What does it mean when HSV-2 IgG is reactive?

"Reactive" is the laboratory term for a positive HSV-2 IgG result — it means HSV-2-specific antibodies were detected above the assay threshold. The index value determines how reactive the result is: 0.90–1.09 is equivocal (borderline), and ≥1.10 is positive (reactive). A "reactive abnormal" notation means the result is positive and outside the normal (negative) reference range. Reactive does not mean the infection is currently active — IgG antibodies indicate past exposure and persist for life once established. If the reactive result is in the low-positive range (index 1.10–3.5), confirmatory testing with the inhibition assay or Western blot is strongly recommended before accepting the diagnosis.

What does an equivocal HSV-2 result mean?

An equivocal result (index value 0.90–1.09) means the test signal is in the borderline zone — neither clearly positive nor clearly negative. Equivocal results should not be interpreted as a diagnosis of HSV-2 infection. The recommended next step is to repeat the test in 12 weeks using the same laboratory platform. On repeat, the result may resolve to negative (more likely if the initial value was at the low end of equivocal), remain equivocal, or turn clearly positive. If the repeat is equivocal or positive, confirmatory testing with the inhibition assay or University of Washington Western blot is appropriate.

What does a high HSV-2 index value mean — does a higher number mean worse disease?

A higher HSV-2 IgG index value indicates a stronger antibody signal — more antibodies are present in the blood. However, the index value does not determine how severe the infection is, how frequent outbreaks will be, or how contagious the person is. The index value reflects immune response magnitude, which varies from person to person and can change over time regardless of disease activity. A very high index value (above 6.0) is a reliable indicator that the result is a true positive, but it does not indicate that the infection is more serious than a low-positive result. Once established, HSV-2 antibodies can remain high for years or gradually decline — neither pattern has consistent clinical significance.

Can an HSV-2 IgG positive result become negative over time?

In true HSV-2 infection, IgG antibodies persist for life — a genuinely positive result does not become negative. However, low-positive results that later become negative on repeat testing are common, and this most often reflects a false positive initial result rather than the disappearance of true antibodies. This is one reason why repeat testing and confirmatory testing are important for low-positive values: a result that resolves to negative on repeat is more consistent with an initial false positive than with true infection. Rare exceptions include severe immunosuppression (such as advanced HIV disease or immunosuppressive medications) where antibody levels may decline, but this is uncommon and would typically occur alongside other significant clinical changes.

What is the HSV-2 IgG inhibition assay?

The HSV-2 IgG inhibition assay (also called "HSV-2 IgG inhibition IA" on lab reports) is a confirmatory test automatically performed by LabCorp when the initial HSV-2 IgG index value falls between 1.10 and 6.00. It works by pre-treating the blood sample with a competing HSV-2 antigen — if the initial antibodies are truly specific to HSV-2, they will be blocked (inhibited). A positive inhibition result confirms the initial positive. A negative inhibition result suggests the initial positive was likely a false positive. The inhibition assay is more specific than the initial ELISA, reducing false positive rates significantly. For definitive confirmation, particularly when the inhibition result is negative or equivocal, the University of Washington HSV-2 Western blot is the gold standard.

I tested positive for HSV-2 but I've never had any symptoms. Is this possible?

Yes — this is actually the most common situation for people with HSV-2. Studies show that only about 10–25% of HSV-2-infected individuals are aware of their infection. The majority have never had a recognizable outbreak or have had symptoms so mild or atypical (a brief itch, a small sore mistaken for a razor bump or ingrown hair) that they were not recognized as herpes. A positive HSV-2 IgG means past exposure has occurred and the virus is likely present in nerve tissue, but it does not mean you are currently experiencing an active outbreak. Asymptomatic viral shedding — where the virus is present on the skin without visible symptoms — does occur and can lead to transmission. If you have a confirmed positive result without symptoms, discussion with a clinician about antiviral suppressive therapy (which reduces shedding by approximately 50%) and transmission risk reduction is appropriate.

Can the HSV-2 IgG test tell when I got infected?

No — the HSV-2 IgG test cannot determine when an infection occurred. A positive IgG result confirms that exposure to HSV-2 happened at some point in the past, but the index value does not reveal whether infection occurred weeks, months, or years ago. Once established, IgG antibodies persist for life and the level can fluctuate independently of how long ago the infection occurred or how active the virus is. The only way to estimate timing is if a documented prior negative test establishes that seroconversion occurred in a specific interval, or if the positive result appears very shortly after a known exposure alongside new symptoms suggesting primary infection. Outside of these circumstances, a positive HSV-2 IgG simply confirms past exposure — not recent exposure.

¿Qué significa un resultado positivo de HSV-2 IgG? (What does a positive HSV-2 IgG result mean in Spanish?)

Un resultado positivo para el HSV-2 IgG (herpes simplex virus tipo 2, anticuerpos IgG) significa que el sistema inmune ha producido anticuerpos contra el virus del herpes tipo 2, lo que indica exposición pasada al virus. El resultado se reporta como un valor índice: menos de 0.90 es negativo, entre 0.90 y 1.09 es equívoco (se recomienda repetir la prueba en 12 semanas), y 1.10 o más es positivo. Importante: si el valor índice está entre 1.10 y 3.5, existe una tasa significativa de falsos positivos. Se recomienda una prueba confirmatoria (ensayo de inhibición o Western blot) antes de establecer un diagnóstico definitivo. Un resultado positivo sin síntomas es común — la mayoría de las personas con HSV-2 no reconocen síntomas.

HSV-2 IgG Test Results: Index Value Range, Reactive/Abnormal, and What High Numbers Mean

Serum

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Optimal Result: 0 - 0.9 Value.

HSV IgG Blood Test

From Healthmatters.io Team and reviewed by HM Editorial Team

Written on June 22, 2026 | Last updated Updated on June 22, 2026

Lab Results Explained and Tracked

QUICK ANSWER

The HSV-2 IgG test measures herpes simplex virus type 2 antibodies in the blood. The result is reported as an index value — a number that falls in one of three zones.

Index value	Zone	What it means
Below 0.90	Negative	No HSV-2 antibodies detected above threshold
0.90–1.09	Equivocal	Borderline — repeat testing in 12 weeks recommended
1.10 and above	Positive	HSV-2 antibodies detected — past exposure indicated

Important caveat: A positive result in the 1.10–3.5 range has a significant false positive rate. Confirmatory testing is recommended before a diagnosis is made.

Common questions at a glance:

Question	Short answer
What does "reactive/abnormal" mean?	"Reactive" and "abnormal" are lab report terms for a positive result — the index value is above the threshold
What does equivocal mean?	Borderline result (0.90–1.09) — the test cannot confirm positive or negative; repeat in 12 weeks
What does a high index value mean?	A higher index value generally indicates a stronger antibody signal, but the number itself doesn't determine severity of infection
Can the test give a false positive?	Yes — false positives are common in the 1.10–3.5 range; confirmatory testing is recommended
What is the reflex inhibition test?	A second test automatically run when the initial index is 1.10–6.00 to confirm whether the initial positive is true or false
I tested positive but have no symptoms — is this normal?	Yes — most HSV-2 infections are asymptomatic or unrecognized; a positive IgG means past exposure, not necessarily active disease

UNDERSTANDING YOUR HSV-2 INDEX VALUE — THE COMPLETE RANGE TABLE

The HSV-2 IgG test on the HerpeSelect ELISA (used by LabCorp and other major labs) reports results as an index value. Here is how to read the full range:

Index value	Zone	Interpretation	Recommended action
<0.90	Negative	No significant HSV-2 antibodies detected	No action needed; if recent exposure (<16 weeks), repeat testing to allow window period to close
0.90–1.09	Equivocal	Borderline — cannot confirm positive or negative	Repeat testing in 12 weeks with same platform
1.10–1.99	Low positive	Above threshold — confirmatory testing strongly recommended before diagnosis	HSV-2 IgG inhibition assay or Western blot
2.00–3.49	Low-moderate positive	Still in elevated false positive zone — confirmatory testing recommended	HSV-2 IgG inhibition assay or Western blot
3.50–5.99	Moderate positive	Lower false positive risk — inhibition reflex often still performed	Clinical correlation; inhibition assay if available
6.00–23.99	High positive	Well above threshold — true positive very likely	Clinical evaluation; partner notification discussion
≥24 (or ">23")	Very high positive	Markedly elevated — strong evidence of past HSV-2 infection	Clinical evaluation

What does "HSV-1 index value 40" or "HSV-2 index value 40" mean? Very high index values (above 23–40) are reported differently on different platforms — some LabCorp reports display the maximum value as ">23.00" when the actual signal exceeds the assay's measurement ceiling. A result of ">23" or "40" on the same report means the antibody signal is beyond the measurable range — it is a very strong positive, not a specific titer value.

WHAT DOES "REACTIVE" OR "ABNORMAL" MEAN ON MY REPORT?

Lab reports for HSV-2 IgG use different terminology depending on the laboratory platform. These terms all mean the same thing — the test is positive:

Term on your report	What it means
Reactive	Positive — antibodies detected above the threshold
Abnormal	Positive — result is outside the normal (negative) range
Reactive Abnormal	Positive — same as "reactive"
Positive	Positive — unambiguous
Out of Range	Positive — index value is above the reference range upper limit
H (with index number)	High — flagged as above the reference range; positive
Non-reactive	Negative — no antibodies detected above threshold
Negative	Negative
Equivocal	Borderline — neither clearly positive nor negative; see equivocal section

Why do labs use "reactive" instead of "positive"? The term "reactive" is standard in serology reporting because antibody tests detect a reaction rather than directly detecting the organism. "Reactive" does not mean the infection is currently active — it means your blood reacted with the test antigen.

WHAT DOES AN EQUIVOCAL RESULT MEAN?

An equivocal HSV-2 IgG result (index value 0.90–1.09) means the test signal is in the borderline zone — too close to the cutoff to be classified as clearly positive or negative.

What to do with an equivocal result:

Repeat the test in 12 weeks using the same laboratory platform (consistency is important for comparison)
If the repeat result is still equivocal or turns positive, confirmatory testing with the inhibition assay or Western blot is appropriate
An equivocal result alone should not be used to make a diagnosis of HSV-2 infection
Equivocal results in the 0.90–1.09 range may represent very early seroconversion (if tested within the first weeks of exposure), a true borderline result that may resolve to negative, or a very weak true positive

Common specific equivocal values:

0.90: At the exact lower boundary of equivocal — earliest possible positive signal
0.91: Marginally equivocal — clinically equivalent to 0.90; repeat testing recommended
1.00–1.09: Equivocal zone — cannot classify without repeat testing

MOST COMMON HSV-2 IgG INDEX VALUES — EXACT LOOKUP

Index value	Zone	Interpretation
<0.90	Negative	No HSV-2 antibodies above threshold
0.90	Equivocal	At the exact lower boundary — repeat in 12 weeks
0.91	Equivocal	Marginally equivocal — clinically the same as 0.90
1.00–1.09	Equivocal	Mid-equivocal zone — repeat testing needed
1.10–1.50	Low positive	Highest false positive zone — confirmatory testing essential
1.20	Low positive	Confirmatory testing strongly recommended before diagnosis
2.50	Low positive	Still in elevated false positive range — confirmatory testing recommended
3.50	Borderline transition	Lower false positive risk above this point; inhibition reflex still typical
5.52–5.99	Moderate positive	Inhibition reflex performed; most true positives
6.00	High positive	Well above threshold — true positive very likely
14.00	High positive	Markedly elevated; true positive
23.00 / ">23.00"	Very high positive	Assay ceiling — result reported as ">23" when signal exceeds measurable range
40+ (some platforms)	Very high positive	Same as ">23" — assay reporting maximum; not a specific titer

Why exact values matter: Many users search their precise index value (e.g., "0.91 HSV-2 results," "HSV-2 index value 5.52," "HSV-2 index 23"). The table above provides direct interpretation for the most commonly searched values.

THE FALSE POSITIVE PROBLEM — THE MOST IMPORTANT CLINICAL NUANCE

The HSV-2 IgG ELISA has a known and clinically significant false positive rate, particularly in the low-positive range. This is one of the most important facts for anyone who has received a low-positive HSV-2 IgG result to understand.

What the evidence shows: False positives are well documented in the 1.10–3.5 index value range. Studies using Western blot as the confirmatory reference standard have found that a significant proportion of results in this range do not reflect true HSV-2 infection, particularly in populations with lower HSV-2 prevalence. This is why confirmatory testing is recommended before establishing a diagnosis based on a low-positive ELISA result alone. The false positive concern diminishes substantially at higher index values.

Why does this happen? The HerpeSelect IgG ELISA can produce low-level reactions in people who have antibodies to related antigens (cross-reactivity), in people with other viral infections, or due to non-specific assay variation. The lower the index value, the higher the likelihood that the result is a false positive.

The false positive risk by index value range:

Index value range	False positive risk	What this means
1.10–1.99	Highest — confirmatory testing essential	A significant proportion of results in this range are false positives; do not diagnose without confirmation
2.00–3.49	Still elevated — confirmatory testing recommended	Lower false positive rate than 1.10–1.99 but still meaningful
3.50–5.99	Lower — inhibition reflex still often performed	Majority are true positives but inhibition assay adds confidence
≥6.00	Very low	Results at this level are almost always true positives

What to do: The most important step for anyone with a low-positive HSV-2 IgG result (index 1.10–3.5) is confirmatory testing before accepting the diagnosis. The two main options are the HSV-2 IgG inhibition assay (automatically reflexed by LabCorp for index values 1.10–6.00) and the University of Washington HSV-2 Western blot (the gold standard confirmatory test, ordered separately).

HOW LIKELY IS IT THAT MY RESULT IS A TRUE POSITIVE?

Index value	Likelihood of true positive	Recommended action
1.10–1.50	Lower — false positives are common in this range	Confirmatory testing essential before accepting diagnosis
1.51–3.50	Moderate — false positives still occur	Confirmatory testing strongly recommended
3.51–6.00	Higher — most are true positives, but confirmation adds confidence	Inhibition reflex typically performed; Western blot if any doubt
>6.00	High — true positive very likely	Clinical evaluation; confirmatory testing usually not required

This table reflects clinical guidance rather than a fixed mathematical probability — individual results depend on population prevalence, cross-reactivity factors, and assay variation. These categories align with how most infectious disease clinicians approach HSV-2 IgG interpretation.

THE HSV-2 IgG INHIBITION ASSAY — WHAT IT IS AND WHY IT MATTERS

When the initial HSV-2 IgG index value falls between 1.10 and 6.00 on the LabCorp platform, a second confirmatory test — the HSV-2 IgG Inhibition Assay (IA) — is automatically performed on the same sample. This is called a "reflex" test.

How the inhibition assay works: The sample is pre-treated with a competing HSV-2 antigen. If the antibodies in the sample are truly specific to HSV-2, they will be blocked (inhibited) by the competing antigen, causing the signal to drop. If the initial signal was not due to true HSV-2 antibodies (i.e., a false positive), the signal will not be significantly inhibited.

Inhibition assay result	Meaning
Positive	The inhibition confirms HSV-2 antibodies are present — initial positive is supported
Negative / Not confirmed	Inhibition does not support the initial positive — likely false positive; consider Western blot
Equivocal	Inconclusive — Western blot may be needed

If the inhibition assay is negative after a positive ELISA index: This is a strong indication that the initial positive was a false positive. Many clinicians will recommend the University of Washington Western blot for definitive clarification.

Why does this appear on my lab report? If your report shows "HSV-2 IgG Inhibition IA" as a second line item, it means the reflex test was automatically performed because your initial index value was between 1.10 and 6.00.

MOST COMMON HSV-2 IgG RESULTS

Index value	Category	Typical interpretation
<0.90	Negative	No HSV-2 antibodies detected
0.90	Equivocal (low)	At borderline — repeat in 12 weeks
0.91	Equivocal	Marginally equivocal — clinically same as 0.90
1.00–1.09	Equivocal (mid-range)	Borderline — repeat testing needed
1.10–1.99	Low positive	Highest false positive zone — confirmatory testing essential
2.00–3.49	Low-moderate positive	Elevated false positive zone — confirmatory testing recommended
3.50–5.99	Moderate positive	Inhibition reflex typically performed; most are true positives
6.00–23.99	High positive	True positive very likely; clinical evaluation
>23 or ">23.00"	Very high positive	Assay ceiling exceeded — markedly elevated; true positive

LOW POSITIVE VS HIGH POSITIVE — KEY DIFFERENCES

Feature	Low positive (index 1.10–3.5)	High positive (index >6.0)
False positive risk	Meaningful — well documented in this range	Very low — results at this level are almost always true positives
Confirmatory testing	Strongly recommended before accepting diagnosis	Usually not required
Diagnostic confidence	Lower — cannot reliably confirm without additional testing	High
Inhibition reflex	Automatically performed (LabCorp, index 1.10–6.00)	Not performed (index exceeds reflex range)
Clinical approach	Confirm before counseling or treatment decisions	Proceed with clinical evaluation and management

HSV-1 AND HSV-2 RESULTS TOGETHER — WHAT YOUR COMBINATION MEANS

Many patients receive both HSV-1 IgG and HSV-2 IgG results on the same panel. Interpreting them together adds important context:

HSV-1 IgG	HSV-2 IgG	Most likely interpretation
Positive	Negative	Very common — most HSV-1 is oral (cold sore exposure); does not indicate genital herpes
Positive	Low positive (1.10–3.5)	The presence of HSV-1 antibodies slightly increases the chance the HSV-2 result is a false positive due to cross-reactivity; confirmatory testing is especially important
Positive	High positive (>6.0)	Exposure to both HSV-1 and HSV-2 is likely; each virus can be present independently
Negative	Positive (any level)	No HSV-1 immunity; HSV-2 exposure likely — confirmatory testing still appropriate for low positive values
Negative	Negative	No current IgG antibodies to either type detected
Equivocal	Equivocal	Both borderline — repeat testing in 12 weeks for both

Important note on cross-reactivity: HSV-1 and HSV-2 share approximately 50% genetic sequence homology. High HSV-1 antibody levels can occasionally produce low-level cross-reactive signals on the HSV-2 assay. This is one reason why low-positive HSV-2 results in patients with strongly positive HSV-1 results should always be confirmed.

I TESTED POSITIVE FOR HSV-2 BUT HAVE NO SYMPTOMS — WHAT DOES THIS MEAN?

This is one of the most common and anxiety-provoking situations for people who receive an HSV-2 IgG positive result.

The most important fact: The majority of people with HSV-2 infection do not recognize symptoms. Studies consistently show that only approximately 10–25% of HSV-2-seropositive individuals are aware of their infection. Most people with HSV-2 have either never had a recognizable outbreak or have had symptoms that were too mild or atypical to be recognized as herpes.

What a positive HSV-2 IgG means in an asymptomatic person:

Past exposure to HSV-2 has occurred — the immune system has mounted an antibody response
The virus may be present in nerve ganglia and can reactivate
Asymptomatic viral shedding occurs — the virus can be transmitted even without visible symptoms
It does not mean you are currently having an active outbreak

What to do:

If the result is low-positive (index 1.10–3.5): pursue confirmatory testing before accepting the diagnosis
If confirmed positive: discuss with a clinician about transmission risk, suppressive antiviral therapy (which reduces shedding and transmission risk), and partner notification
Antiviral medications (acyclovir, valacyclovir, famciclovir) are effective at reducing outbreak frequency and transmission risk

TRANSMISSION RISK TO PARTNERS — KEY FACTORS:

Situation	Transmission risk
Confirmed positive, no symptoms, no antivirals	Present due to asymptomatic shedding — virus is transmitted without visible symptoms
Confirmed positive, daily suppressive antivirals	Meaningfully reduced — antivirals decrease asymptomatic shedding by approximately 50%
Confirmed positive, condoms + daily antivirals	Lowest — combination approach provides the greatest risk reduction
Active outbreak (symptomatic episode)	Highest — avoid sexual contact during outbreaks and for several days after
Low-positive result before confirmatory testing	Uncertain — confirmatory testing should occur before counseling on transmission risk

TIMING AND THE WINDOW PERIOD

The HSV-2 IgG test has an important limitation related to timing:

Time since exposure	IgG result interpretation
0–4 weeks	Antibodies typically not yet detectable — a negative result does not exclude recent infection
4–12 weeks	Antibodies developing — test may be false negative; repeat testing recommended
12–16 weeks	Most infected individuals have detectable IgG antibodies by this point
>16 weeks	A negative result provides strong (but not absolute) evidence against past HSV-2 infection

If you had a potential exposure within the past 12–16 weeks and the test is negative: The result should be repeated 12–16 weeks after the exposure before concluding negative status.

If you had a positive result within weeks of a known exposure: This could represent very early seroconversion (confirming recent infection) or a false positive — timing interpretation is important.

WHEN SHOULD I REPEAT THE HSV-2 IgG TEST?

Situation	Repeat testing?	Timing
Exposure less than 12 weeks ago + negative result	Yes	Repeat at ≥12–16 weeks post-exposure
Equivocal result (0.90–1.09)	Yes	Repeat in 12 weeks using same laboratory platform
Low positive (1.10–3.5) without confirmatory testing	Yes	Request inhibition assay or Western blot before accepting diagnosis
Low positive + negative inhibition assay	Consider Western blot	University of Washington HSV-2 Western blot for definitive resolution
High positive (>6.0) with confirmatory test	Usually no	Result is reliably positive; retesting adds little diagnostic value
Monitoring known infection over time	Not routinely needed	Antibody levels fluctuate and do not reliably track disease activity

Always use the same laboratory platform when repeating. Switching between assays (e.g., LabCorp HerpeSelect to Quest BioKit) can produce different index values that are not directly comparable, complicating interpretation.

WHAT TYPICALLY HAPPENS NEXT — CLINICIAN ACTION BY RESULT:

Result	Typical next clinical step
Negative (<0.90)	No action needed; if recent exposure, schedule repeat at 12–16 weeks
Equivocal (0.90–1.09)	Repeat testing in 12 weeks using same platform
Low positive (1.10–3.5)	Confirmatory testing — inhibition assay or Western blot before diagnosis
Confirmed positive — all levels	Counseling on transmission risk; discuss suppressive antiviral therapy; partner notification
High positive (>6.0), no confirmation needed	Clinical evaluation; counseling; antiviral discussion
Positive + inhibition negative	Likely false positive — Western blot for definitive resolution; do not diagnose based on ELISA alone

IgG VS IgM — THE KEY DISTINCTION

Feature	IgG Antibody	IgM Antibody
What it indicates	Past or established infection — exposure occurred at some point	Theoretically indicates recent/acute infection
Reliability	High for HSV-2 IgG type-specific tests	Low — IgM herpes tests are unreliable; high false positive and cross-reactivity rates
Recommended for HSV-2 diagnosis	Yes — type-specific IgG is the standard	No — CDC and most guidelines do not recommend IgM testing for herpes diagnosis
Duration of positivity	Lifelong — IgG antibodies persist indefinitely	Short-lived (weeks to months) — but HSV IgM is often persistently positive due to test unreliability

If your report shows "HSV-2 IgM positive": This result should be interpreted with caution. HSV IgM testing is known to be unreliable due to high rates of false positives and cross-reactivity with other herpes viruses (including the common CMV and EBV viruses). Most clinicians and guidelines rely on IgG type-specific testing, not IgM, for HSV-2 diagnosis.

FAQ about HSV 2 IGG Screening Index

What does it mean when HSV-2 IgG is reactive?

"Reactive" is the laboratory term for a positive HSV-2 IgG result — it means HSV-2-specific antibodies were detected above the assay threshold. The index value determines how reactive the result is: 0.90–1.09 is equivocal (borderline), and ≥1.10 is positive (reactive). A "reactive abnormal" notation means the result is positive and outside the normal (negative) reference range. Reactive does not mean the infection is currently active — IgG antibodies indicate past exposure and persist for life once established. If the reactive result is in the low-positive range (index 1.10–3.5), confirmatory testing with the inhibition assay or Western blot is strongly recommended before accepting the diagnosis.
What does an equivocal HSV-2 result mean?

An equivocal result (index value 0.90–1.09) means the test signal is in the borderline zone — neither clearly positive nor clearly negative. Equivocal results should not be interpreted as a diagnosis of HSV-2 infection. The recommended next step is to repeat the test in 12 weeks using the same laboratory platform. On repeat, the result may resolve to negative (more likely if the initial value was at the low end of equivocal), remain equivocal, or turn clearly positive. If the repeat is equivocal or positive, confirmatory testing with the inhibition assay or University of Washington Western blot is appropriate.
What does a high HSV-2 index value mean — does a higher number mean worse disease?

A higher HSV-2 IgG index value indicates a stronger antibody signal — more antibodies are present in the blood. However, the index value does not determine how severe the infection is, how frequent outbreaks will be, or how contagious the person is. The index value reflects immune response magnitude, which varies from person to person and can change over time regardless of disease activity. A very high index value (above 6.0) is a reliable indicator that the result is a true positive, but it does not indicate that the infection is more serious than a low-positive result. Once established, HSV-2 antibodies can remain high for years or gradually decline — neither pattern has consistent clinical significance.
Can the HSV-2 IgG test give a false positive?

Yes — false positives are well documented with the HSV-2 IgG ELISA (HerpeSelect) in the low-positive index value range (1.10–3.5). Studies using Western blot as the confirmatory reference standard have found that a meaningful proportion of results in this range do not reflect true HSV-2 infection, particularly in populations with lower HSV-2 prevalence. The false positive concern diminishes substantially at higher index values (above 3.5–6.0). This is why confirmatory testing with the HSV-2 IgG inhibition assay (automatically reflexed by LabCorp for index values 1.10–6.00) or the University of Washington Western blot is strongly recommended for anyone with a low-positive result. A diagnosis of HSV-2 should not be made based on a low-positive ELISA alone.
Can an HSV-2 IgG positive result become negative over time?

In true HSV-2 infection, IgG antibodies persist for life — a genuinely positive result does not become negative. However, low-positive results that later become negative on repeat testing are common, and this most often reflects a false positive initial result rather than the disappearance of true antibodies. This is one reason why repeat testing and confirmatory testing are important for low-positive values: a result that resolves to negative on repeat is more consistent with an initial false positive than with true infection. Rare exceptions include severe immunosuppression (such as advanced HIV disease or immunosuppressive medications) where antibody levels may decline, but this is uncommon and would typically occur alongside other significant clinical changes.
What is the HSV-2 IgG inhibition assay?

The HSV-2 IgG inhibition assay (also called "HSV-2 IgG inhibition IA" on lab reports) is a confirmatory test automatically performed by LabCorp when the initial HSV-2 IgG index value falls between 1.10 and 6.00. It works by pre-treating the blood sample with a competing HSV-2 antigen — if the initial antibodies are truly specific to HSV-2, they will be blocked (inhibited). A positive inhibition result confirms the initial positive. A negative inhibition result suggests the initial positive was likely a false positive. The inhibition assay is more specific than the initial ELISA, reducing false positive rates significantly. For definitive confirmation, particularly when the inhibition result is negative or equivocal, the University of Washington HSV-2 Western blot is the gold standard.
I tested positive for HSV-2 but I've never had any symptoms. Is this possible?

Yes — this is actually the most common situation for people with HSV-2. Studies show that only about 10–25% of HSV-2-infected individuals are aware of their infection. The majority have never had a recognizable outbreak or have had symptoms so mild or atypical (a brief itch, a small sore mistaken for a razor bump or ingrown hair) that they were not recognized as herpes. A positive HSV-2 IgG means past exposure has occurred and the virus is likely present in nerve tissue, but it does not mean you are currently experiencing an active outbreak. Asymptomatic viral shedding — where the virus is present on the skin without visible symptoms — does occur and can lead to transmission. If you have a confirmed positive result without symptoms, discussion with a clinician about antiviral suppressive therapy (which reduces shedding by approximately 50%) and transmission risk reduction is appropriate.
Can the HSV-2 IgG test tell when I got infected?

No — the HSV-2 IgG test cannot determine when an infection occurred. A positive IgG result confirms that exposure to HSV-2 happened at some point in the past, but the index value does not reveal whether infection occurred weeks, months, or years ago. Once established, IgG antibodies persist for life and the level can fluctuate independently of how long ago the infection occurred or how active the virus is. The only way to estimate timing is if a documented prior negative test establishes that seroconversion occurred in a specific interval, or if the positive result appears very shortly after a known exposure alongside new symptoms suggesting primary infection. Outside of these circumstances, a positive HSV-2 IgG simply confirms past exposure — not recent exposure.
¿Qué significa un resultado positivo de HSV-2 IgG? (What does a positive HSV-2 IgG result mean in Spanish?)

Un resultado positivo para el HSV-2 IgG (herpes simplex virus tipo 2, anticuerpos IgG) significa que el sistema inmune ha producido anticuerpos contra el virus del herpes tipo 2, lo que indica exposición pasada al virus. El resultado se reporta como un valor índice: menos de 0.90 es negativo, entre 0.90 y 1.09 es equívoco (se recomienda repetir la prueba en 12 semanas), y 1.10 o más es positivo. Importante: si el valor índice está entre 1.10 y 3.5, existe una tasa significativa de falsos positivos. Se recomienda una prueba confirmatoria (ensayo de inhibición o Western blot) antes de establecer un diagnóstico definitivo. Un resultado positivo sin síntomas es común — la mayoría de las personas con HSV-2 no reconocen síntomas.

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What does it mean if your HSV 2 IGG Screening Index result is too high?

A positive or reactive HSV-2 IgG result means antibodies to herpes simplex virus type 2 were detected in the blood above the assay threshold, indicating past exposure to HSV-2. The result is reported as an index value: values at or above 1.10 are classified as positive. However, the clinical interpretation of a positive result depends critically on the index value — false positives are well documented for low-positive results (index 1.10–3.5), which is why confirmatory testing with the HSV-2 IgG inhibition assay (automatically reflexed by LabCorp for index values 1.10–6.00) or the University of Washington Western blot is strongly recommended before accepting a low-positive diagnosis. High-positive results (index above 6.0) are far less likely to be false positives. A positive result without recognized symptoms is common — the majority of HSV-2-infected individuals do not recognize their infection, and a positive IgG indicates past exposure, not necessarily an active current outbreak.

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What does it mean if your HSV 2 IGG Screening Index result is too low?

A negative HSV-2 IgG result (index value below 0.90) means HSV-2 antibodies were not detected above the assay threshold. This generally indicates no prior HSV-2 infection. However, a negative result does not exclude very recent infection — HSV-2 IgG antibodies typically take 12–16 weeks to reach detectable levels after initial exposure (the window period). If you had a potential exposure within the past 12–16 weeks and the test is negative, repeat testing at least 12 weeks after the exposure is recommended before concluding negative HSV-2 status. A negative result in the absence of recent exposure or symptoms is reliably negative. Additionally, it is important to note that a negative HSV-2 blood test does not rule out HSV-1 as a cause of genital herpes — HSV-1 is increasingly common as a cause of genital herpes and is tested separately.

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HSV-2 IgG Test Results: Index Value Range, Reactive/Abnormal, and What High Numbers Mean

QUICK ANSWER

UNDERSTANDING YOUR HSV-2 INDEX VALUE — THE COMPLETE RANGE TABLE

WHAT DOES "REACTIVE" OR "ABNORMAL" MEAN ON MY REPORT?

WHAT DOES AN EQUIVOCAL RESULT MEAN?

MOST COMMON HSV-2 IgG INDEX VALUES — EXACT LOOKUP

THE FALSE POSITIVE PROBLEM — THE MOST IMPORTANT CLINICAL NUANCE

THE HSV-2 IgG INHIBITION ASSAY — WHAT IT IS AND WHY IT MATTERS

MOST COMMON HSV-2 IgG RESULTS

LOW POSITIVE VS HIGH POSITIVE — KEY DIFFERENCES

HSV-1 AND HSV-2 RESULTS TOGETHER — WHAT YOUR COMBINATION MEANS

I TESTED POSITIVE FOR HSV-2 BUT HAVE NO SYMPTOMS — WHAT DOES THIS MEAN?

TIMING AND THE WINDOW PERIOD

WHEN SHOULD I REPEAT THE HSV-2 IgG TEST?

IgG VS IgM — THE KEY DISTINCTION

FAQ about HSV 2 IGG Screening Index

What does it mean when HSV-2 IgG is reactive?

What does an equivocal HSV-2 result mean?

What does a high HSV-2 index value mean — does a higher number mean worse disease?

Can the HSV-2 IgG test give a false positive?

Can an HSV-2 IgG positive result become negative over time?

What is the HSV-2 IgG inhibition assay?

I tested positive for HSV-2 but I've never had any symptoms. Is this possible?

Can the HSV-2 IgG test tell when I got infected?

¿Qué significa un resultado positivo de HSV-2 IgG? (What does a positive HSV-2 IgG result mean in Spanish?)

All Your Lab Results. One Simple Dashboard.

What does it mean if your HSV 2 IGG Screening Index result is too high?

Related Health Conditions

All Your Lab Results. One Simple Dashboard.

Import, Track, and Share Your Lab Results Easily

Import, Track, and Share Your Lab Results

What does it mean if your HSV 2 IGG Screening Index result is too low?

Related Biomarkers

Article Review & Sources

Bring All Your Lab Results Together — In One Place

Gather Your Lab History — and Finally Make Sense of It

Finally, Your Lab Results Organized and Clear

Advanced Plan

Unlimited Account

Pro Monthly

What's included in a Healthmatters membership

Import Lab Results from Any Source

See Your Health Timeline

Understand What Your Results Mean

Enter Your Lab Reports Yourself — Always Free Enter Your Lab Reports — Always Free

Visualize Your Results

Export Your Complete Lab History in a Single File Export Your Complete Lab History

Comprehensive Data Entry Service for Your Reports Data Entry Service for Your Reports

Securely Share With Anyone You Trust

Let Your Lab Results Tell the Full Story

Once your results are in one place, see the bigger picture — track trends over time, compare data side by side, export your full history, and share securely with anyone you trust.

Bring all your results together to compare, track progress, export your history, and share securely.

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