The CDC is talking about contact tracing again. Robert Redfield recently described for National Public Radio a renewed effort to quell the COVID-19 epidemic (Simmons-Duffin & Stein, 2020). In three words, he illustrated it as 'Block and Tackle'.

Morning Edition doesn't stream pictures through the radio, so the CDC director's name conjures up the image of a golden-haired actor. Instead, Dr. Robert rocks an Amish-looking beard while doing his best to signal a proactive federal agency. He's gonna have to work hard to convince - today's CDC apparently dropped the ball on COVID-19. The CDC of last century might have done better.

The Centers for Disease Control and Prevention began its patchwork set of directives in 1946 (Wikipedia contributors, 2020). It started as a nationalized effort to fight malaria, and gradually morphed into a catch-all epidemiology headquarters. In the 1950's the Cold War gained momentum with its hydra of many threats – biological warfare was one of them. In an effort to address this threat, the CDC employed an investigative core called the Epidemic Intelligence Service.

Interestingly, many of EIS' investigations identified U.S. businesses - instead of the nefarious Communist Russia - as the culprits of contagion.

In those days the CDC was more about numbers and boots on the ground than it is today. Like other government agencies of its period, it generated solutions with a rigorous and documented effort conducted by large teams of people. In our generation of computers and robots, we usually look first to some clever algorithm or efficient logistical approach. But problem-solving for an epidemic is more of a ‘Tower of Hanoi’ than a ‘Quicksort’ – we must investigate each case as it appears. This is contact tracing in a nutshell.

Contact tracing is an enduring strategy in the tradition of rigor. An investigator interviews an infected person and asks a few questions:

• When did you first show symptoms?
• Who were you in contact with before that time?
• Who were you in contact after that time?

The interview can be more detailed than that, but the goal remains the same: Find anyone who might be infected by tracing each contact from a known infected person. That sounds simple, and on paper it really is. In practice, however, it's difficult. To be effective contact tracing requires sedulous operation, communication and travel. The investigator must make the effort to interview each contact by any means, and this includes visiting a contact's current location if necessary.

It also requires mobilization of a lot of people - something government organizations are usually good at. The Associated Press reported a deployment of about 9,000 health workers by China -- to Wuhan alone (Cheng, 2020). In the case of COVID-19, the people requirement is higher to allow for tracing even potentially infected contacts. (This is because we have neither reliable testing, nor a defined virulence window prior to symptoms (Bedford, et al., 2020).) So, why didn't the CDC follow through with this strategy from the beginning?

Redfield implies the problem is one of manpower - we just don't have it. He points to the CDC's current field staff of 600 people. That is terribly small for a nationwide contact tracing effort, and Redfield knows this. As a scientist and a leader, it's expected that he always knew this. Furthermore, it's a matter of public record that we all should have known (Brannen & Hicks, 2020).

The Pentagon knew about this exact problem in 2017, when they did a study and issued a report on the potential of a catastrophic influenza epidemic (Slotkin, 2020). We knew what the problem would be, and we knew exactly how to solve it. We just didn't.

The most likely reason we failed to safeguard the United States from the pandemic is the usual suspect: money. It's fine to say that an epidemic requires an army of investigators to run contact tracing. However, those investigators must be hired and paid. And when the epidemic ends, they can’t be kept on the payroll - they would be bored, and we would be broke.

The conundrum can ostensibly be circumvented by technology. Singapore, for example, deployed an app (Osorio, 2020). However, the app depends on self-reporting, which can involve poor or faulty memory and inconsistent use.

Some countries, like South Korea, employed surveillance and personal data mining. But this can be an itchy subject in the U.S., where personal privacy overlaps with constitutional freedom. Furthermore, freedom of speech almost always becomes threatened when power meets digital surveillance. Before this nation can seek such electronic methods, it behooves us to establish a digital bill of rights.

Until that day comes, we must settle for the boots on the ground. And in the case of future epidemics like COVID-19, we need to employ a strategy of assuming positive cases when the symptoms and risk of infection are commensurate (Ferreti, et al., 2020).

Here are two examples of this:

1. Patient interviewed in hospital has severe symptoms and has likelihood of passing near a previous contact while contagious: Investigator assumes transmission occurred.
2. Person interviewed does not show obvious symptoms but has high likelihood of proximity to previous contact. Investigator assumes transmission occurred.

In both cases, no test is available. The necessity to quarantine and observe suspected cases is based on the two concerns that the virus can be communicated prior to symptoms and that disease can escalate rapidly.

We can still employ modern algorithms and models like this one (Niehus, et al., 2020) to improve planning and allocation of resources. No matter what, though, the only thing that gets the job done is people, planning and persistence.