HSV IgG Blood Test: What It Measures, How to Read Your Results, and What Comes Next

HSV-2 IgG Type Specific Ab: Positive & Low Positive Results

Sample type: Serum

Other names: HSV-2 IgG, Type Specific Ab, HSV 2 IgG Type Spec, Herpes Simplex Virus Type 2 IgG, Type-Specific Antibody, HSV-2 Type-Specific IgG, HSV-2 Glycoprotein G Antibody, IgG, HSV-2 gG2 Antibody, HerpeSelect HSV-2 IgG, Roche Elecsys HSV-2 IgG, DiaSorin LIAISON HSV-2 IgG, HSV-2 IgG Screening Index, HSV-2 ELISA IgG

Optimal result: 0 – 0.91 index

Written May 13, 2026

Updated August 31, 2026

By Healthmatters Editorial Team

Peer-reviewed sources

A high HSV-2 IgG result — meaning your index value is at or above the laboratory’s positive cutoff (typically ≥1.10) — indicates that antibodies to HSV-2 were detected in your blood. This may appear on lab reports as positive, reactive, high, or abnormal. These terms all indicate the same finding: HSV-2 antibodies were detected.

A high result means:

Your immune system has produced antibodies against HSV-2
You were exposed to HSV-2 at least 2–12 weeks before testing
The test does not determine when infection occurred, where the infection is located on the body, or whether the virus is currently active

How High Is “High”?

The index value affects how confidently the result is interpreted:

Index Value	Interpretation
1.10–3.50	Low positive — antibodies detected, but false-positive rates can be significant. CDC recommends confirmatory testing in this range
Greater than 3.50	Positive — substantially more likely to represent true HSV-2 infection
8.0, 23, 40, or higher	Strong antibody response. The number itself does not indicate severity, contagiousness, or how recently infection occurred

Low positive results (1.10–3.50) are especially important to interpret carefully because false-positive results can occur, particularly in people without symptoms or in lower-prevalence populations.

Low Positive Results and False Positives

This is one of the most important aspects of HSV-2 IgG interpretation.

The HerpeSelect HSV-2 IgG ELISA — one of the most commonly used screening assays in the United States — has been shown to produce false-positive results at lower index values. CDC STI Treatment Guidelines note that the test “often is falsely positive at low index values (1.1–3.0).”

One large study reported specificity as low as 39.8% for index values between 1.1 and 2.9.

Practical interpretation:

Index 1.10–1.99: False positives are relatively common. Confirmatory testing is strongly recommended
Index 2.00–3.49: False positives remain possible. Confirmatory testing is recommended
Index ≥3.50: Results are substantially more likely to represent true HSV-2 infection

If you have no symptoms and received a low positive result, do not assume the diagnosis is definitive without confirmation.

Confirmatory Testing Options

HSV-2 IgG Inhibition Assay (Quest)

A reflex confirmatory test that evaluates whether antibody binding can be inhibited by HSV-2 antigen. This helps distinguish true HSV-2 antibodies from cross-reacting HSV-1 antibodies. Quest commonly reflexes this test automatically when screening results fall between 1.10 and 6.00.

HSV Western Blot (University of Washington)

Considered the gold-standard confirmatory antibody test for HSV-2. Often used when screening or inhibition assay results remain unclear.

Biokit HSV-2 Rapid Assay

A second-line confirmatory immunoassay sometimes used to improve diagnostic specificity.

What to Do With a Confirmed Positive Result

If your result has been confirmed — or falls into a high-confidence range above 3.50 — practical next steps may include:

Discussing symptoms, transmission risk, and treatment options with your clinician
Considering suppressive antiviral therapy if outbreaks are frequent or transmission reduction is important
Learning about medications such as acyclovir, valacyclovir, and famciclovir, which can reduce outbreaks and lower transmission risk
Seeking prompt medical evaluation if you are pregnant, immunocompromised, or experiencing neurological symptoms

HSV-2 is common, manageable, and not considered life-threatening in healthy adults.

A positive HSV-2 IgG result means HSV-2 antibodies were detected in your blood, indicating past exposure to herpes simplex virus type 2. Low positive results (index 1.10–3.50) are sometimes false positives and the CDC recommends confirmatory testing in this range. Results above 3.50 are substantially more likely to represent true HSV-2 infection. HSV-2 is common, manageable, and not life-threatening in healthy adults.

