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A team of medical researchers and bioethicists at Oxford University has outlined the feasibility of using digital contact tracing via mobile phone apps as a way of quickly alerting people who have been in contact with newly diagnosed coronavirus patients to self isolate. The researchers say that if widely used, such apps could help to significantly slow the rate of coronavirus spread, and reduce transmission when lockdowns are lifted and restrictions are gradually eased. Their results are being used by NHSX, a joint unit comprising teams from NHS England and the U.K.’s Department of Health & Social Care, and the Norwegian Institute of Public Health (FHI), to assess the potential to develop mobile apps as a strategy for instant contact tracing. Apps with similar aims have already been deployed in China, the Oxford team noted, where they weren’t compulsory, but were required for people who needed to move around in public places.

“The mobile app concept we’ve mathematically modeled is simple and doesn’t need to track your location,” explained David Bonsall, PhD, senior researcher at Oxford University’s Nuffield Department of Medicine and clinician at Oxford’s John Radcliffe Hospital, who co-led the report, which is published in Science. “It uses a low-energy version of Bluetooth to log a memory of all the app users with whom you have come into close proximity over the last few days. If you then become infected, these people are alerted instantly and anonymously, and advised to go home and self isolate. If app users decide to share additional data, they could support health services to identify trends and target interventions to reach those most in need.”

The researchers’ findings are detailed in a paper titled, “Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing.”

With no treatments for COVID-19 infections currently available for the general population, and the prospect of a vaccine yet months away, “The only approaches that we currently have available to stop the epidemic are those of classic epidemic control, such as case isolation, contact tracing and quarantine, physical distancing, and hygienic measures,” the authors reported. They carried out an analysis of key parameters of epidemic spread, to estimate the relative contribution of different transmission routes, and work out the requirements for case isolation and contact tracing that would be needed to stop the epidemic. They concluded that the virus spreads far too quickly to be contained by manual contact tracing, but could feasibly be controlled—and the need for lockdowns potentially prevented—if this tracing process was faster, more efficient, and happened at scale. “A contact tracing app that builds a memory of proximity contacts of positive cases can achieve epidemic control if used by enough people,” they wrote.

People who develop coronavirus symptoms could request a diagnostic test through the app, if diagnosed positive, the app would then immediately alert their recent close contacts an prompt them to self-isolate. “The core functionality is to replace a week’s worth of manual contact tracing with instantaneous signals transmitted to and from a central server,” the investigators noted. “Coronavirus diagnoses are sent to the server, enabling recommendation of risk-stratified quarantine and physical distancing measures in those now known to be possible contacts, while preserving the anonymity of the infected individual.”

The authors suggested that by targeting recommendations to only those at risk, the app could potentially contain epidemics “without the need for mass quarantines (‘lock-downs’) that are harmful to society.” They noted that a mobile app could reduce transmission at any stage of the epidemic, in countries or regions where the epidemic is just emerging, at the peak of the epidemic, or to support safe transition out of restricted movement or lockdown. An app strategy could also be adopted by low- and middle-income countries, earlier in the epidemic, to help control transmission and get ahead of the epidemic.

It could also help to reduce the social, psychological, and economic impacts caused by widespread lockdowns. Co-lead author Christophe Fraser, PhD, from Oxford University’s Big Data Institute, Nuffield Department of Medicine, further commented, “A contact tracing app can foster good citizenship by alerting people at risk, it can also help ease us out of confinement. If we know we’ve not been in contact with anyone infected we can leave home safely, whilst still protecting our loved ones and avoiding a broader resurgence of coronavirus in our community.”

The widespread use of such a mobile app would massively reduce transmission and potentially reduce the chance of resurgence in the number of cases across Europe, providing an opportunity for all citizens using mobile contact tracing apps to contribute towards ending the epidemic. “We need a mobile contact tracing app to urgently support health services to control coronavirus transmission, target interventions, and keep people safe,” stated Fraser. “Our analysis suggests that about half of transmissions occur in the early phase of the infection, before you show any symptoms of infection. Our mathematical models also highlight that traditional public health contact tracing approaches provide incomplete data and cannot keep up with the pace of this pandemic.”

The Oxford team highlighted that the mobile contact tracing app approach should still be combined with case isolation, tracing, and quarantine of contacts, physical distancing, increased diagnostic testing, decontamination, and hygiene measures.

“It is noteworthy that the algorithmic approach we propose avoids the need for coercive surveillance, since the system can have very large impacts and achieve sustained epidemic suppression, even with partial uptake,” the authors concluded. “People should be democratically entitled to decide whether to adopt this platform. The intention is not to impose the technology as a permanent change to society, but we believe it is under these pandemic circumstances it is necessary and justified to protect public health.” The app could feasibly act as a central hub for people to access to COVID-19-related health services and information, and potentially, the team projects, for people to request food and drug deliveries during isolation

Bonsall further commented, “If the mobile app is widely adopted in any country, and combined with other critical interventions such as physical distancing and widespread testing, our models suggest the epidemic could be brought under control. This app is a tool for each and every person affected to contribute towards protecting their health services, supporting vulnerable people and simultaneously gradually releasing communities out of extended quarantine.”

The team’s study in Science highlights the importance of rigorous ethical standards underpinning the successful and appropriate use of mobile phone technology in addressing the coronavirus pandemic; including a number of ethical requirements needed to foster well-founded public trust and confidence. Co-author Michael Parker, PhD, director of the Wellcome Centre for Ethics & Humanities, commented, “With transparent and inclusive ethical oversight to ensure genuine public trust, it is possible to both save lives and protect civil liberties. The app should be opt-in, provide secure data storage and privacy protection, and be informed by public and user engagement at every stage of implementation. With these guarantees and, if widely installed by users across a country or regional bloc, a mobile app could even help to end the epidemic.”

As mobile apps launch over the coming weeks and months, the Oxford research team urges people to support technologies developed by trusted institutions, and their partners, such as the mobile contact tracing apps under advanced assessment in several European countries. Fraser concluded, “Our hope is to support communities with life-saving information as the pandemic worsens, and help to release countries from large-scale isolation. The math is clear: the more people that use a contract tracing app the better chance we have of getting ahead of this epidemic and eventually stopping it in its tracks. If a country reduces the epidemic growth rate to below zero, the epidemic will rapidly decline and eventually stop. Together we can make this possible.”


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