Case Tracking Readiness

Readiness to begin the Reopen depends on meeting two main criteria: viral reproduction rate (Rt) below 1.0; and the capability for identifying new cases, quarantining them, and tracing their contacts. A number of US states are approaching readiness on Rt; it’s the ability to track individual cases that’s presently in question.

Maintaining the lockdown until the initial wave peters out and Rt gradually drops to zero? Moneyed interests are getting antsy, and ending the first wave won’t prevent new waves from forming. Gradually relax social isolation without the intensive case tracking? That road leads to herd immunity, but at the cost of overburdening the medical system and racking up high body counts — deaths that could be prevented if a low Rt can be sustained until a vaccine becomes widely available. Only by achieving twofold readiness can states restore some semblance of economic and social normalcy while avoiding mass casualties.

The state of Washington offers an intriguing case study. Washington was an early hotspot, but since imposing its social distancing orders the state has seen its daily new diagnoses drop slowly but consistently since the beginning of April. Now the governor has announced the formation of a contact tracing brigade. The state plans to have 1,500 tracers in place and trained by the second week of May. Relying mostly on tech and telephone, the tracers expect to be able to contact 7 new cases and 21 social contacts daily.

Is that enough? Over the past week Washington has averaged about 200 newly diagnosed cases per day. If other estimates of undercounting apply to Washington, then the actual number of newly infected individuals is more like 10,000 per day. 1500 tracers x 7 new cases per day = 10,500 daily traces: right on.

Will it work? The state acknowledges that a lot of people don’t answer phone calls from numbers they don’t recognize, which in our experience can nearly all be traced to direct marketing bots. And it’s not clear how effective a telephone-based reminder to self-isolate will prove to be. The tracers will check back periodically on their caseload, offering encouragement, support, and information about useful resources available to the self-quarantined. Washington has been very efficient in managing the spike in new unemployment claims, so that’s removed a significant obstacle to maintaining shelter-at-home. Obviously the tracers can’t assure their working clients that they’ll receive sick pay while in quarantine — that’s up to the employers.

Ultimately, officials say none of this will work until coronavirus tests become more available. There’s little point in warning people they’ve been in contact with an infected person if they can’t get tested. Gov. Inslee says Washington’s contact tracing plan will require between 20,000 and 30,000 tests a day. At the moment, the state can’t do more than 4,000, and on Tuesday he sent a letter to Vice President Pence repeating his calls for more federal help to ramp up the supply.




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