As we prepare to reopen tourism and restart our economy, robust testing as well as contact tracing and tracking the spread of COVID-19 are imperative to protecting locals and visitors alike.
The gold standard for COVID-19 testing, nucleic acid amplification tests (NAATs), have a high degree of accuracy but are costly, require specialized equipment, reagents, trained personnel and have long turnaround times. NAATs detect viral genetic material through reverse-transcription polymerase chain reaction (rt-PCR), a procedure which recognizes viral RNA, converts it to DNA and then amplifies it for detection by fluorescence.
Samples are collected with nasal swabs, oral swabs or saliva capture. Deep nasal swabbing (Nasopharyngeal) is considered the optimal collection method because of the presence and concentration of SARS-CoV-2 viral particles in the upper respiratory tract. Deep nasal swabbing must be administered by trained clinicians as it is a more invasive procedure requiring specialized technique to avoid pain, discomfort and complications to subjects.
Shallow nasal swabs, oral swabs and saliva collections are simpler, less invasive methods and can be self-administered. These collections methods are, however, less accurate than deep swabbing and require users to correctly carry out procedures.
In contrast to NAATs, rapid antigen tests detect the presence of viral proteins collected by nasal swabbing. Rapid antigen tests while less accurate, are simple, quick, affordable and scalable. There are various platforms for use in medical, institutional, and community settings. Automated or simplified systems, similar to at-home pregnancy tests, can provide point-of-care diagnostics in minutes for as little as $5.
Dental offices, for example, are considering implementation of these rapid tests to screen patients prior to treatment. Colleges, professional sports teams, and other groups are using this form of testing. Rapid antigen test platforms are more easily mass produced than NAATs, making them attractive for wide-scale testing efforts.
While antibody (serology) testing offers little value in identifying active infections, it can tell us who has had the virus. These tests detect virus specific antibodies circulating in blood. When the immune system encounters the SARS-CoV-2 virus, it mounts a series of responses that includes the production of antibodies. Typically, an antibody response is not reliably detectable until 14 days post-infection and will remain detectable for several months after clearing the virus. A small fraction of infected individuals will not mount an antibody response. The detection of virus specific antibodies is indicative of an exposure at some point in the recent past as opposed to confirming an active infection.
It has not yet been fully established that virus-specific antibodies confer immunity. Moreover, the use of antibodies in treatment is also not fully understood. An experimental synthetic monoclonal antibody cocktail was administered to the president. The efficacy of this treatment remains unclear as it is still being studied in clinical trials and is not widely available.
The Hawaii pre-travel testing program is a step in the right direction. There is room for improvement. Multiple tests are needed because it takes nearly a week for the viral load to build up to the point of detectability. Tests administered during the initial days post infection will likely return inaccurate results.
Ideally, all travelers would be tested with two NAATs administered before and after arrival in Hawaii. Limitations in testing capacity and cost considerations make this approach difficult to successfully implement. Using a combination of both NAAT and rapid antigen testing may provide additional layers of security, convenience, and affordability. A pooled approach where samples from same-household travelers are combined into a single NAAT would further reduce financial burdens and increase efficiencies of testing.
Understanding and implementation of testing, linked to contact tracing, quarantine and isolation is essential to informed, science- based policy-making in our collective efforts to prevent community spread of COVID-19 throughout our island home.
Kenneth T. Kim holds a master’s degree from Johns Hopkins University and is an infectious disease biologist in the D.C. area. His dad, Karl Kim, Ph.D., is a professor of urban and regional planning at the University of Hawaii-Manoa.