By Margaret Battin, Leslie Francis, Jay Jacobson, and Charles Smith
What if, instead of closing airports, shutting down trains and buses, quarantining travelers from China, and enclosing 50 million people inside the city of Wuhan and Hubei province, we had a sophisticated technology that could identify travelers who might spread an emerging infectious disease? This question is not hypothetical. We do have an available technology: polymerase chain reaction (PCR) rapid testing, one among several forms of nucleic acid amplification technology.
But PCR rapid testing has been deployed imperfectly at best, especially in the United States. The initial case of what is thought to have been community transmission in the United States was not tested for several days. The result was preventable exposures to infection of health care workers and potentially others. Testing criteria were set very narrowly. Rapid test kits designed by CDC did not work successfully because of problems with one of the reagents. On February 29, the FDA issued guidance allowing laboratories CLIA-certified for high complexity testing to use tests they had developed and validated before receiving emergency use approval.
Although the situation is changing almost hourly, and much is still unknown about COVID-19 and its transmission, we do know the importance of identifying cases early. We also need to be thinking about the ethical issues raised by rapid testing: by the failures of preparedness, the inadequacy of deployment, and deployment itself.
So suppose that when you show up at the airport, in addition to presenting your passport and your ticket and surrendering your luggage for security inspection, you get a throat or a nasal swab. You rub it at the top of your throat or inside your nose; it is fed into an analyzer to scan for the distinctive genetic signature of this particular coronavirus. Meanwhile, as you prepare to board the plane, your result is processed and relayed to your gate. If you’re negative, you are on your way; if rapid testing identifies COVID-19, public health authorities will take over your care and contact those whom you might have exposed.
This scrutiny applies to everybody: passengers, pilots, cabin crew, and the cleaning service. Nobody boards a plane with an infectious disease they could transmit to others, either on the plane or after it lands. Instead of quarantining off an entire city, the same technology could be used at other places of public contact: train stations, ship terminals, subway systems, stadiums, hospitals, schools, and more.
Would rapid-testing work better than scanning for fever at airports? Than cordon sanitaire? Than panicked efforts to develop, test, and distribute a vaccine that may take a year? Than public-service messaging that urges staying home? Than face masks and handwashing, if that is really the best we can offer a terrified public?
There would certainly be advantages: if PCR rapid testing is sufficiently sensitive—and this is an important if, because we as yet don’t know whether people may be infected without testing positive—still-uninfected people wouldn’t be quarantined with infected ones, on cruise ships or anywhere else, where the risk of exposure increases dramatically. Because it isn’t symptom-dependent but detects the presence of the virus, it has the potential to detect pre-symptomatic infection as well as diagnose current illness. It would also catch people trying to evade travel restrictions with fever-reducing medicines to hide their symptoms.
PCR rapid tests under development today aren’t very expensive, either. Designed especially for low-resource settings, some units are now priced around $10,000. But, as of 2009, the x-ray baggage scanners installed in airports cost $200,000 apiece; the newer models using computed tomography on baggage cost $350,000 each. The millimeter-wave personal scanner you walk through costs $170,000. True, replenishment of equipment would incur the cost of the reagents, but that need not be prohibitive.
Nor does PCR rapid testing invade genetic privacy. PCR scans for pathogens without testing the DNA of the human person; it works by looking for gene regions that match a small snippet of known DNA or RNA from the pathogen of interest. It doesn’t profile people but simply shows whether a bad bug may have invaded someone. We already submit to scanning of our bodies and swabbing of our luggage to keep us from bringing weapons or explosives on board; testing for a dangerous virus would simply keep us from bringing along another kind of threat to others.
To be sure, there are concerns. We’d want to keep careful track of those swabs, perhaps destroying them after a month the way TSA does with its scans. We’d want to use a simple, cheap assay with high sensitivity in order to try to catch as many cases as possible. That would inevitably mean false positive results, especially in a low-incidence population, but people who initially test positive should be retested with more sophisticated methods. There’d be false negatives, too; it’s as yet unknown how early in the process of infection someone might have sufficient viral load to appear in secretions. Increasing our knowledge about the sensitivity and specificity of PCR and other tests used in screening is thus especially imperative. Nevertheless, we’d be confining far fewer people, incubating fewer infections in mandated quarantines, avoiding global travel restrictions, and imposing far less personal and economic disruption than we are today. These measures may have slowed spread somewhat but have not prevented it. We need to find a better, more effective, more patient-respecting way.
Although widespread rapid testing would never fully replace the need for urgent development of vaccines and traditional control measures like face masks, handwashing, avoiding crowds, quarantine, and isolation, and would certainly need to be paired with effective treatment for those who test positive, the spread of transmissible infectious disease could be significantly limited. It may be too late to control COVID-19 completely, but it is not too late—and certainly not too early—to think about additional ways to confront the next outbreak.
Developing the technology and fostering the political will for routine rapid testing not just at airports but in many other places of travel and public contact would allow us to adapt quickly to the future emergence of new/novel infectious diseases as soon as we identify their DNA or RNA and adjust our PCR analyzers to recognize their distinctive genetic signatures. In the current outbreak, the fact that rapid test kits became available less than two months after identifying the virus is remarkable, but what we need to think about more carefully in advance is how to deploy our testing capacities in the most effective way—a way that constitutes the least threat to the individual and provides the greatest protection against spread. The novel 2019 coronavirus originating in Wuhan is neither the last nor the worst pandemic we can expect.
And, as we argued ten years ago in The Patient as Victim and Vector: Ethics and Infectious Disease (PVV), we’re all in this together when it comes to transmissible infectious disease.