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Difficulties With COVID-19 Prescreening For Hawai‘i

4:05 AM · May 23, 2020

Recent news that the federal government allows the testing of travelers prior to arrival in Hawai‘i to avoid the State’s 14 day quarantine has raised hopes for the return of tourism to the islands. A rough outline for a prescreening system has been proposed by the State Legislature which could allow for increased travel with reduced restrictions to the islands, and is not against the rules of the Federal Aviation Administration (FAA) and the US Department of Transportation (USDOT). What would this system potentially look like? How do we reactivate tourism without driving up coronavirus infection rates? It’s hard to say. Add in the complexities of testing asymptomatic and presymptomatic cases of COVID-19, and any proposed testing regime for screening travelers is not likely to be easy to implement and manage. Prior to COVID-19, Hawai‘i was seeing roughly 33,000 passenger arrivals a day. In order to return to even 75% of pre-pandemic arrival numbers, while also protecting our local health care capacity, a protocol is needed with out-of-state health care providers to process test samples and report their results to the State of Hawai‘i. In turn, the State would need the capacity to handle over 24,000 test results every 24 hours. This is further complicated by the need to standardize & report results from other regions in real time to be able to properly screen people upon arrival in Hawai‘i. Any system will take time to develop and implement. The logistics alone will be no small challenge, and that will only be complicated by the rate of false-negative tests on those without symptoms: “Over the 4 days of infection before the typical time of symptom onset (day 5), the probability of a false-negative result in an infected person decreases from 100% (95% CI, 100% to 100%) on day 1 to 67% (CI, 27% to 94%) on day 4.” (Kurcirka, et al) Prior to symptom onset, the reliability of antigen testing to accurately detect infection is dubious at best. Bruce Anderson from the Hawai‘i Department of Health has repeatedly mentioned limitations on use of antigen PCR tests on those that do not have symptoms. The frequency of false-negative results in the first 4 days of infection is staggering. The primary concerns with a potential prescreening system in my eyes are: - The timetable for COVID-19 to present symptoms - The contagious nature of COVID-19 prior to symptom onset - The unreliability of antigen PCR testing before symptom onset - The chance of infection after the test is administered Care must be taken in the creation of a precheck system using RT-PCR tests looking for COVID-19 as a basis for removing the 14 day quarantine. What has been pitched so far? Rep. Bob McDermott has proposed a system for a prescreen process. However, this proposal does not address the concerns listed above. While the prescreening mock-up isn’t as sound to deploy as suggested, it does provide a preliminary outline of how Hawai‘i can properly screen arriving passengers without requiring a mandatory 14 day quarantine. Another option included by Rep McDermott are Abbott ID NOW rapid isothermal PCR machines. However, recent studies have called into question the accuracy of the tests in the field due to difficulties in sample collection. Abbot Labs disputes these results. “Regardless of method of collection and sample type, Abbot ID NOW COVID-19 missed a third of the samples detected positive by Cepheid Xpert Xpress when using NP swabs in VTM and over 48% when using dry nasal swabs.” (Basu, et al) Because of these large percentage errors, even a layered detection system will have significant gaps. Advancements are needed both in the science of the virus and in the accuracy of detection, especially presymptomatic testing, for this approach to succeed. It remains a possible way forward, if these issues can be solved and we have robust contact tracing and quick isolation of clusters seeded by COVID-19 carriers who slip through the gaps. Once such a system can be implemented, the big question will be how many tourists can we expect to return during a global pandemic? Even if Hawai‘i is able to manage any and all clusters of COVID-19 that result from reactivated travel, the prospects for tourism’s triumphant return present more questions than answers. As long as the pandemic persists, I expect below-average tourism, no matter how hard we pitch abroad Hawai‘i as a ‘safe place’. Hawai‘i has been keeping the curve flat. While we explore options to reopen our tourism driven economy, island unemployment is at historic highs following the mid-March ‘stay-at-home’ order, and the urge to reopen is strong. We must view living with COVID-19 as a marathon and not a sprint. The recovery will have hurdles and we must be willing to adapt and persist to keep all of Hawai‘i a safe place to live and visit. Edited and reviewed by Philip Ong, Dave Smith, and Maren Purvis. References: Kurcirka, et al., "Variation in False-Negative Rate of Reverse Transcriptase Polymerase Chain Reaction–Based SARS-CoV-2 Tests by Time Since Exposure" Basu, et al., "Performance of the rapid Nucleic Acid Amplification by Abbott ID NOW COVID-19 in nasopharyngeal swabs transported in viral media and dry nasal swabs, in a New York City academic institution" Full Pre-Departure Testing Source from Rep. Bob McDermott and Gene Ward, Making Hawai‘i Safe For Travel.


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