At the a blog post published earlier this week, a government official behind the Singapore contact tracking application wrote: “If you ask me if any Bluetooth contact tracking systems deployed or in development, anywhere in the world, are ready to replace manual contact tracking, I will say without qualification that the answer is no & # 39 ;.
Jason Bay, senior director of the Singapore government's digital services agency, added: "You can't & # 39; big data & # 39; get out of a & # 39; no data & period. & # 39; period.
In the publication, entitled “Automated contact tracking is not a coronavirus panacea”, Bay went on to say, “We use TraceTogether to complement contact tracking – not to replace it”.
The Singapore TraceTogether app was released in mid-March. Previously, contact tracking relied on the memory of respondents who tested positive for coronavirus and were asked to recover all recent contacts and movements in detail.
The app works by exchanging short-distance Bluetooth signals between phones to detect other nearby users, recording these encounters over time so that when someone tests positive for the virus, that information can be more easily shared with contact trackers.
However, Bluetooth-based contact tracking solutions do not, by themselves, record location and environment data – this means that it is not possible to know where the contact between cell phones actually occurred, if, for example, it occurred in a park or in adjacent rooms. the same building.
As a result, any automated mechanism will necessarily generate false negatives and false positives.
In addition, the technology does not automatically reveal the user's identity behind a cell phone and number. All of that information still needs to be gathered through a human-led interview process.
A partnership between Google and Apple announced earlier this month, it will assist in mass user adoption – which is a prerequisite for any solution that works effectively – and overcome technical challenges, such as gathering data while an application is in the background and not being actively used.
But the solution still depends on Bluetooth, according to the specifications released by Apple: "The Bluetooth contact tracking specification does not use the location for proximity detection. It strictly uses the Bluetooth flag to detect proximity."
The technology behind the NHSX app should work in a similar way to the Singapore app. Once installed, the application will record the distance between a user's phone and other nearby phones that have also installed it. It uses a form of low-energy Bluetooth to calculate the distance between users, measuring the signal strength of their respective devices. A log of anonymous proximity information is securely stored on the user's phone.
The decision that other users of the app should be notified accurately will be determined by a "contact risk model" within the app – which will be updated continuously to make it as accurate as possible, an NHS source told BuzzFeed News.
The Singapore TraceTogether app about 1 million users – on one sixth of the population – and the island nation has open source and made the underlying protocol available to governments and organizations in other countries.
A white paper that accompanied the launch highlights the need to use an application in conjunction with human-led contact tracking. The paper says: "A human system outside the circuit will certainly produce better results than not having a system, but when there is a competent human system in the sufficient capacity, we warn against over-reliance on technology."
He concludes: “The experience of Singapore contact trackers suggests that contact tracking should remain a human front process. Contact tracking involves an intensive sequence of difficult, anxiety-laden conversations, and it is the role of the contact tracker to explain how a close contact may have been exposed – while respecting the patient's privacy – and to provide assurance and guidance on next steps. "
Asked about the number of people involved in contact tracking, a Singapore government spokesman referred BuzzFeed News to a statement health minister to the country's parliament in March. The minister said that up to 4,000 contacts can be tracked each day and that the contact tracking capacity has grown from 3 to 20 teams and would continue to increase as needed.
By mid-March, Public Health England had screened around 3,500 people in total, including on flights and cruises, with 3% of contacts considered positive during the containment phase of the outbreak and advised to isolate themselves. According a report at Guardian, PHE's contact tracking response team consisted of just under 300 employees at the time.
But contact tracking was reduced in the UK when the number of cases began to grow exponentially and the government's strategy changed from containing the virus to delaying its spread.
A key factor in this decision was the limited testing resources that the United Kingdom had deployed. While Singapore is testing in a rate of about 12,800 per million people, the UK only managed 6,044 tests per million people.
After being the target of widespread criticism, the government promised increase test capacity to 100,000 tests per day by the end of the month, but it’s still very short – on Tuesday, conducted less than 16,000 tests.
When the UK registered its first cases of COVID-19 in late January, PHE said was tracking people who had been in contact with those infected.
After tracking was reduced, a PHE spokesperson said the Guardian that contact tracking was no longer useful because "with this level of sustained community transmission, there is limited value in doing so".
The PHE official blog records this change in strategy.
On February 13, Nick Phin, deputy director of PHE's National Infection Service, I wrote: "At the moment, we do contact tracking to prevent the infection from spreading further. Contact tracking is a key part of outbreak control used by public health professionals worldwide."
The updated coronavirus information page now read: “In the containment phase of the outbreak, we identify all cases, tracking their contacts and monitoring them to determine their level of risk and providing advice and information on what to do if they do not feel well.
“Now, as the virus is more widespread, we won't necessarily be able to determine where someone got it and we will have a more targeted approach to tracking contacts.
“The targeted approach is likely to include tracking close contacts with vulnerable people. For example, those in nursing homes or other institutions. "
A PHE source told BuzzFeed News that contact tracking would play a role in preventing the virus from resurging. Using the experience gained during the containment phase, PHE carefully devised plans to rapidly expand contact tracking, if necessary, they said. PHE was also strengthening surveillance activities to monitor the impact of outbreaks to support local contact tracking.