Is the UK’s pingdemic good or bad? Yes.

Oscar Maung-Haley, 24, was working a part-time job in a bar in Manchester, England, when his phone pinged. It was the UK's NHS Test and Trace app letting him know he'd potentially been exposed to covid-19 and needed to self-isolate. The news immediately caused problems. It was a mad dash around the venue to show my manager and say I had to go," he says.

The alert he got was one of hundreds of thousands being sent out every week as the UK battles its latest wave of covid, which means more and more people face the same logistical, emotional, and financial challenges. An estimated one in five have resorted to deleting the app altogether-after all, you can't get a notification if you don't have it on your phone. The phenomenon is being dubbed a pingdemic" on social media, blamed for everything from gas shortages to bare store shelves.

The ping deluge reflects the collision of several developments. The delta variant, which appears much easier to spread than others, has swept across the UK. At the same time, record numbers of Britons have downloaded the NHS app. Meanwhile, the UK has dropped many of its lockdown restrictions, so more people are coming into more frequent contact than before. More infections, more users, more contact: more pings.

But that's exactly how it's supposed to work, says Imogen Parker, policy director for the Ada Lovelace Institute, which studies AI and data policies. In fact, even with so many notifications being sent, there are still many infections that the system is not catching.

More than 600,000 people have been told to isolate by the NHS covid-19 app across the week of July 8 in England and Wales," she says, but that's only a little more than double the number of new positive cases in the same period. While we had concerns about the justification for the contact tracing app, criticizing it for the pingdemic' is misplaced: the app is essentially working as it always has been."

Christophe Fraser, an epidemiologist at the University of Oxford's Big Data Institute who has done the most prominent studies on the effectiveness of the app, says that while it is functioning as designed, there's another problem: a significant breakdown in the social contract. People can see, on TV, there are raves and nightclubs going on. Why am I being told to stay home? Which is a fair point, to be honest," he says.

It's this lack of clear, fair rules, he says, that is leading to widespread frustration as people are told to self-isolate. As we've seen throughout the pandemic, public health technology is deeply intertwined with everything around it-the way it's marketed, the way it's talked about in the media, the way it's discussed by your physician, the way it's supported (or not) by lawmakers.

People do want to do the right thing," Fraser says. They need to be met halfway."

How we got here

Exposure notification apps are a digital public health tactic pioneered during the pandemic-and they've already weathered a lot of criticism from those who say that they didn't get enough use. Dozens of countries built apps to alert users to covid exposure, sharing code and using a framework developed jointly by Google and Apple. But amid criticism over privacy worries and tech glitches, detractors charged that the apps had launched too late in the pandemic-at a time when case numbers were too high for tech to turn back the tide.

So shouldn't this moment in the UK-when technical glitches have been ironed out, when adoption is high, and with a new wave spiking-be the right time for its app to make a real difference?

The science is not as much of a challenge ... the challenge comes around the behavior. The hardest parts of the system are the parts where you need to convince people to do something."

Jenny Wanger, Linux Foundation Public Health

Not if people don't voluntarily follow the instructions to isolate, says Jenny Wanger, who leads covid-related tech initiatives for Linux Foundation Public Health.

Eighteen months into the pandemic, the tech is not usually a challenge," she says. The science is not as much of a challenge ... we know, at this point, how covid transmission works. The challenge comes around the behavior. The hardest parts of the system are the parts where you need to convince people to do something-of course, based on best practices."

Oxford's Fraser says that he thinks about it in terms of incentives. For the average person, he says, the incentives for adhering to the rules of contact tracing-digital or otherwise-don't always add up.

If the result of using the app is that you end up being quarantined but your neighbor who hasn't installed the app doesn't get quarantined," he says, that doesn't necessarily feel fair, right?"

To make matters even more complicated, the UK has announced that it's about to change its rules. In mid-August, people who have received two doses of a vaccine will no longer need to self-isolate because of covid exposure; they'll only need to do so if they test positive. About half of the country's adult population is fully vaccinated.

That could be a moment to bring incentives more in line with what people would be willing to do, he says. Maybe people should be offered tests so that they can keep going to work and get on with life, rather than be isolated for a number of days."

In the meantime, though, a handful of corporate leaders-the head of a budget airline, for example-have encouraged employees to delete the app to avoid the pings. Even the two most powerful politicians in the country, Prime Minister Boris Johnson and Chancellor Rishi Sunak, tried to skirt the requirement to isolate after being pinged (saying they were taking part in a trial of alternative measures) before public outcry forced them into quarantine.

When protection creates confusion

The mixed messages are compounded by the app's privacy-protecting functions. Users aren't told who among their contacts may have infected them-and they're not told where any interactions happened. But that isn't an accident: the apps were designed that way to safeguard people's information.

In epidemiology, surveillance is a noble thing," says Fraser. In digital tech, it's a darker thing. I think the privacy-preserving protocol got the balance right. It's incumbent on science and epidemiology to get information to people while preserving that privacy."

Be that as it may, those privacy protections are now creating even more confusion.

Alistair Scott, 38, lives with his fiancee in North London. The couple did everything together during lockdown-yet Scott recently got a notification telling him he needed to isolate, while his partner did not. It immediately became this game of Why did I get pinged and you didn't?'" he says.

What's next

Experts say that there are a few ways forward. One could be to tweak the algorithm: the app could incorporate new science about the length of covid exposure that might merit a ping even if you're vaccinated.

Emerging evidence looks like full vaccination should decrease the risk that someone transmits the virus by around half," says Parker of the Ada Lovelace Institute. That could have a sizeable impact on alerts if it was built into the model."

That means alerts could become less frequent for vaccinated people.

On the other hand, Wanger says that NHS leaders could adjust settings to be more sensitive, to reflect the increased transmission risk of variants like delta. There's no indication that such changes have been made yet.

Either way, she says, what's important is that the app keep doing its job.

As a public health authority, when you're looking at cases rising dramatically within your country, and you're trying to pursue economic goals by lifting lockdown restrictions-it's a really hard position to be in," Wanger says. You want to nudge people to do behavior changes, but you've got this whole psychology aspect to it. If people get notification fatigue, they are not going to change their behavior."

Meanwhile, people are still being pinged, still feeling confused-and still hearing mixed messages.

Charlotte Wilson, 39, and her husband both downloaded the app onto their phones almost as soon as it was available. But there's been a split in the household, especially since lawmakers were seen apparently trying to avoid the rules. Faced with the prospect of being told to self-isolate, Wilson said she would follow the advice, while her partner felt differently and deleted the app completely.

My husband thought [over the weekend], You know what? This is ridiculous,'" she says. The impending change in self-isolation protocol made it seem especially fruitless.

Still, she understands his view, even if she's personally keeping the app on her phone.

I don't really know what the answer is as far as society's concerned," she says. We're just riddled with covid."

This story is part of the Pandemic Technology Project, supported by The Rockefeller Foundation.