At a Glance

Test purpose: Detects IgG antibodies specific to herpes simplex virus type 2 (HSV-2), indicating past or current infection
Type-specific: Distinguishes HSV-2 antibodies from HSV-1 antibodies (targets HSV-2 glycoprotein G2)
Used for: Confirming HSV-2 infection in patients with symptoms; screening in select clinical situations
Common assays: HerpeSelect ELISA, Roche Elecsys, DiaSorin LIAISON
Timing: Antibodies take 2–12 weeks to develop after infection
Caveat: Low positive results (1.10–3.50) often require confirmatory testing — false-positive rates can be high
Context: HSV-2 is common (~1 in 6 US adults aged 14–49) and a positive result is not a medical emergency

Reference ranges vary by laboratory and assay. Always interpret results with your healthcare provider.

HSV-2 IgG Index Value Interpretation

Index Value	Interpretation
Less than 0.90	Negative
0.90 – 1.09	Equivocal (repeat in 1–3 weeks)
1.10 – 3.50	Low positive (confirmatory testing recommended)
Greater than 3.50	Positive

What to Do Next

Based on your index value:

Index <0.90 — Negative. No HSV-2 antibodies detected. If you had a possible exposure less than 12 weeks ago, consider retesting.
Index 0.90–1.09 — Equivocal. Ask your provider to repeat the test in 1–3 weeks.
Index 1.10–3.50 — Low positive. Ask about confirmatory testing (HSV-2 IgG Inhibition Assay or Western blot) before treating this as a diagnosis.
Index >3.50 — Positive. Discuss symptoms, transmission risk, and treatment options with your clinician.

What Is the HSV-2 IgG Type-Specific Antibody Test?

The HSV-2 IgG type-specific antibody test is a blood test that looks for IgG antibodies your immune system produces in response to herpes simplex virus type 2 (HSV-2). It is called “type-specific” because it can distinguish HSV-2 antibodies from HSV-1 antibodies by detecting antibodies to a unique HSV-2 protein called glycoprotein G2 (gG-2).

If the test is positive, your immune system has made antibodies to HSV-2 at some point — meaning you have been exposed to the virus. It does not tell you when you were infected, where the infection is located on the body, or whether the virus is currently active.

The test result is usually reported as an “index value” or “screening index” — a number that reflects how much HSV-2 IgG antibody was detected. The higher the number above the cutoff, the more confident the laboratory is that the result represents true HSV-2 infection.

Routine HSV-2 serologic screening is not recommended for the general asymptomatic population by the USPSTF due to false-positive concerns and limited impact on outcomes, but testing may be appropriate in patients with recurrent genital symptoms, partners with HSV infection, or high-risk sexual exposure histories.

How to Read Your HSV-2 IgG Index Value

Most commercial laboratories in the US (Quest, Labcorp, and others) use one of these immunoassays: HerpeSelect HSV-2 ELISA, Roche Elecsys HSV-2, or DiaSorin LIAISON HSV-2. All three use a similar index value cutoff system:

Index Value	Interpretation	What It Means
Less than 0.90	Negative	No HSV-2 antibodies detected. If you were recently exposed, antibodies may not have developed yet — retest at 12 weeks.
0.90 – 1.09	Equivocal	Borderline result. Repeat testing in 1–3 weeks is usually recommended.
1.10 – 3.50	Low positive	Antibodies detected, but false-positive rate is significant. CDC recommends confirmatory testing (Western blot or inhibition assay).
Greater than 3.50	Positive	Antibodies detected. Results in this range are substantially more likely to represent true HSV-2 infection than low positive results.

Important: “Reactive” on your lab report means the same thing as “Positive.” “Non-reactive” means the same as “Negative.” Different labs use different terms but the interpretation is identical.

Common Phrases Seen on Lab Reports

Patient portals and lab reports use a variety of labels for this test. If you see any of the following, they refer to the same biomarker:

