Contact tracing — until this year a process familiar mainly to epidemiologists — is elegant in its simplicity.

Or so it seemed.

The idea is to track the spread of communicable diseases by interviewing people who may be infected and find out who they have had close contact with and thus might have spread the disease to.

In some cases the potential infectious encounter is obvious — a person who tests positive spends a couple of days in a small house with a group of friends.

But the limitations of contact tracing have become apparent in Oregon during the coronavirus pandemic. For much of this summer, contact tracers haven’t been able to determine the source of infection for more than 40% of Oregonians who tested positive. The rate of “mystery” infections recently is even higher in some counties, including 62% in Multnomah County, the state’s most populous, and 67% in Clackamas, which ranks third in population, according to The Oregonian.

A potential reason for this level of uncertainty is the limited nature of contact tracer interviews. Oregon Public Broadcasting and The Oregonian recently reported that contact tracers aren’t asking people who tested positive for COVID-19 whether they’ve patronized a bar, restaurant or gym during the period when they might have been infectious.

Health officials from Multnomah County told The Oregonian this question isn’t part of contact tracing interviews because there aren’t enough tracers to track potential infections based on places the infected person visited, and the primary goal is to identify people who might have been in close contact with an infected person. Those people are then asked to voluntarily quarantine during the period when they might be infectious.

But even if health agencies don’t have resources to backtrack every infected person’s movements, conducting more thorough contact tracing interviews would at a minimum yield additional data. And if ever there was a situation when more information is welcome, surely the coronavirus pandemic is that situation.

The purpose isn’t to target bars, restaurants and gyms, many of which have been devastated financially during the pandemic. The Oregon Health Authority hasn’t reported any COVID-19 outbreaks at a bar or gym, and the agency has announced just six relatively small outbreaks at restaurants, involving five to 14 infections. But the OHA limits disclosure of such outbreaks — it doesn’t announce ones involving fewer than five people or ones at businesses that employ fewer than 30.

But the OHA is unlikely to reveal latent infection patterns if contact tracers aren’t asking possibly relevant questions. Responses to those questions, besides the obvious benefit of potentially identifying sources of community spread and making it possible to deal with those sources, could help businesses by alerting them to potential gaps in their COVID-19 precautions.

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