CT values
Clinical SARS-CoV-2 testing was completed on five different platforms
depending on patient encounter classification and turn-around-time
requirements. Therefore, to standardize results and enable further
characterization of SARS-CoV-2 CT values, we identified
a subgroup of 7 children who had multiple respiratory samples available
for repeat testing. Demographic and clinical information regarding this
subgroup is summarized in Table 3.
Using the CDC assay for repeat testing, we evaluated SARS-CoV-2
CT values for a total of 20 specimens from these 7
individuals over time, presuming CT value as a surrogate
for viral load. Five of 7 (71%) children had initial CTvalues <30, indicating a moderate to high viral load, and of
these, 4 (57%) children had repeat testing 21 to 30 days later with
CT values <30, suggesting persistence of
moderate to high viral loads (Figure 3). Two of 7 (29%) patients had a
single negative test followed by a positive test. By 40 days after
initial positive testing, 6 of 7 (86%) children had negative tests
(indicated as CT of 40) or CT values
>35. The exception was one patient who remained positive
until day 85. One patient (Patient 4) had a positive result on a
specimen when tested clinically but a negative result when re-tested on
the CDC assay. This is most likely indicative of a low viral load in the
specimen, since the assay used for clinical testing and the CDC assay
have similar, but not identical, limits of detection.