Role of serological rapid antibody test in the management of possible COVID-19 cases

Abstract

Background: Although the detection of viral particles by reverse transcription polymerase chain reaction (RT-PCR) is the gold standard diagnostic test for coronavirus disease 2019 (COVID-19), the false-negative results constitute a big challenge.

Aim: To examine a group of patients diagnosed and treated as possible COVID-19 pneumonia whose multiple nasopharyngeal swab samples were negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by RT-PCR but then serological immunoglobulin M/immunoglobulin G (IgM/IgG) antibody against SARS-CoV-2 were detected by rapid antibody test.

Methods: Eighty possible COVID-19 patients who had at least two negative consecutive COVID-19 RT-PCR test and were subjected to serological rapid antibody test were evaluated in this study.

Results: The specific serological total IgM/IgG antibody against SARS-CoV-2 was detected in twenty-two patients. The mean age of this patient group was 63.2± 13.1-years-old with a male/female ratio of 11/11. Cough was the most common symptom (90.9%). The most common presenting chest computed tomography findings were bilateral ground glass opacities (77.2%) and alveolar consolidations (50.1%). The mean duration of time from appearance of first symptoms to hospital admission, to hospital admission, to treatment duration and to serological positivity were 8.6 d, 11.2 d, 7.9 d, and 24 d, respectively. Compared with reference laboratory values, serologically positive patients have shown increased levels of acute phase reactants, such as C-reactive protein, ferritin, and procalcitonin and higher inflammatory markers, such as erythrocyte sedimentation rate, lactate dehydrogenase enzyme, and fibrin end-products, such as D-dimer. A left shift on white blood cell differential was observed with increased neutrophil counts and decreased lymphocytes.

Conclusion: Our study demonstrated the feasibility of a COVID-19 diagnosis based on rapid antibody test in the cases of patients whose RT-PCR samples were negative. Detection of antibodies against SARS-CoV-2 with rapid antibody test should be included in the diagnostic algorithm in patients with possible COVID-19 pneumonia.

Keywords: COVID-19; High resolution computed tomography; Pneumonia; Rapid antibody test; Reverse transcription polymerase chain reaction; Serology.

Figure 1

Example of the radiological images of a patient whose multiple reverse transcription polymerase chain reaction were negative but serological immunoglobulin M/immunoglobulin G against severe acute respiratory syndrome coronavirus 2 positive. A: Chest radiograph of coronavirus disease 2019 (COVID-19) patient showing the bilateral infiltrates; B-D: High resolution computed tomography images showing the bilateral reticular and ground-glass opacities of COVID-19 patient.

Figure 2

Example of the radiological images of a patient whose multiple reverse transcription polymerase chain reaction were negative but serological immunoglobulin M/immunoglobulin G against severe acute respiratory syndrome coronavirus 2 positive. A: Chest x-ray of the coronavirus disease 2019 (COVID-19) patient showing the bilateral infiltrates before treatment; B: Chest x-ray of the COVID-19 patient showing reduced bilateral infiltrates after treatment.

Figure 3

High resolution computed tomography images of coronavirus disease 2019 patient showing the bilateral ground-glass opacities and consolidations.

Figure 4

High resolution computed tomography images showing the bilateral patchy ground-glass opacities in a coronavirus disease 2019 patient.

Figure 5

High resolution computed tomography images in a severe coronavirus disease 2019 patient showing the bilateral patchy ground-glass opacities with consolidations.

Figure 6

High resolution computed tomography images of a severe coronavirus disease 2019 patient showing the bilateral fibroreticular infiltrates with crazy-paving pattern.