The NHS COVID-19 app has been upgraded to include a new version of the Google and Apple API. Among the new improvements are more accurate distance measurements and the removal of confusing exposure notifications.
With the updated API, time data is taken into consideration and signal strength data has been improved. By considering these bits of information as two devices pinging each other, the app will be able to make a better estimate of how close to the other person you are. This update will reduce the chance that you’re told to isolate if you were considered low risk.
Another change is the scrapping of possible exposure and near-miss notifications. These were being sent out by Google and Apple rather than the NHS COVID-19 app and caused a lot of confusion among users who were not sure what to do upon receiving the notification. The app was updated a few weeks ago to send a second notification explaining not to isolate but now they’ve been scrapped altogether and the app will tell users directly if they should isolate.
The app uses a risk scoring algorithm to decide whether people should isolate, by taking into account things like the distance between two devices and how long they have been near each other. With the new update, this has been tweaked according to a new statistical algorithm so that more people will be asked to self-isolate. It said that by lowering the threshold at which people have to isolate, the country has a better chance at reducing the R rate and breaking the chain of transmission.
Millions of people have downloaded the app so far but a few people using iOS devices have complained that they cannot upgrade to the required version of iOS to use the app for some reason or other. If you have an iOS device that should be capable of running the app but need to update iOS first, follow Apple’s helpful guide which explains how to update over-the-air or via a computer.