Test Catalog

Test ID: VCOV2    
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) IgG Antibody, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Detection of IgG-class antibodies against severe acute respiratory syndrome coronavirus 2, agent of coronavirus disease 2019 (COVID-19)

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a positive-sense, single-stranded RNA virus that causes coronavirus disease 2019 (COVID-19). Like other coronaviruses that infect humans, SARS-CoV-2 can cause both upper and lower respiratory tract infection. Symptoms can range from mild (ie, the common cold) to severe (ie, pneumonia) in both healthy and immunocompromised patients. SARS-CoV-2 transmission occurs primarily via respiratory droplets. During the early stages of COVID-19, symptoms maybe nonspecific and resemble other common respiratory tract infections, such as influenza.


The incubation period for COVID-19 ranges from 5 to 7 days. Typically, immunocompetent individuals with COVID-19 develop detectable IgG-class antibodies against SARS-CoV-2 approximately 8 to 11 days following onset of symptoms. Patients tested prior to this time may be negative for SARS-CoV-2 IgG antibodies.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


Interpretation Provides information to assist in interpretation of the test results

Negative: No IgG antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detected. Negative results may occur in serum collected too soon following infection, in immunosuppressed patients, or in some individuals with prior mild illness. Follow-up testing with a molecular test is recommended in symptomatic patients. This test should not be used to exclude active/recent coronavirus disease 2019 (COVID-19).


Positive: SARS-CoV-2 IgG antibodies detected. Results suggest recent or prior infection with SARS-CoV-2. Correlation with epidemiologic risk factors and other clinical and laboratory findings is recommended. Serologic results should not be used to diagnose recent SARS-CoV-2 infection. Protective immunity cannot be inferred based on these results alone. Infrequently, false-positive results may be due to prior infection with other human coronaviruses.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The sensitivity of VITROS Anti-SARS-CoV-2 IgG test in early infection is unknown. Negative results do not preclude severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. If an acute infection is suspected, direct testing for SARS-CoV-2 is necessary.


False-positive results for VITROS Anti-SARS-CoV-2 IgG test may occur due to cross-reactivity from pre-existing antibodies or other possible causes.


Performance characteristics have not been established for the following specimen characteristics:

-Grossly icteric (total bilirubin level of >40 mg/dL)

-Grossly lipemic (triolein level of >2000 mg/dL)

-Grossly hemolyzed (hemoglobin level of >1000 mg/dL)

-Those containing biotin (biotin level of >3510 ng/mL)

-Containing particulate matter

-Cadaveric specimens

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Okba N, Muller MA, Li W, et al: Severe acute respiratory syndrome coronavirus 2-specific antibody responses in coronavirus disease 2019 patients. Emerg Infect Dis. 2020 Apr 8;26(7). doi: 10.3201/eid2607.200841

2. Amanat F, Stadlbauer D, Strohmeier S, et al: A serologic assay to detect SARS-CoV-2 seroconversion in humans. medRxiv 2020.03.17.20037713. doi: 10.1101/2020.03.17.20037713. Available at www.medrxiv.org/content/10.1101/2020.03.17.20037713v2

3. Liu L, Liu W, Wang S, Zheng S: A preliminary study on serological assay for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 238 admitted hospital patients. medRxiv 2020.03.06.20031856. doi: 10.1101/2020.03.06.20031856 Available at www.medrxiv.org/content/10.1101/2020.03.06.20031856v1

4. Zhang W, Du RH, Li B, et al: Molecular and serologic investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Emerg Microbes Infect. 2020 Feb 17;9(1):386-389.  doi: 10.1080/22221751.2020.1729071