What Is Cellphone Contact Tracing?

Learn about this important public health tool

Cellphone contact tracing is a process where your smartphone tracks your movements, looking out for any time you've had a recent interaction with someone who has since tested positive for contagious disease or virus like COVID-19. If that happens, you're then informed of your exposure to the virus and told to self-isolate for a set amount of time so you don't spread it any further. Contact tracing apps will be made available for Android and iOS devices to make this process simpler for all smartphone users. It aims to be far more effective than conventional contact tracing.

This information primarily relates to cellphone contact tracing within the US but most of the information is relevant for other countries that are also adopting contact tracing apps.

A woman wearing a face mask walking down the street looking at her smartphone
Thomas Tolstrup, Getty Images 

What Is Cellphone Contact Tracing?

Conventional contact tracing is a highly involved process where the moment a person is diagnosed with a contagious virus, public health officials have to interview them to find out who they've been in contact with and places they may have frequented. By finding out, they can inform people that they've been at risk and those people can take appropriate action to protect themselves and others. 

It's a complex process that can take a long time to complete. On a global scale, the sheer amount of man-hours can be overwhelming and in the case of a highly contagious virus, can be too slow to be effective. 

With modern technology, it's possible to simplify that process via smartphones. 

How Does Smartphone Contact Tracing Work?

Smartphone contact tracing at its simplest works via a form of Bluetooth contact tracing. All smartphones have short range Bluetooth chips that are usually used for connecting to headphones or other wireless devices It's these Bluetooth chips that make it possible for phones near each other to communicate and detect if the owner of the phone has been diagnosed with a contagious disease.

It requires users to opt-in to the service as well as to report their symptoms or diagnosis, but the system would be entirely anonymous so no one would ever know which individual they dealt with that was infected. Once you've opted into contact tracing, your device is assigned a random digital ID which is then sent to other devices as and when needed, so the process is entirely anonymous and hands-off. 

Some countries such as South Korea also use cell phone location tracking data on top of the short wave form of Bluetooth to track users. 

How Are Google and Apple Involved in Mobile Contact Tracing?

Due to how Bluetooth normally works and communicates, Google and Apple have needed to be involved with cellphone contact tracing so that it can be achieved. Both firms have developed API systems that will allow iPhone and Android phones to use Bluetooth data between each other, thereby tracking if you've been near other people with COVID-19. 

Without the two firms' efforts to update the iOS and Android operating systems, cellphone contact tracing wouldn't be possible. Cellphone contact tracing apps need to have the information fed to them via the APIs that Google and Apple have already implemented within their phones. 

Why Might Cellphone Contact Tracing Not Work?

The big issue that could hinder cellphone contact tracing's success is whether people use it. For privacy reasons, Google and Apple has stated that governments must make contact tracing apps a voluntary/opt-in concept. Users have to choose to download the app and then choose to provide information such as whether they're exhibiting symptoms or have been diagnosed with COVID-19. Not everyone might want to do this for a variety of reasons. 

These include:

  • Privacy concerns. Some people may be concerned that the technology is invasive or that the government is able to track them through it.
  • Not everyone owns a smartphone. While many of us own and regularly use smartphones, that doesn't account for 100% of the population. 
  • Technological issues. Not all smartphone users are adept at installing and using apps which may reduce usage.
  • Forgetfulness. Some users may simply forget to opt-in or to install the relevant contact tracing app. 
  • You don't have to do anything. Even if you're diagnosed with COVID-19, it's up to you to 'tell' the app that you have it so that others know. 

For cellphone contact tracing to be effective, many studies believe that over half of the population needs to be using it on a regular basis.

What Privacy Concerns Are There With a Contact Tracing App?

No one likes to hand over too much information to a stranger, and understandably, there are privacy concerns tied to contact tracing apps. 

The information is meant to be anonymous so that no one ever knows which person near them may have been infected with COVID-19. However, there are concerns tied to how long anonymous data and information such as where people have traveled will be kept by the relevant agencies. Reassurances vary by country but the general idea is that data will only be held for as long as needed. Google and Apple has already stated they plan to switch off the API involved in making it possible, as soon as it's safe to do so.