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How Apple and Google are addressing one of the most difficult parts of tracking COVID-19 exposures


Around here we say that The Interface runs Monday through Thursday, and Fridays are particularly newsworthy. Well, today was a particularly new Friday. Here’s your emergency bulletin …

On Thursday night I wrote about some of the limitations on using the Bluetooth chip in your smartphone to track the spread of COVID-19. Naturally, on Friday morning, Apple and Google announced what could be the most significant collaboration in the history of the two companies – a joint effort to use the Bluetooth chip in their smartphone to track the spread of COVID-19.

Russell Brandom and Adi Robertson had the details in The Verge:

The new system, which is featured in a series of documents and white papers, would use short-range Bluetooth communications to establish a voluntary contact tracking network, keeping extensive data on phones that have been close to each other. The official applications of public health authorities will have access to this data, and users who download it can report whether they have been diagnosed with COVID-19. The system will also alert people downloading them if they were in close contact with an infected person.

Apple and Google will introduce a pair of iOS and Android APIs in mid-May and will make sure that the apps from these health authorities can implement them. During this phase, users will still have to download an app to participate in contact tracking, which could limit adoption. But in the months after the API ends, companies will work on creating tracking functionality in the underlying operating system, as an option immediately available to everyone with an iOS or Android phone.

If you’re new to the idea of ​​how contact tracing helps stop the spread of disease, start with this explainer from my colleague Nicole Wetsman. Public health agencies have sent workers, both on foot and by phone, to contact people who may have been exposed to someone with an infectious disease. In light of the COVID-19 pandemic, countries around the world have been experimenting with applications that attempt to use the widespread adoption of smartphones and the signals they receive to identify potential new cases. And as I exposed yesterday, public health officials with whom I have spoken have expressed skepticism about the effectiveness of such efforts.

Let me first say that I am pleased to see that large corporations work hard on the COVID-19 response and work together. Fast, bold action can save lives, and it’s okay that not everything you try works perfectly, or at all. It’s also true that, given the number of questions remaining around the Apple/Google collaboration, it’s impossible to say at this point how effective it could be. I hope it is very effective!

That said, Bluetooth-based approaches to contact tracking have at least three big problems, experts have told me. (Privacy, surprisingly, isn’t one of them, at least not to me; the Apple/Google system privacy design is pretty smart. Moxie Marlinspike has some objections, though.) Biggest problems are: it’s hard to get people to download a new app, Bluetooth signals can be unreliable, and focusing on technology solutions could reduce pressure on public health agencies to hire people to track of contacts, even though there is much more evidence of the effectiveness of these workers than there is for smartphone applications

So, let’s see how the Apple/Google collaboration seeks to address some of these points.

The most important part of the problem that the API project tries to handle is adoption, particularly in the second phase of the project. Apple explained it to me this way: Once you update your phone to the latest version of the operating system and subscribe to the Contact Tracking API, your phone will start sending Bluetooth signals to nearby phones and recording signals that others send you. The best part of this system is that it works retroactively: once you download a public health app linked to this system, you will share your “proximity events” for the past 14 days. Adi Robertson details the process here.

By creating a core API across our two major smartphone operating systems, Apple and Google are providing a valuable tool for public health agencies working on contact tracking applications that will work in jurisdictions around the world, even when people begin to resume your travels. It’s hard to imagine doing something like this in any way other than at the operating system level; only these two companies could make something like this possible.

An open-ended question is whether you will be bothered by exposure if you updated your phone’s operating system but did not download a public health application. It seems that the answer is yes, based on what we have seen, which would go further to address the issue of adoption than any other proposal I have seen. If the answer is that you still have to download an app to receive the notification, the basic problem is not gone.

We’ll see.

So what about the reliability of Bluetooth signals? A strong signal has a range of approximately 30 feet, well beyond the 6-foot distance that authorities have asked the public to maintain. And the signal is binary, not relative: You can only say “these two phones came very close” instead of “this phone was 6 feet from that phone”. That raises the concern that many of the proximity events recorded by our phones will be false positives – cases where you were relatively close to someone who reported an infection but may not have been close enough to infect yourself.

Apple says it is still investigating all of this but notes that public health apps may include the duration of proximity when deciding what counts as a proximity event. (The suggested time I heard today was five minutes.) Within a five-minute interval, you would be less likely to shoot false positives from someone jogging on the street for you.

Which begs the question, what are the circumstances during the pandemic when people are (1) within 30 feet of you, for (2) five minutes or more, that (3) you don’t know? (If I knew them well, I’d probably also discover they had COVID-19.) Some suggestions I’ve heard today: supermarket workers; people waiting in long lines for things (like the entrance to grocery stores); warehouse workers; and public transportation. As cities begin to reopen, more use cases may emerge. But it appears that a passive system that works to inform people in those situations of possible exposures could offer at least some level of protection. The question is if the system generates more signal than noise, if Bluetooth finds more true positives than false.

We’ll see.
Finally, is Silicon Valley relying too heavily on untested software solutions when a proven manual solution might suffice? That’s the argument in an article this week from the Margolis Center for Health Policy at Duke University. Authors Mark McClellan, Scott Gottlieb, Farzad Mostashari, Caitlin Rivers, and Lauren Silvis write:

Ideally, when a new case of COVID-19 is identified, local public health officials will ensure that the affected individual is isolated, and that their close contacts are identified and asked to be quarantined. However, the existing local public health capacity for such response activities is very limited, and many jurisdictions have abandoned contact tracing in favor of mitigation measures at the community level. To allow a return to case-based interventions as incidence decreases, these capacities must be expanded. Enhanced capacity will be more effective if coordinated with health care providers, health systems, and health plans and supported through timely electronic data exchange. Cell phone-based applications that record proximity events between individuals are unlikely to have adequate discrimination capacity or adoption to achieve public health utility, while posing serious privacy, security and logistics concerns. Instead, timely follow-up of contacts can be achieved through strengthened public health case research augmented by technology and collaborations at the community level.

But other researchers have argued that COVID-19 simply spreads too easily for manual contact tracing to be a feasible solution to the problem. Something passive and automated is needed to counter the transmission rate, according to a March article in Science. Luca Ferretti, Chris Wymant, Michelle Kendall, Lele Zhao, Anel Nurtay, Lucie Abeler-Dörner, Michael Parker, David Bonsall and Christophe Fraser write:

Traditional manual contact locating procedures are not fast enough for the SARS-CoV-2. However, a delay from confirming a case to finding your contacts is not inevitable. Specifically, this delay can be avoided by using a mobile phone app.

Perhaps the best way to think about the Apple/Google announcement is that in a world without a coherent federal response to the ongoing disaster, we must rely on a patchwork of partial solutions. In such a world, I have no objection to Apple and Google trying to create contact tracking, even if I’m concerned that people expect too much of it. I am also, as always, open to being pleasantly surprised.

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