How it works
What is contact tracing and how does the app work?
Contact tracing identifies people who may be at risk from COVID-19 because they were in close contact with someone who has the virus. By voluntarily choosing to use the Protect Scotland app you will help our NHS by:
- Reducing the time it takes to alert you if you come into close contact with another app user that tests positive
- Alerting other app users that you might have forgotten you were in close contact with
- Allowing us to anonymously alert people who don’t know each other
The app communicates with other app users’ phones using Bluetooth to swap anonymous random IDs when in proximity (2 metres or less) for an extended period of time (15 mins or more). This acts like a virtual handshake between devices, which can then be anonymously recalled if one of the contacts later tests positive for COVID-19. It is important, therefore, that app users keep Bluetooth enabled on their phones as often as possible.
Contact tracing is a vital part of slowing the spread of coronavirus. The more people who download and use the app, the more it will help to stop the transmission of the virus.
What is a contact tracer?
A contact tracer is an individual working for NHS Scotland’s Test and Protect service whose role is to get in touch with individuals who have tested positive for coronavirus or have been identified as a close contact of someone who has tested positive. Contact tracers may get in touch by text, phone or email.
How does the app know who to alert?
Anyone that tests positive for COVID-19 in Scotland will be contacted by a contact tracer, who will ask them about their close contacts and whether they are an app user. If they are an app user, the contact tracer will send them an SMS message with a randomly generated test code to enter into their app.
SMS message with a randomly generated test code to enter into their app.
The app will then seek permission to share the anonymous IDs it has been gathering from close contacts over the past 14 days. These IDs are stored on a secure NHS Scotland server so that other users’ apps can periodically check-in to see if they match up with a positive case.
If there is a match, the app will use a risk calculation to identify which users meet the criteria to trigger a close contact alert:
- Was the contact 2 metres or closer for a period of 15 minutes or more?
- Was the contact during the infectious period of the person that tested positive? (defined as 2 days before the onset of their symptoms; or for those tested positive with no symptoms (asymptomatic), the 2 days before their test date)
This is in-line with the policies currently used by Scotland’s NHS contact tracers.
What are close contact alerts?
If the app finds that you have been in close contact with someone who has tested positive for coronavirus, you will get an alert.
You won’t know who the contact is or where the contact happened. You will just know that you were close enough (within 2 metres) for long enough (at least 15 minutes or more) for there to be a risk.
The app will advise you of what action you need to take, such as isolating at home for several days or booking a test if you experience symptoms.
The app provides links to further information on local/regional lockdowns and support available to help you self-isolate.
What devices can I use the app on?
The app is available for both iOS (Apple) and Android devices.
It uses the most current version of the phone’s operating system to make use of the latest Bluetooth technology. Some users may be asked to upgrade their operating system the first time they use it.
This means iPhones that support iOS 13.5 (or later) such as iPhone 6S and above or Android phones running Android 6.0 and higher.
If you have an older phone and can’t upgrade to the latest operating system, you won’t be able to use the app.
None of the information in this app is ever shared with Apple or Google.
Can I turn off the app?
There are very few circumstances where it is advised to turn the app off. Whilst proximity measurements to identify potential contacts cannot take account of whether the encounter was face to face or whether face coverings/screens were in place etc, they are a good measure of the distance and time spent near a confirmed case and therefore of risk if no other protections were in place.
All app users should therefore keep their phone on and with them whenever possible, with the app active on their phone at all times except in a small number of circumstances:
- If the user is a health or social care worker in a clinical setting, wearing medical grade PPE. This includes ambulance personnel
- If the user is protected by a fixed physical barrier from customers and colleagues such as a Perspex screen for most of the working day. This doesn’t apply for those who constantly move around (e.g. café workers behind tills with a screen who also move around the café)
- If the user keeps their phone in a locker or equivalent facility at work and not on their person
In these circumstances, ideally individuals should turn off their phone as that means the app will automatically continue to work when the phone is turned back on again.
However, it is recognised that that is not always possible so alternatively users can choose to disable Bluetooth. It is also possible for users to turn off the Exposure Notification Setting on their mobile phone. This will turn off the ‘contact tracing’ functionality until the Exposure Notification Setting is switched back on. The user will need to remember to turn their Exposure Notification Settings and/or Bluetooth back on.
If you receive a close contact alert advising you to self-isolate, but believe you meet one of the above scenarios, you can call the National COVID helpline (0800 028 2816) to help you understand the exposure notification and make an informed decision as to whether to self-isolate.
The app should NOT be switched off in the following scenarios:
- Where PPE, including visors and face coverings, is used in non-clinical settings (e.g. building sites, café’s, transport, by fire and police personnel etc.)
- In the home or vehicles (signals from adjoining properties or vehicles are unlikely to result in a contact alert)
Known Differences between Google & Apple?
The Protect Scotland app is built upon Google and Apple Exposure Notification technology and there are some subtle differences between how this works on Apple and Android devices.
The way the Android system handles exposure notifications means that both Bluetooth and location need to be turned on, and the Android system itself notifies you when you turn one or both off, rather than the Protect Scotland app. The onboarding process for Android users includes information about the use of location (it doesn’t use GPS), and the Android version of the app doesn’t have the same ‘tracing inactive’ feature that Apple phones does.
apps users with Apple devices may receive weekly notifications referring to COVID-19 Exposure Logging. These messages are autogenerated by Apple iOS and do not form any part of operation of the Protect Scotland app.
They are not a close contact alert and do not require you to self-isolate.
