Does Phone Contact Tracing Actually Work?

It is, at best, a supplement to traditional methods of contact-tracing by teams of people.

Even in smaller, more authoritarian countries than the US and UK, too few people have downloaded the apps for them to provide anything more than ancillary information. JL

Shirin Ghaffary reports in Re/code:

Tech-based efforts have been underway for months in Singapore, China, and Taiwan, where Covid-19 hit earlier than in the US. What works in one country won’t necessarily work in the US. For any technological contact-tracing tool to work, it has to have a high percentage of the country using it.  Singapore said it would need two-thirds of the population using it. As of April 1, only 12% of people in Singapore opted to download the contact-tracing app. For these notifications to be of any use, people need access to proper testing, health care systems, and financial support.

If and when lockdown restrictions are lifted in the US, would you agree to let the government anonymously track your interactions with people within a 6-foot radius to control the spread of Covid-19?

That’s an increasingly urgent question as President Trump and state governors debate how and when to safely reopen the US economy — and as technology is being touted as a solution that would help people reenter public life.

And tech giants are stepping up. Last week, Apple and Google announced a plan to turn phones into opt-in Covid-19 tracking machines that would, if all goes as planned, make it easier for health officials to identify and alert people if they’ve been exposed to the virus.

The idea is familiar because similar tech-based efforts have been underway for weeks and even months in countries like Singapore, China, and Taiwan, where Covid-19 hit earlier than in the US.

But what works in one country won’t necessarily work in the US. Some of these Covid-19 tracking technologies — like mandatory electronic wristbands in Hong Kong that tip off authorities when people under quarantine leave their homes — seem implausible in the US, where for years civil rights advocates have fought to protect people’s online privacy and push back against government surveillance. Apple and Google’s system is being designed to protect the identities of people who use it, but concerns abound that outside parties (including the US government itself) could try to de-anonymize that data.

The stakes are incredibly high for these tools. If they work as intended, they could help end a once-in-a-lifetime public health crisis. But if ineffective, they could provide a false sense of confidence in our abilities to control the virus and allow it to spread further. On top of all that, even if these tech solutions successfully slow Covid-19’s spread in the US, they pose serious, yet-to-be-determined risks to Americans’ privacy. With all that in mind, here’s what we can learn from other countries’ tech-based responses to the coronavirus as the US develops its own.

Technology can help, but it’s just one part of an effective strategy

One of the main ways technology can help stop the spread of the coronavirus is with digital contact tracing, which is the process of identifying people who may have come into contact with the virus.

Traditionally, contact tracing has required human involvement. When someone tests positive for the virus, public health investigators get in touch with them, learn about everyone they’ve been in contact within a certain time frame, and then manually track down and notify all those contacts.

Digital contact tracing automates a part of this process by relying on people’s phones to map out their ongoing web of physical interactions. The Apple-Google system will use a smartphone’s Bluetooth signal to create a log of the people the phone’s user has come into close proximity with, while keeping people’s identities and locations anonymous. As Recode previously described, “It works a bit like exchanging contact information with everyone you meet, except everything is designed to be anonymous and automatic.”

This type of contact-tracing technology is already helping contain the spread of Covid-19 in countries like Singapore and Taiwan — but it has limitations.

“Technology is not a silver bullet, but one way to get information,” said Anne Liu, a global health public health expert at Columbia University who worked on efforts to digitize information collected from patients during the Ebola epidemic. With that caveat, Liu went on to say of the new public health technologies we’re seeing in East Asian countries, “I do think some of this can be especially promising for something that’s moving at the speed that Covid-19 is moving.”

Take Singapore. The country attracted praise early in the pandemic for its initial success at curbing the spread of the virus. In March, the country released TraceTogether, an app that uses Bluetooth technology to help public health officials do contact tracing. Much like the Apple-Google tool, Singapore’s app automated the process of tracking down every person a given person came into contact within a two-week period. It works by allowing users to log in the app if they test positive for Covid-19 and the tool then anonymously notifies everyone they’ve recently seen.

