Contact tracing app useless until test and trace working

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Since the Covid-19 app was finally launched three weeks ago it has been beset by glitches, inaccuracies and low download rates.

Not only has the app come out months after similar mobile phone apps in other countries, but is believed to have costed over £35 million to get this far. This is in contrast to apps in countries such as Ireland, which have come in under £1 million.  

With infection rates soaring across the UK and track and trace systems failing to fulfil demand in order to be effective, the failure to have an appropriate app is starting to exacerbate a worsening problem.  

The phone app for contact tracing in perspective

Mobile phone apps are among the modern epidemiologist’s tools for the fight against infectious disease. South Korea has had one of the lowest case mortality rates in the world and together with widespread testing also employed mobile phone technology to track peoples movements. App based tracing has attractions when the majority of the population own a smart phone that can be set up to communicate with other devices and keep a record of when two phones come into proximity. If someone reports through the app that they have symptoms, the app gives information about how to get tested. Should the user later notify the app that they have tested positive, an alert can automatically be sent to other phones that were nearby in recent days. This fills in some of the work previously done by contact tracers who have to ask people who have tested positive for the virus to tell them who they might have been in contact with and then follow up those people by telephone. Manual tracing, while slower, has the advantage of someone to talk to when news of a positive result is broken and also reaches people that are unable or unwilling to use a smart phone. A manual and app-based tracing system could be used in conjunction with each other to reach a wider section of society, which is crucial when dealing with infectious disease.

How many app users are needed?

One study using mathematical modelling suggested an app-based strategy achieved only a 44% reduction in transmission, whereas manual tracing reduced transmission by 61%. This assessment was based on the assumption that 53% of the population would download and use the contact tracing app. When the case for a contact tracing app was originally made, the number of smart phone users needed to run and adhere to the app in order to effectively suppress transmission was estimated to be 60% - or 80% of owners. Importantly, only around 79% of the UK population own a smartphone, and it is estimated that 13% lack the skills to open an app. These figures raise questions about whether the benefits of the app will go to those who need them most. False alerts will also be generated and these may have unintended consequences. Some groups could be hit by repeated instructions to self-isolate, with a greater impact on their ability to work. Will this disproportionately affect people more likely to already find themselves in difficult financial situations?

Demotion from game changer to cherry

Early on in lockdown, Health Secretary Matt Hancock was hugely enthusiastic about a UK home grown mobile phone app, describing it as central to getting “our liberty back” and even suggesting the public had a “duty” to download and use. However, the security of the app was challenged, and journalists reported its development was being dogged by problems including a data-hungry approach, an attempt to defy Apple and Google, intra-agency bickering and a problematic test run on the Isle of Wight. The app used a centralised model, meaning that the data was not just kept on an individual’s phone, but collected centrally by government, unlike most other European countries where a more privacy-protecting decentralised model was chosen. The UK approach was heavily criticised by Amnesty International among other organisations, and lack of trust seemed guaranteed to reduce its appeal among the public.  In the event, the deadline for being rolled out in mid-May passed quietly, and in June, the app was downgraded to only ‘the cherry on the cake’ - no longer a key part of the contact tracing strategy. On 18th June, after £12 million spent on technology that experts had repeatedly warned would not work, it was made clear that the project had finally been abandoned.

New app – new problems

Despite data on the Isle of Wight trials never being made public, a new app for smart phones was launched on the 24th September. The app uses Bluetooth technology to log the amount of time a person spends near other app users, records the distance between them, and alerts users when they have been close to people who later test positive. Privacy is protected by generating a random ID for an individual’s device and not holding personal information such as name, address, or date of birth.  Users are also told the level of coronavirus risk in their district; they can scan into venues to see if they could have been exposed to infection; check symptoms; book a test and get results; and count down time to end of self isolation.

Immediately following its launch, thousands of people who had tests for COVID-19 in NHS hospitals and Public Health England laboratories were unable to share their results with the app. The Department of Health and Social Care subsequently said that it had fixed the glitch, but the problem meant that more than 60, 000 tests could not be linked to the app. More recently, users of the app have reported receiving updates incorrectly telling them the risk level in their area had changed, after a mistake by the app's developers.

A question of trust

Since the public are being asked to trust their safety to an app it seems reasonable for the public to have access to information about how well the app is working; whether this will happen remains to be seen. After the examination results debacle, the app also prompts concern as to whether it is reasonable to expect people to self-isolate based on the results of an algorithm. There is no doubt that if the app is to be widely used a high level of trust in government will be needed, something now in short supply and greatly eroded by the Dominic Cummings affair. Fines for not self isolating may mean some choose not to use the app in case it brings unwanted direction to do this. In addition, the fact that contact details of those who have been told to self-isolate by NHS Test and Trace are to be passed to the police on request may further undermine public trust in the system.

No magic bullet

Hancock was correct to revise his opinion on the importance of the app. Even if it does in fact have the potential to be more than just a cherry on the cake, it is still only one plank of a raft of measures needed to keep transmission of virus under control, including hygiene and social distancing. For people to comply, we need not only trust that we really are all in it together, but also support, including financial support, to make self isolation a feasible option for many. The app complements manual contact tracing but most importantly is contingent on an effective testing system. Official data shows that in the week up to 16 September, the results of just 28% of swab tests were received within 24 hours, down from a third the week before. Only 77.7% of the close contacts of people transferred to NHS Track and Trace were reached (83.8% the previous week). As one expert observed: “The usefulness of the app is completely tied to getting testing and return on tests fixed. Unless you can get testing and return on testing down to about three days, then the app isn’t going to do anything useful. It’s not a magic bullet”. This emphasises the need for testing and tracing to be brought back into local authority and NHS structures and the secretive contracts with private companies such as Serco (now boasting huge profits) terminated.

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