Product Manual

5 (6)
Seroconversion study: Days post-PCR testing
Days between date of
PCR comparator test and
collection of
plasma/serum sample
Number
of
Samples
Tested
IgM
Positive
results
IgM
PPA
IgG
Positive
results
IgG PPA
0-7 days 26 1 3.85% 1 3.85%
8-14 days 29 25 86.21% 18 62.07%
≥15 days 26 24 92.31% 23 88.46%
Seroconversion study: Days post-symptom onset
Days post onset of symptoms
Number of
Samples
Tested
Combined
Positive
results
PPA
0-7 days 26 1 3.85%
8-14 days 29 26 89.66%
≥15 days 26 25 96.15%
The specificity of the Clarity COVIBLOCK
TM
COVID-19 IgG/IgM Rapid
Test Cassette was evaluated using a total of 220 plasma/ serum
samples collected from individuals, before the COVID-19 outbreak.
In the first study, 80 presumed negative plasma samples (K
2
EDTA)
collected within the US, before October 2019 were tested; 30
presumed negative plasma samples (K
2
EDTA) collected within Cote
d-Ivoire, in 2016 were tested; 58 presumed negative plasma samples
(K
2
EDTA) collected within Uganda, in 1995 were tested. Testing were
performed at the Washington University School of Medicine.
In the second study, 52 presumed negative serum sample collected
within France, between October and November 2019, were tested.
Origin
Sample
Type
Number
of
Samples
Tested
Combined
IgG & IgM
Negative
results
NPA 95% CI
United States
Plasma
80
79
98.8%
93.25%-99.78%
Cote d-Ivoire
Plasma
30
29
96.7%
83.33%-99.41%
Uganda*
Plasma
58
52
89.7%
79.22%-95.17%
France
Serum
52
51
98.1%
89.88%-99.66%
*The low NPA performance observed was obtained from samples that
were collected in 1995. False positives most likely were attributed to
prolonged storage of these samples. NPA was acceptable in all other
negative agreement studies.
The Clarity COVIBLOCK
TM
COVID-19 IgG/IgM Rapid Test Cassette
was tested on 06/17/2020 at the Frederick National Laboratory for
Cancer Research (FNLCR) sponsored by the National Cancer Institute
(NCI). The test was validated against a panel of previously frozen
samples consisting of 30 SARS-CoV-2 antibody-positive serum
samples and 80 antibody-negative serum and plasma samples. Each
of the 30 antibody-positive samples were confirmed with a nucleic acid
amplification test (NAAT) and both IgM and IgG antibodies were
confirmed to be present in all 30 samples. The presence of antibodies
in the samples was confirmed by several orthogonal methods prior to
testing with the Clarity COVIBLOCK
TM
COVID-19 IgG/IgM Rapid Test
Cassette Antibody Test. The presence of IgM and IgG antibodies
specifically was confirmed by one or more comparator methods.
Antibody-positive samples were selected at different antibody titers. All
antibody-negative samples were collected prior to 2020 and include i)
Seventy (70) samples selected without regard to clinical status,
“Negatives” and ii) Ten (10) samples selected from banked serum from
HIV+ patients, “HIV+”. Testing was performed by one operator using
one lot of Clarity COVIBLOCK
TM
COVID-19 IgG/IgM Rapid Test
Cassette antibody tests. Confidence intervals for sensitivity and
specificity were calculated per a score method described in CLSI
EP12-A2 (2008). For the evaluation of cross-reactivity with HIV+, it
was determined whether an increased false positive rate among
antibody-negative samples with HIV was statistically higher than the
false positive rate among antibody-negative samples without HIV (for
this, a confidence interval for the difference in false positive rates was
calculated per a score method described by Altman). The results and
data analysis are shown in the tables below.
Important limitations of the study:
1. Samples were not randomly selected, and sensitivity and
specificity estimates may not be indicative of the real-world
performance of the device
2. These results are based on serum and plasma samples only
and may not be indicative of performance with other sample
types, such as whole blood, including finger stick blood.
3. Information about anticoagulants used is not known.
4. The number of samples in the panel is a minimally viable
sample size that still provides reasonable estimates and
confidence intervals for test performance, and the samples
used may not be representative of the antibody profile
observed in patient populations.
The Clarity COVIBLOCK
TM
COVID-19 IgG/IgM Rapid Test Cassette
(Whole Blood/ Plasma/ Serum) has been tested for anti-influenza A
virus, anti-influenza B virus, anti-RSV, anti-Adenovirus, HBsAg, anti-
Syphilis, anti-H. Pylori, anti-HIV, anti-HCV, ANA and HAMA positive
specimens. The results showed no cross-reactivity. Some cross
reactivity was observed with samples positive for Rheumatoid Factor.
It is possible to cross-react with samples positive for MERS-CoV
antibody. Positive results may be due to past or present infection with
non-SARS-CoV-2 coronavirus strains, such as coronavirus HKU1,
NL63, OC43, or 229E.
The following potentially interfering substances were added to
COVID-19 negative specimens.
Acetaminophen:
20 mg/dL
Caffeine:
20 mg/dL
Albumin:
2 g/dL
Acetylsalicylic Acid:
20 mg/dL
Gentisic Acid
20 mg/dL
Ethanol:
1%
Ascorbic Acid:
2 g/dL
Creatine:
200 mg/dL
Bilirubin:
1 g/dL
Hemoglobin:
1000 mg/dL
Oxalic Acid:
60 mg/dL
Uric acid:
20 mg/mL
None of the substances at the concentration tested interfered in the
assay.
BIBLIOGRAPHY
1. Weiss SR, Leibowitz JL. Coronavirus pathogenesis. Adv Virus
Res 2011;81:85-164.
NEGATIVE AGREEMENT
NCI EVALUATION
CROSS-REACTIVITY
INTERFERERING SUBSTANCES