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Test ID CORBS Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) IgG, Blood Spot

Advisory Information

Molecular testing is recommended for diagnosis of coronavirus disease 2019 (COVID-19) in symptomatic patients. For more information see COVOO / Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) RNA Detection, Varies.


If SARS-CoV-2 vaccine-induced antibody testing is necessary, see VCOV2 / Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) IgG Antibody, Serum.


The dried blood spot specimen should be collected under the supervision of a medical professional or health care provider.

Necessary Information

1. Patient’s race and ethnicity are required.

2. If ordering electronically, answers must be provided for the order entry questions.

3. If not ordering electronically, patient race and ethnicity must be provided on the request form.

Specimen Required

Supplies: Card-Blood Spot Collection (Filter Paper) (T493)


Preferred: Blood Spot Collection Card

Acceptable: Whatman Protein Saver 903 Paper, Ahlstrom 226 filter paper and Munktell filter paper

Specimen Volume: 2 Filled blood spots

Collection Instructions:

1. See Dried Blood Spot Collection Tutorial for how to collect blood spots: 

2. Let blood dry completely on filter paper at ambient temperature in a horizontal position for a minum of 3 hours.

3. At least 2 spots should be complete, ie, unpunched.

4. Do not expose specimen to heat, moisture, or direct sunlight.

5. Do not stack wet specimens.

6. Keep specimen dry.

Additional Information:

1. For collection instructions, see Blood Spot Collection Instructions-Fingerstick in Special Instructions.

2. For collection instructions in Portuguese, see Blood Spot Collection Instructions-Fingerstick-Portuguese in Special Instructions.

3. For collection instructions in Spanish, see Blood Spot Collection Instructions-Fingerstick-Spanish in Special Instructions.

Useful For

Screening for the detection of IgG-class antibodies against severe acute respiratory syndrome coronavirus 2 (SARS- CoV-2) using dried blood spot specimens


This test should not be used to detect recent or acute coronavirus disease 2019 (COVID-19) or for documentation of SARS-CoV-2 vaccine response.

Method Name

Microsphere Multiplex Flow Immunoassay (MFI)

Reporting Name

SARS-CoV-2 IgG, Bld Spot

Specimen Type

Whole blood

Specimen Minimum Volume

1 Blood spot

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Ambient 25 days FILTER PAPER

Clinical Information

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 2 to 14 days. Typically, immunocompetent individuals with COVID-19 develop detectable SARS-CoV-2 IgG-class antibodies 8 to 14 days following onset of symptoms. Patients tested prior to this time may be negative for SARS-CoV-2 IgG antibodies.

Reference Values


Reference values apply to all ages.



No IgG antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detected. Negative results may occur if the test is done too soon following infection, in patients who are immunosuppressed, or in patients with very mild or asymptomatic infection. This test does not rule out active or recent coronavirus disease 2019 (COVID-19) and will not detect SARS-CoV-2 vaccine-induced antibodies.



Results suggest infection with SARS-CoV-2 at some time in the past. A positive result does not indicate protection against reinfection with SARS-CoV-2. False-positive results may occur. Confirmatory testing using a venipuncture blood draw may be considered in low-risk individuals or those residing in low-prevalence regions.



Presence or absence of antibodies to SARS-CoV-2 could not be determined. Repeat testing on a new dried blood spot specimen or a venipuncture blood draw may be considered.

Clinical Reference

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. Nat Med. 2020;26(7):1033-1036. doi: 10.1038/s41591-020-0913-5

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. Microbes Infect. 2020;22(4-5):206-211. doi: 10.1016/j.micinf.2020.05.008

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

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
CORBS SARS-CoV-2 IgG, Bld Spot 94761-4


Result ID Test Result Name Result LOINC Value
CRBSR SARS-CoV-2 IgG, Ab 94761-4
SRACE Patient's Race 72826-1
SETHN Patient's Ethnicity 69490-1