Early within the pandemic, the COVIDSafe app was designed as a instrument to enhance contact tracing. And a multimedia marketing campaign promoted it as serving to to seek out extra COVID contacts quicker.
Now, nearly two years after its launch in April 2020, we publish in The Lancet Public Well being our analysis of the app’s effectiveness and usefulness in New South Wales.
We analysed knowledge from all 619 COVID instances recorded in NSW above the age of 12 and their contacts between Might and November 2020. We additionally interviewed contact tracers about whether or not they thought-about the app helpful.
Our evaluation confirmed the app didn’t add a lot worth to the prevailing, typical contact tracing system.
A complete of twenty-two% of instances had been utilizing the app. Most (61%) contacts the app registered as “shut contacts” turned out to not be epidemiologically linked to a case. The app detected solely 15% of true shut contacts recognized by typical contact tracing.
In whole, COVIDSafe detected solely 17 further true shut contacts in NSW through the six-month analysis interval.
It precipitated substantial further work for contact tracers and general, didn’t make a significant contribution to the COVID response in NSW.
Tracing takes time
Interviewing new instances to determine, hint and isolate their shut contacts is an important public well being exercise. However that is time-consuming and get in touch with tracers can grow to be quickly overwhelmed when case numbers rise.
Digital contact tracing apps had been enthusiastically embraced early within the COVID pandemic in many international locations, together with Australia.
Like many different tracing apps, COVIDSafe makes use of smartphones’ built-in Bluetooth operate to change alerts between telephones.
The length, frequency and transmission power of those “digital handshakes” are used to find out whether or not two smartphone customers have come into “shut contact” with one another.
Low potential to detect and determine shut contacts accurately
Throughout our examine interval, lower than 1 / 4 of all instances had been utilizing the app. That is half the proportion of the Australian common public who did so.
Of these instances who used the app, many had not a single contact registered by the app. For others, contact tracers couldn’t entry the app knowledge.
Contact tracers may use app knowledge for 32 (5%) of the 619 instances over our examine interval. Of these instances, solely 79 (39%) of the 205 contacts the app registered as “shut contacts” may very well be verified as true shut contacts. This means poor optimistic predictive worth of the app.
Examples of false shut contacts the app registered had been:
- neighbours in numerous flats in residence buildings
- workplace staff in adjoining rooms
- prospects in neighbouring eating places
- folks ready in separate vehicles at COVID drive-through testing clinics.
The overwhelming majority (85%) of shut contacts recognized by typical contact tracing weren’t detected by the app, indicating low sensitivity.
A couple of further contacts detected
Throughout the six months of our examine, there have been solely 17 true shut contacts recognized by COVIDSafe who would have in any other case been missed – a tiny fraction of the greater than 25,300 shut contacts detected and adopted up via typical contact tracing in NSW throughout the identical interval.
None of those 17 contacts grew to become optimistic. So COVIDSafe didn’t contribute to stopping any new exposures in NSW throughout our analysis interval.
Contact tracers didn’t discover the app simple to make use of. Some stated the app didn’t appear to work as reliably on all sorts of telephones. The variety of contacts on iPhones had been considerably underestimated, whereas these from Android telephones had been overestimated.
Contact tracers additionally famous the app’s obvious incapacity to correctly register contacts except it was open. This may clarify the big variety of instances with none registered contacts in our examine.
The method of cross-matching shut contacts recognized by the app with these recognized via case interviews was seen as time-consuming, notably as most contacts picked up by the app had been probably not shut contacts.
Interviewed workers stated this might simply overwhelm the contact tracing system had case numbers been greater, paradoxically resulting in a discount in usefulness of the app when it will be most wanted.
Total, contact tracers’ perceptions of the app ranged from “not impacting a lot” to being an extra step that elevated workload with out including a lot worth.
Little added worth at excessive prices
In our examine, COVIDSafe didn’t make a significant contribution to the COVID response in NSW throughout 2020. As an alternative, the app created a excessive workload for no clear profit.
This stands towards the A$7.7 million it has price to develop and run COVIDSafe till the top of April 2021, with an estimated $60,000-$75,000 per thirty days in upkeep since.
The arrival of the extremely transmissible Omicron variant in late 2021 in Australia, coinciding with the lifting of most public well being restrictions, led to huge enlargement in case numbers, forcing a sequence of main changes to contact tracing.
In most elements of Australia, contact tracing now has a really restricted position in COVID management. Nonetheless, it’s prone to stay a key public well being intervention for infectious illnesses sooner or later.
For digital contact tracing apps to be efficient and helpful, it will likely be essential to contain contact tracers when designing the system, to street take a look at the underlying expertise in real-life settings, and to judge the app usually after roll-out.
Dr Anthea Katelaris, a public well being doctor who labored on the Western Sydney Native Well being District public well being unit on the time of the examine, co-authored the analysis talked about on this article.
- Florian Vogt, Senior Analysis Fellow, The Kirby Institute, UNSW; Bridget Haire, Senior Analysis Fellow, Kirby Institute, UNSW; John Kaldor, Professor of Epidemiology, UNSW, and Linda Selvey, Affiliate Professor, College of Public Well being, The College of Queensland