How does the app work?
Questions relating to the configuration are best directed to NHSX who are developing the app. It is understood that NHSX are considering some of the following specifications. A person installs the app which starts to record close proximity contacts with other app users. A person develops symptoms and reports these symptoms through self-diagnosis. This person is asked to self-isolate with their household. Their close proximity contacts are anonymously notified, advised to self-isolate, and given further recommendations.
What do the user uptake numbers mean?
Our models suggest we need around 56% of the total population to use the app to completely suppress the epidemic, if combined with ‘shielding’ of over 70s (see below). Usage requirement may be lower if the app is used in conjunction with further social distancing interventions. Lower usage has the effect of slowing resurgence and potentially delaying the start of a second lock down.
How does testing relate to the app?
Using self-diagnosis, based on a series of questions, will rapidly trigger notifications encouraging other people to isolate before they become infectious. Testing app users after they self-report could ensure the quick release of contacts if the test is negative. Starting contact tracing only after a positive test is less effective at suppressing the epidemic, as crucial time is lost during which contacts are already infectious. If testing can be scaled up and sped up, it could be a valuable addition to the digital contact tracing process.
How are the elderly accounted for with smartphone usage?
Using the latest data on smartphone usage by age, sourced from the UK’s communications regulator OFCOM, the model does not include over 70s in the contact tracing process due to low smartphone usage on average. This vulnerable group will still benefit from protection if they are quarantined, in accordance with UK policy on ‘shielding’. Even people not using the app will receive some protection from its effect, through decreased transmission in the community.
What if not many people use the app?
Our simulations suggest a reduction in the number of coronavirus cases and deaths even with low numbers. We estimate that we prevent approximately one infection for every one or two users of the app. Moderate uptake will also still result in delaying the need for a second lockdown. The app is a tool for anonymously and instantaneously communicating information from infected persons to recent close proximity contacts. The effectiveness of the policy in controlling the epidemic is dependent on users responding to the guidance; the app requires a public health campaign that encourages appropriate use and response, and will need to build trust from users in the effectiveness of the system.
What are some of the scenarios for configuring the app?
See Figure 1. Enlarge image to view full details. Dr. Rob Hinch, senior researcher at Oxford University’s Nuffield Department of Medicine, “Our simulation results present five key scenarios with various amounts of contact tracing and strategies for releasing people from quarantine, which we compare to a simulation of the epidemic with no contact tracing at all. Our mathematical model allows governments and app developers to compare different app configurations, exploring how each impacts differently on the epidemic.”
Figure 1. Enlarge image to view full details. Credit: Fraser Group, Oxford University’s Big Data Institute, Nuffield Department of Medicine. The icons used are taken from Font Awesome and licensed under the Creative Commons Attribution 4.0 International license.
Comments