HSV 2 IGG, TYPE SPECIFIC AB
HSV-2 IGG, TYPE SPECIFIC AB
HSV 2 IGG TYPE SPEC
HSV 2 IGG TYPE SPECIFIC AB 0.90
HSV 2 IGG TYPE SPECIFIC AB 0.91
HSV 2 IGG TYPE SPECIFIC AB 1.09
HSV 2 IGG TYPE SPECIFIC AB 1.10
HSV 2 IGG TYPE SPECIFIC AB 8.0
HSV 2 IGG TYPE SPECIFIC AB REACTIVE
HSV 2 IGG TYPE SPEC NON REACTIVE
HSV-2 IGG TYPE SPECIFIC AB HIGH
HSV-2 IGG TYPE SPECIFIC AB ABNORMAL
HSV-2 IGG TYPE SPECIFIC AB EQUIVOCAL
HSV2 IGG HERPESELECT
HSV2 SCREENING INDEX
HSV-2 GLYCOPROTEIN G AB, IGG
HSV-2 IGG INHIBITION, IA
HSV 1/2 IGG, W/REFL HSV-2 INHIBITION

All of these are variants of the same type-specific IgG antibody test for HSV-2. The number after “AB” is your index value — see the index value interpretation table above.

Is a Positive HSV-2 IgG Result Dangerous?

No, a positive HSV-2 IgG result is not dangerous on its own. Here is what it actually means:

You have been exposed to HSV-2 at some point in the past (typically more than 2–12 weeks ago)
HSV-2 is extremely common. Roughly 1 in 6 adults aged 14 to 49 in the United States carry HSV-2 antibodies
Most people with HSV-2 either have no symptoms or have symptoms so mild they go unnoticed
HSV-2 is a chronic but manageable condition. Antiviral medications (acyclovir, valacyclovir, famciclovir) can reduce outbreaks and lower the risk of transmitting the virus to partners
HSV-2 does not affect life expectancy in healthy adults

The situations where HSV-2 requires closer medical attention are pregnancy (especially around delivery, due to risk of neonatal herpes), immunocompromised individuals, and rare neurological complications such as HSV encephalitis. If any of these apply to you, discuss your result with your doctor promptly.

What Does “Equivocal” Mean?

An equivocal result (index 0.90–1.09) sits between negative and positive. It is too high to confidently call negative, and too low to confidently call positive. Possible reasons include:

Recent infection where antibodies are still rising (early seroconversion)
A weak antibody response in a true negative person (background reactivity)
Cross-reaction with HSV-1 antibodies

The standard approach is to repeat the test in 1–3 weeks. If antibodies are truly rising due to recent infection, the index should climb meaningfully on retesting. If the value remains equivocal or drops, HSV-2 infection is unlikely.

How Long After Exposure Does HSV-2 IgG Turn Positive?

IgG antibodies take time to develop after HSV-2 infection. The typical timeline:

First 2 weeks: Most people test negative. The immune system has not yet produced detectable IgG
2–6 weeks: Some people begin to seroconvert. Sensitivity is still limited
6–12 weeks: Most people who are truly infected will have detectable IgG antibodies
12 weeks or more: Sensitivity reaches 80–98% depending on the assay

The CDC recommends repeat testing 12 weeks after suspected exposure if the initial test is negative. A negative result before 12 weeks does not rule out recent infection.

Once IgG antibodies develop, they persist for life. A previously positive HSV-2 IgG will remain positive on future tests — antibody levels do not “wear off” after treatment, and there is no test that can show the virus has been cleared because herpes is not cleared.

HSV-2 IgG vs HSV-2 IgM — Why IgM Is Not Recommended

You may have seen tests for HSV-2 IgM offered alongside or instead of IgG. The CDC explicitly recommends against using IgM tests to diagnose herpes. Reasons include:

IgM tests are not type-specific and cannot reliably distinguish HSV-1 from HSV-2
A positive IgM does not necessarily mean recent infection. Between 30% and 70% of people with recurrent HSV may test IgM positive during reactivation
A negative IgM does not rule out recent infection either

If you have an IgM result on your report, focus on the IgG result instead. If you only have an IgM result, ask your provider to repeat testing with a type-specific HSV IgG assay.

Related Tests and Next Steps

Tests that may be ordered alongside or after HSV-2 IgG include:

HSV-1 IgG, Type Specific Ab — Distinguishes oral vs genital herpes exposure history
HSV-2 IgG Inhibition Assay — Reflex confirmatory test for low positive index values
HSV PCR / HSV DNA test — Tests for active virus from a swab of a lesion; preferred during outbreaks
HSV Western Blot — Gold-standard confirmatory antibody test available through the University of Washington
Other STI screening — Depending on symptoms and exposure history, clinicians may recommend HIV, syphilis, chlamydia, or gonorrhea testing

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Frequently Asked Questions

What does "HSV 2 IgG, Type Specific Ab" mean on my lab report?

