What this test measures
Varicella zoster virus (VZV) IgG is the long-lived antibody produced after natural chickenpox infection or after the varicella vaccine. The test measures these antibodies in serum and is used to confirm immunity to chickenpox / shingles. IgG develops within 2–4 weeks of infection or vaccination and generally remains detectable lifelong.
VZV is the same virus that causes chickenpox in childhood and shingles (herpes zoster) when it reactivates years or decades later in the same person — so prior chickenpox is required for a person to develop shingles.
Why it matters
Varicella vaccine is not part of India's Universal Immunisation Programme, so many Indian adults have either had chickenpox or are non-immune. Confirming VZV IgG matters in several real-world Indian scenarios:
1. Pre-employment for healthcare workers — non-immune staff are at higher risk and can transmit VZV to vulnerable patients (newborns, pregnant women, immunosuppressed). 2. Pre-pregnancy — chickenpox during pregnancy can cause congenital varicella syndrome (limb hypoplasia, scarring, eye and brain abnormalities) and severe maternal varicella pneumonia. Vaccination of non-immune women before conception eliminates this risk. 3. Pre-transplant and pre-chemotherapy — non-immune patients receive vaccination before immunosuppression begins. 4. Post-exposure — when adults of uncertain immunity are exposed, IgG status guides decisions on varicella zoster immune globulin (VZIG).
How to prepare
No fasting required. Wait at least 4–6 weeks after varicella vaccine before testing IgG.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Varicella Zoster IgG (AU/mL or Index)[1][2] | Positive (≥ assay cut-off) = immune | Non-immune. Healthcare workers, women planning pregnancy, and patients about to start immunosuppression should be offered the varicella vaccine (2 doses, 4–8 weeks apart). Avoid contact with cases meanwhile. | Immune from past chickenpox or vaccination. Re-infection is rare. Shingles can still develop later in life from the same virus reactivating — the shingles (zoster) vaccine is offered to adults 50+ even if VZV IgG is positive. |
VZV IgG vs VZV IgM
| Marker | Appears | Lasts | Tells you |
|---|---|---|---|
| IgM | 3–5 days after rash | 4–8 weeks | Active or recent chickenpox / shingles |
| IgG (this test) | 2–4 weeks after exposure / vaccine | Lifelong (usually) | Past infection or vaccine-induced immunity |
Frequently asked questions
Why would my doctor order this test?
Common reasons: pre-employment screening for healthcare workers, pre-pregnancy planning, pre-transplant or pre-chemotherapy assessment, and after a known exposure when your past chickenpox history is unclear.
I had chickenpox as a child — do I need the test?
A clear personal history of chickenpox is usually accepted as evidence of immunity. Testing is mainly done when the history is unclear or when documentation is required (employment, transplant).
Does shingles vaccine help if I have already had chickenpox?
Yes. The recombinant zoster vaccine (Shingrix) is recommended for adults aged 50 and over, even if they had chickenpox. It significantly reduces the risk of shingles and postherpetic neuralgia.
Is chickenpox vaccine available in India?
Yes — varicella vaccine is available in Indian private practice and is recommended by the Indian Academy of Pediatrics (IAP). It is not part of the government Universal Immunisation Programme schedule yet.
I am pregnant and was exposed to a child with chickenpox — what should I do?
See your obstetrician promptly. They will check your VZV IgG status. If non-immune, varicella zoster immune globulin (VZIG) may be given within 10 days of exposure to reduce maternal and fetal complications.
Can chickenpox come back twice?
Rarely — second episodes have been described but are uncommon. What is much more common is the same virus reactivating decades later as shingles (herpes zoster) in a localised painful rash.
How fast will the report come?
NABL-accredited Mumbai and Thane labs typically deliver VZV IgG reports within 24 hours.
Related Infectious Disease tests
Tests commonly ordered alongside VARICELLA ZOSTER VIRUS ANTIBODY - IGG, or that help interpret an unexpected result.
Sources & references
- CDC — Varicella (Chickenpox) Laboratory Tests · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — Chickenpox · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Varicella Zoster Virus · accessed 2026-05-30T00:00:00.000Z
- Indian Academy of Pediatrics (IAP) — Immunisation Schedule · accessed 2026-05-30T00:00:00.000Z
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