While the TraceTogether app is one important part of Singapore’s overall solution, it’s only a supplement to a broader, intense series of policy interventions. Those include shutting its borders to Chinese travelers in early February, banning large-scale gatherings, imposing quarantine measures, and mobilizing a team of dedicated contact tracers to investigate cases manually. Despite all this, the country’s government is still grappling with containing a recent resurgence in new cases.

It’s hard to say yet if the app made a significant dent in improving public health. As of April 1, only 12 percent of people in Singapore had opted to download the contact-tracing app. One of the key government officials helping release this app explained these limitations of the technology and made the case for governments to continue investing in human beings to do manual contact tracing in addition to any tools they’re rolling out.

“If you ask me whether any Bluetooth contact-tracing system deployed or under development anywhere in the world is ready to replace manual contact tracing, I will say, without qualification, that the answer is, ‘No,’” Jason Bay, the product lead for TraceTogether, Singapore’s nationwide Bluetooth contact-tracing system, wrote in a blog post on Friday.

Singapore’s experience suggests that even if there’s widespread adoption of Apple and Google’s contact-tracing tools when they are released, there are limits to their effectiveness.

There are privacy trade-offs

In the US, mandatory app-based contact tracing isn’t on the table for now. But in other countries, digital health-tracking is essentially government mandated. And any time technology pulls people’s health data — especially without their input — it poses serious privacy concerns.

China is an example of what is at stake. The country’s government has long employed technology like facial recognition to control the activity of its citizens, including to target ethnic minorities. Now, in response to the pandemic, it is partnering with major tech companies to expand that mass digital surveillance network and tie it to people’s health data.

As the spread of Covid-19 in China began to slow down in mid-February, local governments (outside of Wuhan, where the virus originated) began lifting strict lockdown orders. Soon after, private companies — in partnership with the Chinese government agencies — began rolling out app add-ons that help the government determine who can start safely leaving their house again without infecting others.

Now, before people can do things like ride the subway or enter a crowded shopping mall, they have to prove they’re at low risk of having Covid-19. They do that by scanning a government-mandated QR “health code” on their cellphone that’s either green (likely Covid-19 free), yellow (at risk of Covid-19), or red (likely Covid-19 positive).

It’s not known exactly how the code is calculated, but it’s loosely based on information like a user’s location and their medical and travel history, which is informed in part by a government questionnaire. Tested positive for Covid-19 or have recently traveled to Wuhan? You’re in the red. Healthy and no travel to high-risk areas? You’re in the green.

Currently, people generate these codes in Alipay and WeChat, which are mega-apps in China that nearly every citizen has installed on their phones and that they use to do everything from chatting to buying basic goods to hailing rides.

And in South Korea, the government hasn’t issued people with QR health codes, but it is broadcasting detailed information about infected people’s whereabouts. When someone in South Korea tests positive for Covid-19, government health authorities send regional text alerts, notifying residents that someone near them has the disease and linking to a central website with more information. While the government doesn’t share people’s names, it does provide details on the website, such as the person’s age range, gender, and places they recently visited — which has led people to publicly speculate about their neighbors’ marital affairs and other private matters. Some have argued that this could lead to stigma around being tested for the virus and discourage people from doing so.

The contact-tracing system Google and Apple are working on is notably more privacy-centric than the methods we’re seeing in China or South Korea, but it still poses concerns. The two companies have now committed to shutting down the tool once the pandemic is over — which was a key issue for many privacy experts — but other concerns abound. There are still ways that even the randomly generated Bluetooth keys meant to anonymize users could be linked back to real identities.

Apple and Google are also leaving it up to public health authorities to develop and manage the apps that will use their contact tracing tool. It’s conceivable that those authorities could introduce their own ways to circumvent privacy protections if their governments so desire. The UK’s National Health Service, it was recently reported, was looking into ways to identify users of a contact-tracing app it was developing. In the US, Sen. Richard Blumenthal, who is typically on the side of pro-privacy legislation, has already asked Apple and Google how the companies will assure users that the tool protects their privacy. That said, the tool ticked off many of the American Civil Liberty Union’s boxes for what a privacy-friendly contact-tracing tool must do.

People need to use it for it to be effective

For any technological contact-tracing tool to work, it has to have a high percentage of the country using it.