It is a blood test that looks for IgG antibodies specifically against herpes simplex virus type 2 (HSV-2), distinguishing them from HSV-1 antibodies. A positive result means you have been exposed to HSV-2 at some point.

What does "reactive" mean on an HSV-2 IgG result?

"Reactive" is another word for "positive." It means HSV-2 IgG antibodies were detected in your blood at or above the laboratory's cutoff (usually index ≥1.10). The two terms are interchangeable.

What does "non-reactive" mean on an HSV-2 IgG result?

"Non-reactive" means the same as "negative" — no HSV-2 IgG antibodies were detected at or above the cutoff (typically index <0.90). It indicates no past exposure detected, though recent infection within the last 12 weeks may not yet be detectable.

What does an HSV-2 IgG index value of 0.90 mean?

An index of 0.90 falls at the very bottom of the equivocal range (0.90–1.09). It is borderline — neither clearly negative nor positive. Repeat testing in 1–3 weeks is usually recommended.

What does an HSV-2 IgG index value of 0.91 mean?

An index of 0.91 is equivocal, just into the borderline range. It is not considered positive. Repeat testing in 1–3 weeks is recommended to clarify whether antibodies are rising (suggesting recent infection) or stable (more consistent with background reactivity).

What does an HSV-2 IgG index value of 1.09 mean?

An index of 1.09 sits at the top of the equivocal range, just below the positive cutoff of 1.10. It is not yet classified as positive. Repeat testing in 1–3 weeks is recommended to determine whether the value rises into the positive range.

What does an HSV-2 IgG index value of 1.10 mean?

An index of 1.10 just crosses into the low positive range (1.10–3.50). This indicates HSV-2 antibodies were detected, but the CDC recommends confirmatory testing at this level due to a high false-positive rate. Do not consider this a definitive diagnosis without follow-up testing.

What does an HSV-2 IgG index value of 3.50 mean?

An index of 3.50 sits at the boundary between the low positive and confident positive ranges. Values at this level and above are more reliable than lower values. Confirmatory testing may still be considered, especially in the absence of symptoms.

What does an HSV-2 IgG index value of 8.0, 23, or 40 mean?

Index values well above 3.50 indicate a strong antibody response and are substantially more likely to represent true HSV-2 infection. The specific number does not indicate severity of disease, how recently you were infected, or how contagious you are.

What does "low positive" mean for HSV-2 IgG?

A low positive result is an index value between 1.10 and 3.50. While technically above the positive cutoff, this range has a high false-positive rate on the HerpeSelect ELISA — some studies report up to 50% false positives in low-prevalence populations. The CDC recommends confirmatory testing (inhibition assay or Western blot) for results in this range.

What does "equivocal" mean for HSV-2 IgG?

An equivocal result is an index value between 0.90 and 1.09. It is borderline — neither clearly negative nor clearly positive. Possible causes include early seroconversion, weak background reactivity, or cross-reaction with HSV-1 antibodies. Repeat testing in 1–3 weeks is usually recommended.

Is HSV-2 IgG positive dangerous?

No, a positive HSV-2 IgG result is not dangerous on its own. It indicates past exposure to HSV-2, which is a common and manageable condition. About 1 in 6 US adults aged 14–49 are HSV-2 positive, and most have mild or no symptoms. Closer medical attention is warranted in pregnancy, immunocompromised states, or if symptoms suggest neurological involvement.

Can the HSV-2 IgG test be wrong?

Yes. Low positive results (index 1.10–3.50) on the HerpeSelect assay have a high false-positive rate — up to 50% in low-prevalence populations. The CDC recommends confirmatory testing (inhibition assay or Western blot) for low positive results. False negatives can occur within the first 12 weeks after exposure, before antibodies have developed.

What is the HSV-2 IgG Inhibition Assay?

It is a confirmatory test offered by Quest Diagnostics and other labs. It checks whether the antibodies your blood produces can be inhibited by HSV-2 antigen — a property of true HSV-2 antibodies. It is reflex-ordered automatically when an initial HSV-2 IgG screening result falls into the low positive range (typically 1.10–6.00).

How long after exposure does HSV-2 show up on an IgG test?

Most people develop detectable HSV-2 IgG antibodies within 2 to 12 weeks of infection. The CDC recommends repeat testing 12 weeks after suspected exposure if the initial test is negative.

