Health ministry officials said the system is still in its infancy and should not be used frequently.
But with massive pub and bar closures expected in parts of the country, the lack of targeted alerts at the scene has raised questions about the government’s strategy.
Shadow Minister of Digital Chi Onwurah said: “On the one hand, during a government briefing on local data, I was told that pubs are the main location COVID Exposure, on the other hand, the contact tracing app sent only one alert about an outbreak in a location.
“There is a glaring contradiction here and the ministers must pull themselves together. ”
The app has now been downloaded 16 million times, in part thanks to its QR code scanner, a feature built into the app in addition to the contact tracing system, which tells users whether or not they have been to proximity to a person who tested positive. for coronavirus.
The QR code scanner allows people to check in at places such as pubs and restaurants. If there is an outbreak in a location then NHS Test and Trace can send an alert to anyone who has visited.
Ministers hailed the system as a crucial step and passed a new law banning bars, restaurants and pubs from displaying an official NHS QR code.
Three days after the app launched on Thursday, September 24, the Department of Health and Social Affairs boasted that more than 480,000 businesses had downloaded posters of QR codes.
That Saturday, Test and Trace recorded over 1.5 million check-ins in a single day.
But a data file in the app’s code, uncovered by Sky News, shows only four alerts were sent of outbreaks at the locations, three of which expired before the app launched nationwide.
The app code also revealed the text of the alert that will be sent in the event of an outbreak at a location, exposing the challenges of using a system designed to protect the privacy of public health communications.
Data on the records is stored locally on the phones, so when the app sends an alert about an outbreak, it cannot name the location where the outbreak took place. Instead, he says, “We are letting you know that you may have been exposed to the coronavirus while you were away. ”
Paul Hunter, professor of health protection at the University of East Anglia, said this lack of detail meant that site alerts “almost certainly cannot be seen as an important and effective means of controlling the epidemic ”.
The app’s privacy-friendly design also means that unlike other manual or QR-based registration systems, public health officials cannot look at the data to see who has registered on a site using the app, a fact Professor Hunter said he asked him if the app was a barrier to effective virus control.
“If everything is done through the app and Public Health England and local public health teams don’t know, is that making the outbreak worse? ” he said. “He could act to hide clusters and epidemics from local public health teams.
“If that happens, then it’s a really serious problem and it will undoubtedly be more difficult to control the epidemic. ”
Senior officials at Test and Trace have championed the system, saying it makes registration easier and more accurate, while encouraging wider adoption of the app. They pointed out a similar recording application in New Zealand which they said had been very successful.
Yet although the registration system works in both England and Wales, the Welsh government has not required businesses to display NHS QR code posters and has continued to ask pubs and restaurants to ‘record details manually or through their own QR record. systems, which do not have the same privacy constraints on data collection.
A Welsh government official said he wanted to avoid disrupting existing contact tracing efforts in the country.
A spokesperson told Sky News: “Our contact tracing system, which is a public service and provided locally, is working very well, with a very high contact and follow-up rate. ”
Asked about the difference between the Welsh and English systems, a senior Test and Trace official said it was up to each country to decide, noting that manual recording logs tend to be filled with Mickey Mouses and Donald Ducks.
In order to send an alert, public health officials add the code for that location to a data file, which is automatically sent to every contact tracing application several times a day. The app then checks to see if the codes in the file match any of the places the user has checked in.
Rather than giving specific advice, the alert asks people to watch out for symptoms, a strategy described by DHSC officials as “warn and inform.”
After saying, “We are letting you know that you may have been exposed to the coronavirus”, the alert continues: “Although there is only a small risk that you were infected during your visit , please continue to follow the latest advice on social distancing. He then asks users to “use the symptom checker on the app and book a free test if advised to do so.”
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Health officials described the QR registration system as an additional feature of the app that would only be used if a location was linked to an outbreak, which they didn’t expect to happen. frequently.
Asked about the lack of alerts on the scene in the fortnight following the launch of the app, a spokesperson for the Department of Health and Social Affairs said: “The NHS Covid app is a public health tool important, downloaded over 16 million times, which helps stop the spread of this virus.
“Along with the app’s contact tracing features, the QR code recording system performs a number of important functions, including providing a digital diary for users to ask them who they have been with if they test positive. .
“If health protection teams believe a site is linked to an outbreak, they can send a warning message and notify app users who visited the site at a similar time in depending on their registration.