But just how high? Experts aren’t sure yet. A Singapore government official working on the country’s contact-tracing app said it would need to see something like two-thirds of the population or more using it. One researcher at Oxford University who has been modeling the effects of digital contact tracing apps told the Wall Street Journal that you need about 60 percent of the population to opt in for such a tool to be effective. In a press call last week, Apple and Google cited that Oxford research and a similar range for their system to potentially be effective.

In China, health-tracking digital QR codes are used by wide swaths of the population. In the Zheijang province, which is home to 50 million people, the local government says about 90 percent of residents signed up for a code. Of course, that’s because those apps are all but necessary to get around and do basic day-to-day activities like go to work, enter the market, or ride public transit.

In countries where the apps are opt-in rather than mandatory, we’re not seeing adoption rates nearly that high yet.

This raises questions about how the US will be able to convince enough people to download the app, as compared to China’s more mandatory enforcement.

What happens after people are notified of exposure makes a difference

Having an app tell you you’ve been exposed to Covid-19 is helpful, but it’s only the first step we’re seeing in effective international responses to controlling the pandemic.

For these notifications to be of any use, people need access to proper testing, health care systems, and financial support to get through a period of quarantine and potential illness, public health experts cautioned. If you don’t have that, you risk social unrest.

South Korea, for example, had early success flattening its curve thanks to aggressive testing that has been free of cost to its citizens. It also pioneered the drive-through testing model that other countries like the US have followed.

But access to these resources may be harder to roll out at scale in the US, where there’s still a shortage of tests and delays in lab processing, and where health care systems in hot spots such as New York City are overwhelmed. The US has surpassed South Korea in the total number of tests, but adjusted for population, has tested at just 74 percent of the rate of South Korea.

Apple and Google say that in their digital contact-tracing system, once someone is notified they may have been exposed to Covid-19, they’ll receive a message urging them to get tested and self-quarantine. But being cautioned to get tested is one thing; actually having easy access to a test is another.

“If you start coming into contact with someone Covid-19-positive, what is the ability for someone to be evaluated and also tested?” said Dr. Andrew Chan, a professor of immunology and infectious disease at the Harvard T.H. Chan School of Public Health. “Contact tracing won’t be helpful in and of itself if we can’t act on the information we gather.”

Chan recently helped create a mobile app that helps people self-report and track Covid-19 symptoms. The app has been used to confirm previously unknown symptoms of the disease, such as loss of smell and taste, and to understand where the disease is spreading without relying on people getting tested. He said he’s hopeful about the US implementing new technologies around contact tracing but emphasized the need for public health agencies to provide adequate resources to follow up on this new data.

What happens next

Extensive contact tracing is less useful in a region that’s in the middle of an outbreak — like New York and California — where there’s widespread community transmission and people are already sheltering in place in their homes.

But, in the future, when the number of cases in those states eventually declines and when businesses begin to reopen, contact tracing can help people safely reenter society. If someone is deemed high-risk because of exposure to an anonymous contact, they would stay at home for two weeks before they go back to the office or anywhere outside their home.

With contact tracing like that, Liu said, “you can do more of a targeted quarantine, because it can target who to keep in quarantine rather than everyone,” said Liu. “Once you have the contacts [of someone who is diagnosed with Covid-19], then you know who should go into quarantine.”

That’s happening by force in places like Taiwan, where most people are free to go to work, restaurants, and public places. But for the tens of thousands of people in Taiwan who are under quarantine, the government is “geofencing” them in their homes by tracking their cellphone signals and using police enforcement. China has a similar approach: If your QR health code is red, you have to stay put in your home.

But no system is absolutely effective, and it’s plausible to see a world where the US adapts certain parts of different countries’ strategies to use technology to reopen the economy.

New technology will only help if it’s complemented by sound policy and swift leadership, two things President Trump’s administration has botched, with disastrous consequences. Successfully using new technology will also require open-mindedness and cooperation between the private and public sectors — without violating people’s basic rights to privacy.

And it’s not just the US that faces this challenge. Places outside Asia, such as the UK, Australia, and Iceland, are all considering using similar digital contact-tracing tools, and they face the same policy challenges. It’s an unprecedented task for an unprecedented time — but taking into consideration what other countries’ methods are working well, and with what consequences, can help US leaders better understand how to create a system that may work for everyone.