J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Case Report

Volume 12, Number 5, May 2020, pages 315-319

A Comprehensive Approach Is Vital for Diagnosing COVID-19: A Case of False Negative

Figure 1. Different planes of the CT scan showing bilateral worsening of ground-glass opacities at bases. CT: computed tomography.

**Table 1.** Summary of Laboratory Abnormalities
Laboratory findings	Patients value (normal values)
CRP: C-reactive protein; LDH: lactate dehydrogenase; INR: international normalized ratio; BMI: body mass index.
White blood cell count	8.0 (4.8 - 10.8 × 10⁹/L)
Absolute lymphocyte count	1.5 (1.0 - 3.5 × 10⁹/L)
Procalcitonin	< 0.05 (< 0.05)
D-dimer	186 (< 255 ng/mL)
CRP (high)	13.2 (0.000 - 0.744 mg/dL)
LDH (high)	390 (100 - 235 U/L)
Serum ferritin	284 (11 - 307 ng/mL)
Erythrocyte sedimentation rate (high)	59 (0 - 20 mm/h)
Respiratory viral panel	Negative
Vitamin D (low)	17 (> 30)
INR (high)	1.3 (0.9 - 1.2)
BMI	42.91 kg/m²

Table 1. Summary of Laboratory Abnormalities

Laboratory findings

Patients value (normal values)

CRP: C-reactive protein; LDH: lactate dehydrogenase; INR: international normalized ratio; BMI: body mass index.

White blood cell count

8.0 (4.8 - 10.8 × 10⁹/L)

Absolute lymphocyte count

1.5 (1.0 - 3.5 × 10⁹/L)

Procalcitonin

< 0.05 (< 0.05)

D-dimer

186 (< 255 ng/mL)

CRP (high)

13.2 (0.000 - 0.744 mg/dL)

LDH (high)

390 (100 - 235 U/L)

Serum ferritin

284 (11 - 307 ng/mL)

Erythrocyte sedimentation rate (high)

59 (0 - 20 mm/h)

Respiratory viral panel

Negative

Vitamin D (low)

17 (> 30)

INR (high)

1.3 (0.9 - 1.2)

BMI

42.91 kg/m²

**Table 2.** Different Methods of Testing
Methods of testing	What the test interprets	Turnaround time
ELISA: enzyme-linked immunosorbent assay; RDT: rapid diagnostic test.
Neutralization assay	Tests to look for active antibodies in subject serum which can inhibit virus growth ex vivo. Indicates if the patient is protected against future infection.	3 - 5 days
ELISA	Quantify the presence or absence of antibodies against the virus in the subject’s serum.	1 - 5 h
RDT	Qualitatively tests for the presence or absence of antibodies against virus in the subject’s serum. Cannot quantify the antibody titer.	10 - 30 min

Table 2. Different Methods of Testing

Methods of testing

What the test interprets

Turnaround time

ELISA: enzyme-linked immunosorbent assay; RDT: rapid diagnostic test.

Neutralization assay

Tests to look for active antibodies in subject serum which can inhibit virus growth ex vivo. Indicates if the patient is protected against future infection.

3 - 5 days

ELISA

Quantify the presence or absence of antibodies against the virus in the subject’s serum.

1 - 5 h

RDT

Qualitatively tests for the presence or absence of antibodies against virus in the subject’s serum. Cannot quantify the antibody titer.

10 - 30 min

**Table 3.** Diagnostic Tests Approved for COVID-19 in the USA as per FDA
Company/method of testing	Country of development	Sensitivity and specificity of the test
ELISA: enzyme-linked immunosorbent assay; COVID-19: coronavirus disease 2019; FDA: Food and Drug Administration; IgG: immunoglobulin G; RDT: rapid diagnostic test.
Mount Sinai laboratory COVID-19 ELISA IgG antibody test/ELISA	USA	Not available
VITROS Immunodiagnostic Products Anti-SARS-CoV-2 Total Reagent Pack/Total Calibrator (Ortho Clinical Diagnostics)/Modified ELISA	USA	Sensitivity: 83%, specificity: 100%
Cellex/RDT	USA/China	Sensitivity: 93.8%, specificity: 95.6%
ChemBio/RDT	USA	Not available
Epitope Diagnostics, Ltd/ELISA	USA	Not available
BioMedomics/RDT for research use only	USA	Sensitivity: 88.66%, specificity: 90.63%
Ray Biotech/RDT for research use only	USA	Not available
Emory University/ELISA for research use only	USA	Not available

Table 3. Diagnostic Tests Approved for COVID-19 in the USA as per FDA

Company/method of testing

Country of development

Sensitivity and specificity of the test

ELISA: enzyme-linked immunosorbent assay; COVID-19: coronavirus disease 2019; FDA: Food and Drug Administration; IgG: immunoglobulin G; RDT: rapid diagnostic test.

Mount Sinai laboratory COVID-19 ELISA IgG antibody test/ELISA

USA

Not available

VITROS Immunodiagnostic Products Anti-SARS-CoV-2 Total Reagent Pack/Total Calibrator (Ortho Clinical Diagnostics)/Modified ELISA

USA

Sensitivity: 83%, specificity: 100%

Cellex/RDT

USA/China

Sensitivity: 93.8%, specificity: 95.6%

ChemBio/RDT

USA

Not available

Epitope Diagnostics, Ltd/ELISA

USA

Not available

BioMedomics/RDT for research use only

USA

Sensitivity: 88.66%, specificity: 90.63%

Ray Biotech/RDT for research use only

USA

Not available

Emory University/ELISA for research use only

USA

Not available