With all the focus on apps and other high-tech means of investigating potential COVID-19 exposures, one could be forgiven for thinking that contact tracing was a modern innovation.
Far from it; in fact, use of contact tracing goes back to at least the 16th century when transmission of diseases like syphilis and plague were studied using what we would identify today as contact tracing. In the case of bubonic plague, results of contact tracing were used to debunk theories that the disease was the result of bad food, pollution or even of a celestial origin.
Evidence of contact tracing can be found in a German hospital register compiled between 1500 and 1700 that includes, for every patient seeking treatment, an explanation of the conditions that led to them contracting whatever illness they were sick with. This included how and, when possible, from whom they got the illness.
Many health researchers and leaders point to contact tracing as a means of controlling the spread of the novel coronavirus, so how does contact tracing work and what can we learn from other times when it’s been used to curb disease rates?
The Basics of Contact Tracing
Contact tracing essentially is medical detective work in which contact tracers, often working for state and local health departments, identify individuals who may have been exposed to an infectious disease. Those who were possibly exposed are then connected with health resources to get tested and, if necessary, treated so that the disease cycle is broken.
Perhaps the most common use of contact tracing for public health in the U.S. today is in combating the spread of sexually transmitted infections (STIs). More than 1,600 specialists are funded by the Centers for Disease Control and Prevention to investigate positive cases and identify individuals who may have been unknowingly exposed to a range of STIs, including syphilis, chlamydia and gonorrhea. These professionals work in state and local health departments, and such individuals have been deployed across the United States since the 1940s, when the role of disease intervention specialist was established to combat a huge surge in STIs.
Syphilis, in particular, had become quite prominent during and after World War II, and almost 200,000 Americans were diagnosed with the early stages of the disease, which if left untreated, can be fatal, in 1946 and 1947. By the next decade, cases and rates had plummeted, due in large part to adoption of contact tracing.
Contact tracing has been used widely in the U.S. to prevent the spread of other diseases, including influenza, Ebola, Zika, HIV and tuberculosis. There’s scant data on the efficacy of contact tracing for most of these diseases, as virtually every infection for which it’s been used is different, with varying infectiousness levels and incubation periods.
Contact Tracing & COVID-19
Contact tracing is being used already in many places around the world to combat coronavirus, including here in the United States, though other places have embraced the practice more fully as part of a portfolio of methods to reduce COVID-19 infection rates.
A recent study in the United Kingdom found that contact tracing was dramatically more effective than other means of curbing COVID-19 infections, including mass random testing, self-isolation and other methods.
Contact triggers for COVID-19 vary, but in general, for every positive test, an effort is made to contact (and possibly test) anybody who had contact with the infected person within a radius of 6 feet for more than 15 minutes (it’s 10 minutes in some places, including Michigan) within a couple of days of the onset of symptoms. Here’s a look at a possible sequence of events in COVID-19 contact tracing:
The process then continues, though often without the intervention of a contact tracing specialist. For example, household members or coworkers of a person who had contact with an infected individual may pursue testing and contact tracing on their own.
Robust contact tracing is one of the most important tools Germany has used to control the pandemic in that country, where about 400 call centers are in operation allowing Germans to quickly connect with contact tracers and medical support personnel. Leaders have said their goal is to have one tracer per 4,000 people, or about 21,000 contact tracers for the nation of 83 million.
Too Little, Too Late?
Whether the United States could follow the German model of using an effective contact tracing strategy remains to be seen, but already many states, cities and counties are adopting the practice. Still, the summer resurgence of the virus after states relaxed rules regarding business reopening could overwhelm the system.
Alabama, California, Missouri, Rhode Island, Tennessee, Utah, Washington and West Virginia and more all have announced plans to hire or reassign local and state government employees, including National Guard personnel, to the task of contact tracing. Still other states have said they plan to contract with outside vendors for this service, including Indiana, Maryland, Massachusetts and Ohio, while other states and counties are seeking volunteers. But the patchwork of plans for contact tracing means there’s no one national plan for utilizing this tool to fight COVID-19.
Contact tracer shortage
There’s no doubt that a shortage of tracers is already in evidence. An NPR analysis in May found that 44 states and D.C. planned to add contact tracing employees to the tune of more than 66,000 workers. But other estimates have indicated that the U.S. needs to increase the contact tracing workforce by more than 180,000 until a vaccine becomes available.
NPR’s analysis indicated that 30 contact tracers per 100,000 residents would be needed for the COVID-19 pandemic and only a handful of states were on track to meet that need. This number is roughly equivalent to the ratio employed by German health officials.
Widespread nature of virus
To be sure, some states had a better handle on the spread of the virus through the late summer. But in states where the virus is widespread, contact tracing will be less effective because it will be much more difficult to pinpoint infection sources.
Time will tell the toll of coronavirus, both human and otherwise, but evidence has consistently suggested that contact tracing should be fully embraced as a strategy for curbing the spread of the virus, and there’s no doubt that some states are planning to invest more heavily in ramping up their use of contact tracing than others. But with a possible vaccine likely at least several months away, towns, cities, counties and states still have time to show they are taking the COVID-19 threat seriously by implementing robust contact tracing measures that might cut off the supply of oxygen to this virus.
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