Table 2.
Studies on SARS CoV-2 Serology Research Assays
| Date/author/study type | Method, sample type/number | Time from onset to test | Statistical parameters | Limitations |
|---|---|---|---|---|
| 02/17/20 Zhang et al. Case series45 | ELISA kits developed using SARSr-CoV Rp3 NP as the antigen. | Day 10 of treatment | 1st day of sampling: IgM and IgG titers were relatively low or undetectable 5th day of sampling: increase in both IgM and IgG seen in nearly all patients |
No data after day 5. No data listed for specificity of ELISA kits. |
| 02/27/20 Li et al. Diagnostic Accuracy Cross-sectional study38 | LFIA - IgM and IgG antibodies to recombinant antigen that is the receptor binding domain of SARS-CoV-2 Spike Protein. | Day 8 to day 33 after onset |
Sensitivity: IgG + IgM: 88.66%; IgG: 70.53%; IgM: 82.62% Specificity: IgG + IgM: 116/128 (90.63%); IgG: 126/128 (91.41%); IgM: 117/128 (91.41%) |
This test cannot confirm virus presence or provide quantitative information. Day of sample collection was inconsistent from patient to patient |
| 03/19/20 Haveri et al. Case series43 | Serum on days 4, 9, 10, and 20 from onset of symptoms. IgM and IgG antibodies against SARS-CoV-2 were analyzed using IFA | Day 3 to day 23 after onset | Day 4: antibodies were undetectable. Day 9: IgG titer: 80; IgM titer: 80. Day 20: IgG: 1,280; IgM titer: 320 | This study was able to track IgM and IgG temporally up to day 23 d.p.o. Sample collection was inconsistent from patient to patient. No specificity data noted. |
| 03/21/20 Guo et al. Diagnostic Accuracy Comparative Study42 | 208 samples from 140 cases cases. Indirect ELISA for IgM, IgA, and IgG. 135 samples from adults with respiratory tract infections & 150 healthy adults were controls | 1–7 days post-symptom onset (41 samples), 8–14 days (84 samples), 14+ days (83 samples) |
IgM: Sensitivity: 90.4%; Specificity: 100% IgG: Sensitivity: 77.9%; Specificity: 100% IgA: Sensitivity: 93.3%; Specificity: 100% |
Cross-sectional sample of specimens was used to determine the kinetics of antibodies; however, each patient has different kinetics for the development of antibodies. |
| 03/28/20 Zhao et al. Diagnostic Accuracy Comparative Study40 | 173 patients, serial samples to a total of 535 samples. ELISA IgM, and IgG. for receptor binding domain of the Spike protein, | 1–39 days after onset. Groups : 1–7 days (94 patients), 8–14 (135 patients), 15–39 (90 patients) |
Ab: Sensitivity:93.1% Specificity: 99.1% IgM: Sensitivity: 82.7%; Specificity: 98.6% IgG: Sensitivity: 64.7%; Specificity: 99% |
Sensitivities varied depending on which day after onset samples were collected. Patients were selected based on positive RT-PCR, potentially missing atypical patients with lower respiratory viral load |
| 03/30/20 Cassaniti et al. Diagnostic Accuracy Cross-sectional study41 | 110 subjects, VivaDiag COVID-19 IgM/IgG Rapid LFIA. | Positive control collected at median 7 days (IQR 4–11). |
COVID-19:
Sensitivity of combined IgM and IgG: 63.3% were positive; 16.7% were weakly positive; 16.7% were negative, 1/30 was positive for IgM, negative for IgG 50 patients evaluated in ED Sensitivity: 18.4%; Specificity: 91.7%. |
Advantage of study is that patients enrolled from the ED provided a relatively consistent time frame of symptom onset. Limitation of the study is that there is no temporal data to follow. |
| 03/30/20 Liu et al. Diagnostic Accuracy Case-Control study44 | 214 patients, 100 healthy controls. The recombinant nucleocapsid (rN) protein-based ELISA IgM or IgG. | Samples divided into 1–5 (22), 6–10 (38), 11–15 (54), 16–20 (55), 21–30 (32), 31–35 (6), and >35 (7) days post disease onset |
rN-based ELISA Sensitivity: 80.4%; Specificity: 100% rS-based ELISA Sensitivity:82.2%; Specificity: 100% |
Temporal data available, showing that IgM and/or IgG of SARS-CoV-2 might be positive at 11–15 d.p.o. Decreased positive rate of IgM was observed at > 35 d.p.o. A limitation is that samples were not collected from these patients after discharge. |
Abbreviations: ELISA – enzyme-linked immunosorbent assay, IFA – immunofluorescence assay, d.p.o – days post-disease onset, LFIA – lateral flow immunoassay, IgM-Immunoglobulin M, IgG-immunoglobulin G, IgA-immunoglobulin A, RT-PCR – reverse Transcriptase polymerase chain reaction, SARS-CoV-2 -severe acute respiratory syndrome coronavirus-2.