George Washington University’s Contact Tracing Workforce Estimator are also good sources to aid public policy decisions. The openness of information has been a unique trait of the research on this pandemic in the US. The availability and detail of the data, including ones visualized in our COVID Atlas project, is beneficial to authorities and could help them better address the pandemic.
- Ryan Wang is a Spatial Data Science Summer Fellow at University of Chicago.
- TestandTrace: the datasource that is cited in this article that focuses on tracking states’ testing and contact tracing resources.
- A great blog about testing and contact tracing where part of the ideas for this article comes from.
