Under siege from the novel coronavirus and looking to catch up, the Trump administration is reportedly discussing cellphone location-tracking to understand the spread of the outbreak. But epidemiologists say that U.S. public health officials may have missed their chance for their chief surveillance tool, a method known as contact tracing, to make a difference.

“To try to do contact tracing on thousands on thousands of people is like trying to do the census in a couple hours,” explained Michael Osterholm of the University of Minnesota’s Center for Infectious Disease Research and Policy, a leading pandemic expert.

Coronavirus surveillance isn’t like the kind of surveillance used to track, say, terrorist suspects. Public health officials seeking to arrest an outbreak start with a positive test of a patient and then work outward to find and warn people the patient was in close contact with. Counterterrorism surveillance, in practice, tends to gather everyone’s data first—often without warrants—analyze it for connections to targets of interest (a practice known as contact chaining), and then either purge it or keep it.

Still, COVID-19 surveillance can be deeply intrusive. In South Korea, where a democratic country flattened the rate of the outbreak’s growth, authorities retraced the physical steps of those who tested positive. They enlisted credit card records for purchase patterns, GPS data for travel patterns, and security-camera footage for verification. Surveillance in data-dystopian countries like China was far more extensive. Beijing mandated the installation of tracking apps on people’s phones that shared data with police.

But according to epidemiologists, America is unlikely to replicate South Korea’s success. South Korea (and China) tested extensively for COVID-19 early on. That was the key step for being able to identify and isolate those infected before they spread the disease further. No such thing occurred in the U.S.—and accordingly, domestic pandemic surveillance in late March 2020 would resemble the anticipatory guesswork of counterterrorism surveillance, more intrusive than effective.

In areas like New York or Washington state, where COVID-19 is already highly prevalent, Osterholm said the spread of the outbreak ahead of widespread testing means the window for contact tracing is functionally closed. The window’s still open in places around the country where the virus is less widespread, he said—but only for a matter of weeks.

“The availability of reagents, the chemicals you need to do the tests, is about to hit a wall. The whole world wants these reagents at the same time, and we just never created the kind of production capacity,” Osterholm said. “Bottom line, you have a limited use of this [contact tracing], in low-prevalence areas, and you’re running against a lack of availability.”

Arnold Monto, a professor of epidemiology at the University of Michigan’s School of Public Health, said “we’re beyond” what contact tracing can offer.

“We have community-level transmission nearly everywhere now. Contact tracing is not going to contribute when you’re seeing mild cases going undiagnosed without the ability to test,” Monto said. “Even in some rural areas, you’re having cases.”

For counties that still have few known cases, contact tracing can still make a difference, said Jeffrey Klausner, an epidemiologist at UCLA. The problem is the public health infrastructure is so overloaded that Klausner thinks it ought to be offloaded to patients or relatives calling people in close contact to alert them to the risk—basically, as someone would tell their sex partners when they learn they’ve contracted a sexually transmitted disease.

People with COVID-19 symptoms “probably know who’s been exposed, and they should contact them. We should unburden the public health care system and do what we call task-shift,” Klausner said. He advocated following the model of an STD site, TellYourPartner.org, that provides information and resources for people who may be exposed to COVID-19.

The Centers for Disease Control noted the limits of contact tracing in February.

On Feb. 12, the CDC mandated the airlines collect and on request provide lists of names, addresses, phone numbers and email addresses of passengers arriving in the U.S. from overseas. Its rule change was predicated on contact tracing, something the CDC warned was perishable.

“Contact tracing is effective at reducing cases of communicable disease at the early stages of a potential outbreak if the contacts are notified as soon after initial exposure as possible,” the CDC said in a notice to the Federal Register. “If an efficient contact system is not in place when the first ill passengers arrive, the benefits of the contact tracing are greatly diminished.”

It isn’t clear what the CDC has done with any data it acquired under the rule change. The agency didn’t respond to a request from The Daily Beast.

The Washington Post recently reported that the Trump administration is discussing phone-data tracking for COVID-19 contact tracing with tech firms—notwithstanding epidemiologists’ assessment that it’s largely too late. On Capitol Hill, legislation rolled out earlier this week did not contain expanded mandates for data exploitation or repurposing the intelligence agencies’ massive national-security data troves to track the virus. But the latest version, released Wednesday afternoon, mandated the CDC to rapidly construct “a public health surveillance and data-collection system for coronavirus,” and authorized $500 million for “public health data surveillance and analytics infrastructure modernization.”

What polling exists on coronavirus surveillance shows strong opposition: 57 percent registered opposition to the reported administration discussion about geolocation data acquisition.

For their part, the security agencies are cryptic when asked if they’ve changed any exercise of their surveillance authorities for addressing COVID-19.

An FBI official said the bureau was in regular contact with the CDC and other relevant federal agencies, and is “taking a comprehensive approach to prepare for a variety of scenarios.” An official with the Office of the Director of National Intelligence said ODNI “continues to monitor the COVID-19 pandemic and adjust its response.” Neither would elaborate and preferred instead to detail measures taken to protect their workforces.

Michelle Richardson, director of the Center for Democracy and Technology’s Privacy and Data Project, warned that any surveillance expansion predicated on an emergency like the pandemic outbreak was likely to become permanent and repurposed.

“That’s what’s so scary about this,” Richardson said. “An epidemic today; tomorrow, everything from immigration enforcement and criminal investigations.”

“What’s happening now is exponential growth in surveillance capabilities, colonizing a crisis as power always does,” observed Shoshana Zuboff, a professor emerita at Harvard Business School and author of the recent book The Age of Surveillance Capitalism. “We should be able to have the public health system evolving in more sophisticated ways, always under the rule of law, and the rule of law stands as legitimated by democratic institutions. This has to be the structure if we are to survive as a democracy.”

Contact tracing is a mitigation and containment tool, one that can aid in slowing the spread of the virus while giving overtaxed hospitals a bit of breathing room. Monto said self-quarantining held the best chance at replicating what contact tracing can offer.

“We’re hitting a point,” Osterholm said, “ where there’s really two types of people in the world: people who are in quarantine and those who will be.”

—with additional reporting by Olivia Messer