Contact-tracing apps 'will only work if universal'

British study shows three-quarters of the population would need to sign up

With novel coronavirus cases once again surging in many European nations, researchers from University College London have warned that the vast majority of people in the United Kingdom will need to use contact-tracing apps if they are to be successful in stopping the spread of the virus that causes the COVID-19 disease.

They also said the government will need to invest heavily in its manual track-and-trace programs for them to work properly.

The study, which was led by Isobel Braithwaite of UCL's Institute of Health Informatics, analyzed more than 4,000 research papers that have been published during the past 20 years in order to better understand how and when such apps work best.

They found the R rate — the average number of people being infected by a person with the virus — can only be driven down below 1 if track-and-trace apps are used by at least three-quarters of the population. And they said the apps must run alongside ambitiously large manual contact-tracing systems.

"We can't see it as a silver bullet," the Financial Times quoted Braithwaite as saying.

The UK government said last week it is now ready to start testing a new version of a contact-tracing app that it abandoned in June.

Braithwaite told the Financial Times that such apps are unlikely to work to the extent that they will allow life to return to normal.

"Certainly, it was my perception during that April lockdown period that governments wanted to suggest that this would be the panacea that would enable us to get back to normal and forget about COVID; and if we could get this right, it would solve all of our problems," she told the paper.

The sobering assessment came as many European nations have reported surging novel coronavirus cases, and as Johns Hopkins University researchers updated the worldwide COVID-19 death toll to at least 787,000 people.

Spain reported 3,715 new novel coronavirus infections on Wednesday, the largest number since the nation emerged from a strict lockdown at the end of June. Italy reported 642 new virus cases on Wednesday, its largest daily total since late May. And Germany said on Thursday its 1,707 new cases were the most it has had since April.

Experts believe the spikes are partly down to people visiting other nations for holidays.

The risk posed by returning vacationers has prompted most nations to introduce travel restrictions, with the latest country to be blocked by its neighbors being Croatia, which has emerged as a virus hot spot. It reported 219 new COVID-19 cases on Wednesday, including one involving a top-flight soccer player.

The UK wants to get a clearer picture of the virus situation within its borders and said on Thursday it will begin testing 150,000 people every two weeks, instead of the current 28,000 who are taking part in an Office for National Statistics survey. The group will be a representative sample of the nation's population and the project will differ from other testing programs because they largely target people who have symptoms, or who think they may have contracted the virus.

The BBC said the government hopes the greatly enlarged survey will help identify how many people have the virus but no symptoms.

Health Secretary Matt Hancock has also said he would like to see faster results for members of the public who suspect they may have the virus. He said on the BBC show Breakfast that the government is assessing the effectiveness of new types of spot-testing because it sees the task of identifying asymptomatic carriers as its "biggest challenge".

The latest official estimate said 28,300 people in England were carrying the novel coronavirus last week, which equates to one person in every 1,900.

Meanwhile, the extent of the mental strain caused by the pandemic became clearer on Thursday with the release of new data from the ONS that shows twice as many UK adults now have symptoms of depression than did last year.

The ONS surveyed more than 3,500 adults during a 12-month period and found one person in every five now has depression symptoms, which include changes in sleep patterns, loss of appetite, lack of motivation, and difficulty in concentrating.

Those most affected included people under the age of 40, women, people with a disability, and the poor.

Stephen Buckley, head of information at the charity Mind, told the BBC: "It's important to bear in mind that most of us will have found the last five or six months more difficult than usual, and there's no 'normal' way to respond to a pandemic."