Every strategy for releasing Covid-19’s vise-grip on daily life starts with identifying cases and tracing their contacts — the laborious task of public health workers tracking down people who have crossed paths with a newly diagnosed patient, so they can be quarantined well before they show symptoms.
That typically takes three days per new case, an insurmountable hurdle in the U.S., with its low numbers of public health workers and tens of thousands of new cases every day. Existing digital tools, however, using cellphone location data and an app for self-reporting positive test results, could make the impossible possible, the authors of a new analysis argue.
“Traditional manual contact tracing procedures are not fast enough for [the new coronavirus],” researchers at the University of Oxford write in a paper in the journal Science this week. But digital technology“can make contact tracing and notification instantaneous.”
The “technology to the rescue” idea has been gaining steam as the coronavirus pandemic has outpaced everything Europe and the U.S. have thrown at it, and not because of a deluded belief that digital tech can solve all the world’s woes. Instead, this fix is aimed at a very specific problem: identifying cases of Covid-19 and quickly tracing everyone who came into contact with them before they infect others. That has helped countries such as South Korea, Taiwan, and Singapore beat back the epidemic, though sometimes through measures that trample privacy.
“We have evidence that this works,” said computational epidemiologist Maia Majumder of Boston Children’s Hospital, referring to contact tracing and case isolation. “The public health consensus is clear that this is what we need to do.”
The U.S. and Europe have hardly attempted contact tracing, however. It requires an army of public health workers or intrusive policies that many of their citizens oppose. But this week brought efforts to circumvent both obstacles.
One high-profile effort is led by Trevor Bedford, an infectious disease modeler and genomics expert at the Fred Hutchinson Cancer Research Center in Seattle. This week, he and his colleagues launched “NextTrace,” a project based on the fact that traditional contact tracing doesn’t scale: With more than 200,000 cases in the U.S., and each case requiring hours of detailed follow-up, doing this by analog methods won’t work.
“So much of this virus’s transmission, maybe 15% of total cases, is from people who don’t feel sick,” said mathematical biologist Lauren Ancel Meyers of the University of Texas at Austin, who is advising NextTrace. “And it’s spreading so quickly, with as few as four days from when one person shows symptoms to when people he infects does. It would therefore take a heroic effort and very fast quarantine and isolation to identify, by traditional methods, every person who’s infected, and every person they contact, and everyone they contact.”
NextTrace therefore plans to build a decentralized reporting system in which anyone with confirmed Covid-19 can choose to register, anonymously, on an online platform. The platform will use cell phone location and proximity data from cellphones, for people who have opted in, to find individuals who might have been exposed to this case and advise them to be tested. The system would build a contact history for each case.
Exposed individuals can be tested and, if infected, isolated. The earlier that happens the more transmission drops: People shed the highest level of virus soon after symptoms appear, scientists in Germany reported on Wednesday in the journal Nature.