If I have HSV-2 IgG antibodies, do I have herpes?

A confirmed positive HSV-2 IgG result indicates HSV-2 infection. However, low positive results (index 1.10–3.50) should be confirmed with a second test before being considered diagnostic. If symptoms are present, a PCR swab of the active lesion is the most reliable diagnostic test.

Will my HSV-2 IgG result ever turn negative?

No. Once you develop IgG antibodies to HSV-2, they persist for life. The antibody test cannot show that the virus has been "cleared" because HSV-2 establishes lifelong latent infection. Antiviral medications can suppress symptoms and reduce transmission but do not eliminate the virus.

What is the difference between HSV-2 IgG and HSV-2 IgM?

HSV-2 IgG antibodies develop within weeks of infection and persist for life — they are the standard test for past HSV-2 exposure. HSV-2 IgM antibodies appear earlier but are not type-specific, often cross-react between HSV-1 and HSV-2, and can be positive during recurrent outbreaks of old infections. The CDC recommends against IgM testing for HSV diagnosis.

Can HSV-1 cause a positive HSV-2 IgG result?

It can contribute to false-positive results, especially at low index values. The HSV-2 IgG type-specific assay is designed to target a unique HSV-2 protein (glycoprotein G2), but some cross-reactivity with HSV-1 antibodies occurs in practice. This is one reason confirmatory testing is recommended for low positive results.

Do I need to tell my partner if my HSV-2 IgG is positive?

A confirmed positive result indicates HSV-2 infection, which can be transmitted to partners even without visible symptoms (asymptomatic shedding). Disclosure is generally recommended in the context of sexual relationships. However, if your result is a low positive (1.10–3.50), pursue confirmatory testing first before making decisions about disclosure or treatment.

Does Valtrex (valacyclovir) lower HSV-2 IgG levels?

No. Antiviral medications like valacyclovir, acyclovir, and famciclovir suppress viral replication but do not affect the antibody levels in your blood. A positive HSV-2 IgG will remain positive regardless of antiviral treatment.

What does HSV-2 IgG supplemental test positive mean?

A supplemental or inhibition-positive HSV-2 result means confirmatory testing supported the original HSV-2 IgG screening result, making true HSV-2 infection substantially more likely.

Clinical Sources & References

All our content is backed by peer-reviewed studies, academic research, and trusted medical sources. We’re committed to accuracy and transparency — see our editorial policy for details.

Sexually Transmitted Infections Treatment Guidelines — Genital Herpes

Centers for Disease Control and Prevention · 2021 View source ↗
Screening for Genital Herpes

Centers for Disease Control and Prevention · 2024 View source ↗
Genital Herpes Infection: Serologic Screening

US Preventive Services Task Force · 2023 View source ↗
Herpes Simplex Virus Type 2 (HSV2) Western Blot Confirmatory Testing Among Men Testing Positive for HSV2 Using the Focus Enzyme-Linked Immunosorbent Assay in a Sexually Transmitted Disease Clinic

Journal of Clinical Virology · 2019 View source ↗
Use of "biokit HSV-2 Rapid Assay" to improve the positive predictive value of Focus HerpeSelect HSV-2 ELISA

BMC Infectious Diseases · 2005 View source ↗
Herpes Simplex Virus 2 (IgG), with Reflex to HSV-2 Inhibition

Quest Diagnostics · 2025 View source ↗

Article Review Log

Last reviewed May 13, 2026

Originally published May 13, 2026

Reviewed by HealthMatters Editorial Team

Written by Healthmatters Editorial Team

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HSV-2 IgG Type Specific Ab: Positive & Low Positive Results

How High Is “High”?

Low Positive Results and False Positives

Confirmatory Testing Options

HSV-2 IgG Inhibition Assay (Quest)

HSV Western Blot (University of Washington)

Biokit HSV-2 Rapid Assay

What to Do With a Confirmed Positive Result

At a Glance

HSV-2 IgG Index Value Interpretation

What to Do Next

What Is the HSV-2 IgG Type-Specific Antibody Test?

How to Read Your HSV-2 IgG Index Value

Common Phrases Seen on Lab Reports

Is a Positive HSV-2 IgG Result Dangerous?

What Does “Equivocal” Mean?

How Long After Exposure Does HSV-2 IgG Turn Positive?

HSV-2 IgG vs HSV-2 IgM — Why IgM Is Not Recommended

Related Tests and Next Steps

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