Studies on infectiousness and virus culture from COVID-19 samples with CT/ CN correlation have shown that patients with high CT/CN at the end of their disease course might not be as infectious. 9-14,25 Because 1 patient had a presumptive positive result after the negative result, this study shows that this positive-negative-positive pattern could include presumptive positive results. Also, in the setting of a recent positive result on the same testing platform, a patient with this pattern is presumed to be positive for COVID-19 RNA because of scant viral material.
Taiwan’s public health response to the outbreak illustrates the ability to mitigate an outbreak throughout a society. 26 These actions could help blunt an outbreak within a civilian nursing home population. 5 Mitigation within a veteran CLC population has been documented, but the study, which focused on mitigation, did not consider CT/CN values, demographic distribution, testing access of the studied population, or laboratory findings related to disease pathophysiology. 15 A key ingredient in widescale, serial testing is the availability of a rapid turnaround from testing in-house that allowed identification within 24 hours instead of several days at a reference laboratory. 15 Rapid widescale testing would allow clinical teams to optimize the Triangle of Benefit of Widescale Timely Tests for CLC (Figure 3). 15 Timely laboratory testing remains pivotal for CLC veteran residents to aid successful clinical triage and management. Reporting serial CT/CN values can provide additional information to clinicians about the disease course because CT/ CN correlates with viral load, which varies based on where the patient is in the disease course. 9-14 CT/CN values carry significant prognostic value, particularly with respect to intubation and mortality. 8
Limitations
Important limitations to our study include the use of 2 separate RT-PCR platforms. Using different RT-PCR platforms is common in clinical laboratories trying to take advantage of the unique characteristics of different platforms—for example, turnaround time vs high throughput— to manage COVID-19 testing workflow. 25 However, the exact CT/CN values obtained from each platform might not translate to the other, and the general trend (CT/CN values are rising or falling across serial tests) rather than a single value could be useful for clinical correlation. Even when the same platform is used for the serial testing, CT/CN values can be affected by adequacy of specimen collection; therefore, clinical correlation and considering the trend in CT/CN values is necessary for interpretation. 10-14,25 Because of the known trend in viral dynamics, a positive specimen collected with a high CT/CN followed by a subsequent (within 2 days) positive specimen collected with a low CT/CN might be compatible with early detection of COVID- 19 infection in the appropriate clinical context. 10-14 However, detection late in the infection course or even after the symptomatic disease resolved with prolonged viral shedding might show serial positive samples with increasing CT/CN values. 10-14
Patients with prolonged viral shedding might not be infectious.27 Because of the clinical correlation required for interpretation and the other factors that might affect CT/CN values, recommendations advise against using CT/CN values in clinical practice at this time, although these recommendations could change with future research.25 Serial CT/CN values have the potential, if appropriately correlated with the clinical picture, to provide useful information, such as whether the viral load of the sample is relatively high or low and increasing or decreasing.