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CERN introduces proximity detecting device for personnel

New proximity detecting device will help break chains of COVID-19 transmission

CERN's Proximeter
CERN’s contact tracing device, the Proximeter, is being introduced to protect the health of everyone coming on-site. It has been designed to double up as an access card holder. (Image: CERN)

Rapid and comprehensive contact tracing has proven to be an effective way of breaking chains of transmission of COVID-19, and continues to play a central role as the pandemic evolves. At CERN, contact tracing has been in place since the start of the pandemic through a time-consuming interview-based procedure relying on human memory, with all its inherent imperfections, and the delays it entails in identifying possible transmission to close contacts. Furthermore, with the pandemic likely to be with us for some time, the current approach, which places a huge burden on the Medical Service, is not sustainable over the long-term. The new approach is more precise, and delivers more timely information to help CERN break the chains of transmission.

As of next year, CERN’s contact tracing will be improved through the introduction of the Proximeter, a device that everyone with a CERN ID will be required to carry while on-site. Its main purpose is to improve CERN’s response to the challenges of COVID-19, making the Laboratory a safer place for everyone. For the system to work effectively, each and every one of us will need to wear the device while at work. As its name implies, the Proximeter is a proximity sensing device.  It will vibrate to warn its carriers when they move to within two metres of each other for more than 30 seconds, allowing them to move to a safe distance apart. The Proximeter transmits details of the encounter every 15 minutes to a central database in CERN’s main computer centre, protected with state-of-the-art encryption and authentication mechanisms.

The decision to deploy the Proximeter as CERN’s contact tracing device was taken by the Enlarged Directorate (ED) following extensive consultations across the Organization. The ED concluded that the Proximeter enables us to put health first whilst minimizing the intrusion into privacy.

Combating the spread of COVID-19 is the primary objective in rolling out the Proximeter, but privacy has been carefully considered. There is no location tracking – just proximity detection. The Proximeter only knows where it is with respect to other Proximeters. It does, however, know that information to an accuracy far better than that of mobile-phone-based apps, which makes it very good at telling its holders when they are getting too close, while keeping their whereabouts confidential.

When a Proximeter transmits data to the Medical Service’s database, that data is limited to the serial number of the device, and of the devices it has been close to, along with the time and duration of the encounter. Personal data linking the holder to the device number is stored in separate databases, and can only be matched by the Medical Service through a strictly monitored protocol. Data is protected at all times with state-of-the-art encryption and authentication mechanisms, and is held for 14 days before being deleted.

Proximeter data will not be processed automatically: only the data of those who call the Medical Service to declare symptoms, or a positive test, will be looked at. The information on encounters will then be discussed between those concerned and the Medical Service to determine whether or not there is a risk of transmission. Phone-based apps, on the other hand, simply notify the carrier of a close contact with an infected person, requiring self-isolation without a full understanding of the context of the encounter. Deployment of the Proximeter will allow the Medical Service to determine the right course of action following an interview with the persons concerned, which will determine the level of potential contamination, for example by establishing whether masks were being worn.

As of this week, if you are on-site, you may start to see people carrying Proximeters as a pilot run gets underway. Some 950 devices have already been delivered to CERN, and are being deployed among members of key units, such as the CERN Fire and Rescue Service and the Medical Service. Full-scale deployment will begin in January, with details to be communicated when we return to work after the end-of-year break. This will allow us to integrate lessons learned from the pilot period in the general roll-out. The obligation to carry a Proximeter while on-site will begin in March and continue until the pandemic is over. The regulatory framework governing the use of Proximeters will be defined in the CERN COVID-19 health and safety instructions, and published on CERN’s coronavirus information webpages. The FAQ on those pages will also be updated to address any questions you may have about the use of the Proximeter. A training course on the functioning and use of the Proximeter will also be available in January.