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SARS-CoV-2 Immunoglobulin M (IgM) Antibody in Serum/Plasma

Published: August 9, 2026Updated: August 16, 2026

This test detects antibodies called IgM that your body produces in response to exposure to the SARS-CoV-2 virus, which causes COVID-19. IgM antibodies typically appear shortly after infection but may decline over time.

Quick summary

["IgM antibodies help identify recent COVID-19 infection, often within days of symptoms starting."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
94564-2
Short code
SARS-CoV-2 IgM SerPl Ql IA
Synonyms
SARS-CoV-2 IgM SerPl Ql IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Does This Test Measure?

The test measures the presence of IgM antibodies specific to the SARS-CoV-2 virus in your blood. These antibodies are part of your immune system’s response to infection. IgM is usually the first type of antibody your body makes after exposure to a virus like COVID-19.

When Might This Test Be Used?

Healthcare providers may use this test to help determine if you’ve recently been infected with COVID-19, especially if you have symptoms or were exposed to someone with the virus. It can also be used in research or certain diagnostic contexts where IgM detection is relevant.

How Is the Sample Collected?

A small amount of blood is drawn from a vein in your arm. The blood is then separated into serum or plasma for testing.

What Are the Limitations?

IgM antibodies can sometimes be present in people who haven’t been infected with COVID-19, especially those who have been vaccinated or exposed to other viruses. False positives or negatives can occur, so results should always be interpreted by a healthcare provider in the context of your medical history and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgM antibodies are useful for identifying recent infection because they appear quickly after exposure but tend to decrease over time. While IgG antibodies (detected in other tests) provide a longer-lasting immune response, IgM is often the first marker to signal a recent viral encounter. This test can support diagnosis in acute or early-stage COVID-19 cases but should not replace other diagnostic methods like PCR testing when available.

Short name

IgM Antibody to SARS-CoV-2

Frequently asked questions

Why might my IgM test result be positive even if I don’t have COVID-19 symptoms?
IgM antibodies can sometimes be detected in people who haven’t had COVID-19, such as those who have been vaccinated or exposed to other respiratory viruses. Additionally, IgM levels can fluctuate naturally, so a positive result should be reviewed by your healthcare provider to understand the context.
Can IgM antibodies stay in my system long after I’ve recovered from COVID-19?
IgM antibodies typically decline over weeks to months after infection. However, their presence doesn’t always indicate an active infection, so follow-up testing or clinical evaluation may be needed to determine if symptoms or exposure warrant further action.
Is this test the same as a PCR test for COVID-19?
No, this test looks for antibodies (IgM) produced by your immune system in response to the virus, while a PCR test directly detects the virus itself in your respiratory samples. Both tests serve different purposes in diagnosing COVID-19, and results should be considered together with clinical judgment.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy