QUICK ANSWER
HSV-2 IgG detects antibodies to herpes simplex virus type 2. The test uses different terminology from standard "positive/negative" — here is what each result means:
| Result on your report | What it means |
|---|---|
| Non Reactive | No HSV-2 antibodies detected — the standard "negative" result |
| Reactive | HSV-2 antibodies detected — indicates prior exposure to HSV-2 |
| Reactive Abnormal | Same as Reactive — "Abnormal" is the lab flag; the meaningful word is "Reactive" |
| Equivocal | Borderline — the result is in the indeterminate range; a repeat test is needed |
| Positive | Same as Reactive — some labs use "Positive" instead of "Reactive" |
| Negative | Same as Non Reactive — some labs use "Negative" instead of "Non Reactive" |
Common questions at a glance:
| Question | Short answer |
|---|---|
| Does "Reactive" mean I have herpes? | It means HSV-2 antibodies were detected. The test has limitations — particularly at low index values — so clinical confirmation may be needed |
| Does "Non Reactive" mean I definitely don't have HSV-2? | Not with complete certainty — there is a window period after exposure where antibodies have not yet developed; retest if recent exposure |
| What does "HSV 2 IgG, Type Specific Ab — Reactive" mean? | This is the full lab report label for a positive HSV-2 IgG test result |
| What does equivocal mean on a herpes test? | The result fell in the borderline zone (typically index 0.90–1.09) — neither clearly positive nor negative; repeat testing required |
| Is a Reactive HSV-2 IgG always accurate? | No — false positives occur, especially at low index values (1.1–3.5); the supplemental/inhibition test can confirm |
WHAT IS "REACTIVE" AND "NON REACTIVE"? — READING YOUR RESULT
Most herpes IgG blood tests do not report simply "Positive" or "Negative." They use the terms Reactive and Non Reactive — which are serological terminology for the same concepts:
| Lab report term | Meaning | Clinical interpretation |
|---|---|---|
| Non Reactive | No antibodies detected above threshold | Negative — no evidence of prior HSV-2 exposure |
| Reactive | Antibodies detected above threshold | Positive — HSV-2 antibodies present; prior exposure indicated |
| Reactive / Abnormal | Same as Reactive — "Abnormal" is the lab system's flag | The word "Abnormal" means the result is outside the reference interval (Non Reactive); it does not indicate severity |
| Equivocal | Result in the borderline zone | Indeterminate — neither clearly positive nor negative; repeat testing needed |
| Reference Interval: Non Reactive | The normal/expected result for this test | If your result says something other than Non Reactive, antibodies were detected |
Why "Reactive" instead of "Positive"? Serology tests (tests that detect antibodies in serum/blood) conventionally use Reactive/Non Reactive rather than Positive/Negative because the reaction being measured is a chemical antibody-antigen reaction, not a binary present/absent finding. The terms are functionally equivalent.
YOUR HSV-2 IgG INDEX VALUE — WHAT DOES YOUR NUMBER MEAN?
Most labs report HSV-2 IgG as a numeric index value (also called an index ratio or signal-to-cutoff ratio), not just a word. This number tells you how far above or below the detection threshold your result falls:
| Index value | Result category | Interpretation |
|---|---|---|
| Below 0.90 | Non Reactive (Negative) | No HSV-2 antibodies detected; standard negative result |
| 0.90–1.09 | Equivocal | Borderline — in the indeterminate zone; cannot be interpreted as positive or negative; repeat in 4–6 weeks |
| 1.10–3.49 | Reactive (Low Positive) | Antibodies detected — but this range has a significant false positive rate; supplemental testing strongly recommended before clinical decisions are made |
| 3.50 and above | Reactive (Positive) | Antibodies detected at a level associated with true HSV-2 infection; false positives less common at this level |
The most important clinical fact about low positive results: Low-positive results (particularly index values in the 1.1–3.49 range) have substantially lower specificity and may require confirmatory testing because false positives are well documented in this range. The CDC and IDSA guidelines specifically note that index values below 3.5 may not indicate true HSV-2 infection and should be confirmed with a supplemental test (the HSV-2 Western Blot or the Inhibition/Biokit assay) before clinical conclusions are drawn.
What does 0.90 mean on an HSV test? An index value of exactly 0.90 falls at the bottom of the equivocal zone in most assays. Depending on your lab's specific cutoffs, this may be reported as Non Reactive (below 0.90) or Equivocal (0.90–1.09). Check your report's stated reference range — if 0.90 is listed as "Non Reactive" on your report, it is a negative result by that lab's criteria.
WHAT DOES REACTIVE MEAN? — HSV-2 IgG REACTIVE EXPLAINED
A Reactive HSV-2 IgG result means the test detected IgG antibodies to herpes simplex virus type 2 in your blood. IgG antibodies develop after exposure to HSV-2 — typically within 12 weeks of initial infection — and persist for life in people who have been infected.
What a Reactive result tells you:
- HSV-2 antibodies are present in your blood
- You have been exposed to HSV-2 at some point in your life
- The test cannot tell you when the infection occurred (could be recent or decades ago)
- The test cannot tell you whether the infection is active or producing symptoms
What a Reactive result does not tell you:
- Whether you currently have an active outbreak
- When you were first infected
- Whether you are likely to transmit the virus to a partner (transmission risk is separate from antibody status)
- Whether the result is accurate (particularly at low index values — see above)
Can a Reactive HSV-2 IgG result be wrong? Yes. False positives occur, particularly in:
- Low-index results (index value 1.10–3.49)
- People with other autoimmune conditions
- People who have received certain vaccines
- Labs using older ELISA assays
If your result is Reactive with an index value below 3.5 and you have no symptoms or known exposure history, confirmatory testing with the HSV-2 Western Blot (the gold standard) or Inhibition assay is strongly recommended before making clinical decisions.
WHAT DOES NON REACTIVE MEAN? — HSV-2 IgG NON REACTIVE EXPLAINED
A Non Reactive HSV-2 IgG result means the test did not detect HSV-2 antibodies above the threshold — this is the standard negative result.
What a Non Reactive result tells you:
- No HSV-2 IgG antibodies were detected at the time of testing
- This is the expected result for people who have not been exposed to HSV-2
What a Non Reactive result does not guarantee:
- That you have never been exposed — the test has a window period of approximately 12–16 weeks after initial infection before reliable antibodies develop
- If you had a potential exposure within the past 12–16 weeks, a Non Reactive result may not yet reflect a recent infection — retest at 12–16 weeks post-exposure for a reliable result
HSV-2 Non Reactive with symptoms? If you have symptoms that could be consistent with herpes (genital ulcers, blisters, sores) but your IgG blood test is Non Reactive, the discrepancy may be because:
- The infection is too recent for IgG antibodies to develop
- The symptoms are caused by HSV-1 (which requires a separate HSV-1 IgG test)
- The symptoms have a different cause entirely
- A swab test (PCR or culture) of an active lesion is more accurate than blood testing for diagnosing current outbreaks
WHAT DOES EQUIVOCAL MEAN ON AN HSV-2 TEST?
An Equivocal HSV-2 IgG result means the test fell in the borderline zone — too high to be clearly negative, but not high enough to be confidently called positive. This result cannot be interpreted as either positive or negative.
Standard equivocal ranges:
| Assay | Non Reactive | Equivocal | Reactive |
|---|---|---|---|
| HerpeSelect 2 IgG (Focus Diagnostics) | Below 0.90 | 0.90–1.09 | 1.10 and above |
| Roche Elecsys HSV-2 IgG | Below 0.90 | 0.90–1.09 | 1.10 and above |
| Biokit HSV-2 | Below 0.90 | 0.90–1.10 | Above 1.10 |
What does an equivocal result mean clinically?
Most equivocal HSV-2 IgG results resolve to Non Reactive (negative) on repeat testing. However, some represent true early seroconversion — the early period when antibodies are just beginning to develop after a new infection.
| Equivocal result scenario | What it likely means | What to do |
|---|---|---|
| No known exposure, no symptoms | Most commonly a non-specific reaction or borderline result | Repeat in 4–6 weeks; most resolve to Non Reactive |
| Known recent exposure (within 12 weeks) | Could represent early seroconversion | Repeat at 12–16 weeks post-exposure for definitive result |
| Symptoms consistent with herpes | Possible early infection | Swab test of active lesion is more diagnostic; repeat IgG in 6–8 weeks |
| Persistent equivocal on repeat testing | Requires clarification | HSV-2 Western Blot or Inhibition assay (supplemental test) is the next step |
THE SUPPLEMENTAL TEST — HSV-2 IgG INHIBITION ASSAY / WESTERN BLOT
When a low-positive or equivocal HSV-2 IgG result is unclear, a supplemental test is used to confirm or rule out the result. This is what "W/Refl HSV-2 Inhibition" means on your lab report — the lab automatically orders the supplemental test if the initial result falls in a specified range.
Two main supplemental tests:
| Test | How it works | What it tells you |
|---|---|---|
| HSV-2 Inhibition Assay (Biokit/Confirm) | Measures whether HSV-2-specific antigen inhibits the antibody signal — true positives are inhibited, false positives are not | Highly specific; used to distinguish true positives from false positives in the 1.1–3.5 index range |
| HSV-2 Western Blot (University of Washington) | The gold standard reference test; detects antibodies against specific HSV-2 proteins | Most accurate available test; used to resolve equivocal or low-positive IgG results; available through specialty labs |
What does "HSV-2 IgG Inhibition IA Positive" mean? The supplemental inhibition assay came back positive — meaning the low-positive IgG result was confirmed as a true positive, not a false positive. This significantly increases the likelihood that the initial reactive result reflects true HSV-2 infection.
What if the initial IgG is positive but the inhibition assay is negative? This pattern suggests the initial IgG result was likely a false positive. In this scenario, HSV-2 Western Blot testing may be recommended to provide a definitive answer.
IgG VS IgM — WHICH TEST IS WHICH?
Many people are confused about why they received an IgG test rather than an IgM test, or why both are ordered. Here is the key difference:
| Test | What it detects | When it appears | Clinical use |
|---|---|---|---|
| HSV-2 IgG | Long-lasting antibodies that develop after initial infection | Typically 12–16 weeks after initial infection; persist lifelong | Standard test for determining HSV-2 status; not useful for diagnosing very recent infection |
| HSV-2 IgM | Early antibodies that appear shortly after infection | Appears within days to weeks of infection; fades over time | Unreliable for herpes diagnosis — high false positive rate; cross-reactivity with HSV-1; NOT recommended by CDC or IDSA for HSV diagnosis |
Important: If your doctor ordered an HSV-2 IgM test, you should know this test is not recommended for routine herpes diagnosis due to poor specificity. A positive HSV-2 IgM result does not reliably indicate recent HSV-2 infection. The HSV-2 IgG is the clinically validated test.
TEST ACCURACY AND LIMITATIONS
The HSV-2 IgG test is useful but has important limitations that every patient should understand:
| Limitation | Details |
|---|---|
| Window period | Takes 12–16 weeks after infection for reliable IgG levels to develop; testing too early after exposure can produce a false negative |
| False positives at low index values | Low-positive index values (1.10–3.49) have substantially lower specificity and may require confirmatory testing because false positives are well documented in this range |
| Cannot determine timing | A Reactive result does not indicate when infection occurred — could be recent or from years or decades ago |
| Cannot predict symptoms | Many people with positive HSV-2 IgG never develop recognized symptoms; a positive test does not mean you will have outbreaks |
| Cannot assess transmissibility | Antibody status does not directly indicate current viral shedding or transmission risk |
| HSV-1 cross-reactivity | Very rare with type-specific (gG-based) assays; older non-type-specific assays can cross-react with HSV-1 antibodies |
| Assay variation | Different labs use different assays (HerpeSelect, Roche Elecsys, Biokit) with slightly different thresholds and performance characteristics |
WHAT DOES MY EXACT HSV-2 IgG INDEX VALUE MEAN?
| Your index value | Result category | Interpretation |
|---|---|---|
| Below 0.20 | Non Reactive | Clearly negative — well below threshold |
| 0.20–0.89 | Non Reactive | Negative — no HSV-2 antibodies detected |
| 0.90–1.09 | Equivocal | Borderline — repeat in 4–6 weeks; most resolve to negative |
| 1.10–1.49 | Reactive (Low Positive) | Low positive — specificity substantially lower in this range; confirmatory testing strongly recommended |
| 1.50–2.49 | Reactive (Low Positive) | Low positive — false positives well documented in this range; supplemental test or Western Blot recommended |
| 2.50–3.49 | Reactive (Low Positive) | Low positive — confirmatory testing still advised before clinical conclusions are drawn |
| 3.50–4.99 | Reactive | Above traditional confirmation threshold; more likely true positive, though confirmatory testing still available |
| 5.00–8.00 | Reactive | Higher positive — more reliable indication of true HSV-2 infection |
| Above 8.00 | Reactive (High Positive) | High positive — strong indication of HSV-2 infection; false positives uncommon at this level |
Important: The index value does not indicate how long you have been infected, how severe the infection is, or how likely you are to have outbreaks. Once in the Reactive range, the number itself has no additional clinical significance beyond distinguishing low-positive (confirmation recommended) from higher-positive (more reliable) ranges.
SEROCONVERSION TIMELINE — WHEN DOES THE TEST BECOME RELIABLE?
IgG antibodies take time to develop after initial HSV-2 infection. Testing too early after a potential exposure can produce a false negative even if infection occurred:
| Time after initial exposure | Likelihood of detectable IgG antibodies |
|---|---|
| 1–2 weeks | Usually Non Reactive even if infected — antibodies not yet developed |
| 4 weeks | Many people still Non Reactive — too early for reliable testing |
| 6–8 weeks | Majority of infected individuals beginning to seroconvert |
| 12 weeks | Most HSV-2 infections detectable by IgG testing |
| 16 weeks | Highly reliable — the recommended window for definitive testing after potential exposure |
| 6 months | Virtually all infections detectable — used in some guidelines as the final confirmation window |
Key implication: A Non Reactive result obtained within 12 weeks of a potential exposure does not definitively rule out HSV-2 infection. Retest at 16 weeks for a reliable result. A Non Reactive result obtained 4+ months after the most recent potential exposure is highly reliable.
HSV-1 + HSV-2 IgG COMBINED INTERPRETATION
Many patients receive both HSV-1 IgG and HSV-2 IgG results at the same time. Interpreting them together gives a more complete picture:
| HSV-1 IgG | HSV-2 IgG | Interpretation |
|---|---|---|
| Non Reactive | Non Reactive | No prior exposure to HSV-1 or HSV-2 detected |
| Reactive | Non Reactive | Prior HSV-1 exposure (most commonly oral herpes) — no evidence of HSV-2 |
| Non Reactive | Reactive | Prior HSV-2 exposure — no evidence of HSV-1 |
| Reactive | Reactive | Prior exposure to both HSV-1 and HSV-2 |
| Non Reactive | Equivocal | HSV-2 result is borderline — repeat; no prior HSV-1 detected |
| Reactive | Low Positive (1.10–3.49) | HSV-1 positive with low-positive HSV-2 — note: prior HSV-1 infection increases risk of false positive on some HSV-2 assays; confirmatory testing particularly important in this pattern |
Clinical note on HSV-1 and low HSV-2 positives: Prior HSV-1 infection can occasionally cross-react on some older or less specific HSV-2 assays, contributing to low-positive HSV-2 results. This is less common with modern type-specific (gG-based) assays but is worth noting if you have a clearly Reactive HSV-1 result alongside a low-positive HSV-2 result.
SYMPTOMS THAT MAY BE CONSISTENT WITH HSV-2
Many people with a Reactive HSV-2 IgG result have never had recognized symptoms — this is common. Others are trying to determine whether their symptoms could be herpes-related:
| Symptom | Consistent with HSV-2? | Notes |
|---|---|---|
| Painful genital blisters or vesicles | Yes — classic | Most characteristic presentation; may appear as small fluid-filled bumps |
| Genital ulcers or open sores | Yes — classic | Blisters that rupture leave shallow painful ulcers |
| Tingling, burning, or itching before an outbreak (prodrome) | Yes — highly characteristic | Many people recognize a warning sensation before lesions appear |
| Fever, body aches, headache (during first outbreak) | Yes — common with primary infection | Constitutional symptoms more prominent with initial infection than recurrences |
| Painful urination during outbreak | Yes — common | Urine contact with lesions or urethral involvement |
| Swollen lymph nodes in groin (during first outbreak) | Yes — common | Inguinal lymphadenopathy common with primary genital herpes |
| Recurrent pain or tingling in same area without visible lesions | Yes — subclinical reactivation | HSV-2 can reactivate without visible sores |
| Genital discharge alone (no lesions) | Not typical of HSV-2 alone | More commonly bacterial or yeast; discharge with lesions is possible |
| Urinary burning alone (no lesions) | Not specific | Could be UTI, urethritis, or other cause; not diagnostic of HSV-2 |
| No symptoms at all | Very common | Estimated 80% of HSV-2 seropositive individuals have unrecognized or asymptomatic infection |
Important: A positive HSV-2 IgG test cannot tell you whether your symptoms are caused by HSV-2. If you have active lesions, a swab or PCR test of the lesion is far more accurate for diagnosing the cause of a current outbreak than a blood antibody test.
MOST COMMON CLINICAL SCENARIOS
| Pattern | Most likely interpretation | Recommended next step |
|---|---|---|
| Non Reactive + no symptoms + no recent exposure | No HSV-2 antibodies; standard negative | Routine STI screening per guidelines |
| Non Reactive + recent potential exposure (within 12 weeks) | May be in window period | Retest at 12–16 weeks post-exposure |
| Reactive + index value above 3.5 + no prior testing | HSV-2 antibodies confirmed with high reliability | Discuss with doctor; consider antiviral suppression if indicated |
| Reactive + index value 1.10–3.49 + no symptoms | Low positive — false positive possible | Supplemental test (inhibition assay or Western Blot) before making clinical decisions |
| Equivocal (0.90–1.09) + no symptoms | Borderline — most likely to resolve to negative | Repeat IgG in 4–6 weeks; Western Blot if persistent |
| Reactive + symptoms of genital herpes | Positive test with consistent symptoms | Clinical diagnosis + IgG together; antiviral treatment appropriate |
| Non Reactive + active genital sores/blisters | Possible early infection or HSV-1 | Swab/PCR test of active lesion; HSV-1 IgG; repeat HSV-2 IgG in 12–16 weeks |
| HSV-2 IgG Reactive + Inhibition IA Positive | Supplemental test confirmed true positive | High confidence in HSV-2 diagnosis |
| HSV-2 IgG Reactive + Inhibition IA Negative | Supplemental test suggests false positive | HSV-2 Western Blot for definitive answer |
MOST COMMON HSV-2 IgG RESULTS
| Result on your report | Typical meaning |
|---|---|
| Non Reactive / 0.08 | Clearly negative — well below threshold |
| Non Reactive / 0.20 | Negative |
| Non Reactive / 0.70 | Negative — approaching but still below equivocal zone |
| Equivocal / 0.95 | Borderline — repeat in 4–6 weeks; most resolve to negative |
| Reactive / 1.20 | Low positive — confirmatory testing strongly recommended |
| Reactive / 2.00 | Low positive — false positives well documented; supplemental test recommended |
| Reactive / 3.20 | Low positive approaching confirmation threshold; supplemental testing still advised |
| Reactive / 4.00 | Positive above traditional 3.5 threshold; more reliable indication of true infection |
| Reactive / 8.00 | Strong positive — false positives uncommon at this level |
WHEN SHOULD I RETEST?
| Situation | When to retest |
|---|---|
| Possible exposure less than 12 weeks ago | Retest at 12–16 weeks post-exposure for reliable result |
| Equivocal result with no symptoms | Retest in 4–6 weeks — most equivocal results resolve to Non Reactive |
| Low-positive result (index 1.10–3.49) without symptoms or known exposure | Supplemental test (inhibition/Western Blot) rather than repeat standard IgG |
| Non Reactive result with ongoing symptoms | Swab test of active lesion; retest IgG if primary infection suspected |
| Confirmed positive — routine monitoring | Not required — IgG levels persist lifelong; repeat testing does not add clinical value |
Herpes Simplex 2 Ab, IgG
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Frequently Asked Questions
What does HSV 2 IgG, Type Specific Ab — Reactive mean?
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What does Reactive Abnormal mean on an HSV-2 test?
What does equivocal mean on a herpes test?
Is a Reactive HSV-2 IgG result always accurate?
What does the HSV-2 IgG supplemental test or inhibition assay mean?
What is the difference between HSV-1 and HSV-2 IgG tests?
Can I have HSV-2 and test Non Reactive?
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