Home Biomarkers Varicella Zoster Ab IgG

Varicella Zoster Ab IgG

Viral infections Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Viral infections

Overview

Varicella Zoster Ab IgG measures IgG-class antibodies directed against the varicella‑zoster virus (VZV), the agent that causes chickenpox (varicella) and shingles (herpes zoster). The test determines prior exposure or immunity (natural infection or vaccination) rather than acute infection. It is used when someone has been exposed, before pregnancy or immunosuppressive therapy, or to document immunity in healthcare workers. Symptoms prompting testing include recent vesicular rash, dermatomal pain (suspected zoster), or known exposure in a susceptible person. Results vary by age: infants carry maternal IgG for several months, children and adults previously infected or vaccinated are usually IgG‑positive; older adults may show waning immunity. Gender has minimal direct effect.

Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Viral infections - Symptoms: recent rash, dermatomal pain, or known exposure; preconception/pregnancy screening - Diagnoses/monitoring: documents immunity, evaluates susceptibility, assists management after exposure - Abnormal levels: absence of IgG indicates susceptibility; unexpected high/seroconversion may indicate recent infection or vaccination - Biological meaning: low/negative = no protective IgG; high/positive = past infection/vaccination and probable immunity - Behaviors/lifestyle: recent vaccination raises IgG; immunosuppression may blunt response - Family history: household exposure to chickenpox or shingles increases need for testing

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Understanding Test Results

Values <0.9 (ELISA index) or <10 IU/mL: negative no detectable VZV IgG; individual is likely susceptible to primary varicella and should be counseled on exposure risks; pregnant women and immunocompromised patients are at higher risk and may need prophylaxis.
Values 0.9–1.1 (index) or near 10 IU/mL: equivocal repeat testing in 2–4 weeks or use a different assay.
Values ≥1.1 (index) or ≥10 IU/mL: positive past infection or vaccination consistent with immunity; usually protective against primary disease.
Very high IgG titres can follow recent infection or recent vaccination but do not reliably distinguish reactivation (zoster) from past immunity; IgM, rising titres, or avidity testing and clinical correlation help determine recent infection.
In infants, positive IgG may reflect maternal antibodies that wane by ~6–12 months.

Normal Range

≥1.1 (ELISA index) OR ≥10 IU/mL

FAQs

Q: What does a positive varicella IgG AB mean?

A: A positive varicella IgG antibody means you have had prior exposure to or vaccination against varicella‑zoster virus and are likely immune to chickenpox. IgG usually persists long‑term and suggests protection against new infection or severe disease. It does not distinguish natural infection from vaccination. If pregnant, immunocompromised, or unsure about immunity level, discuss interpretation and follow‑up with your healthcare provider.

Q: Is the varicella zoster virus serious?

A: Varicella zoster virus can be serious. It causes chickenpox, usually mild in children but potentially leading to pneumonia, encephalitis or severe bacterial skin infections, especially in newborns, pregnant people, older adults and immunocompromised individuals. The virus can reactivate years later as shingles, which may cause debilitating nerve pain (postherpetic neuralgia). Vaccination greatly reduces risk and complications.

Q: What is the range for varicella zoster virus AB IgG?

A: Typical lab reference ranges vary by assay. Common cutoffs are: negative <0.9 (or roughly <50–100 mIU/mL); equivocal 0.9–1.1 (≈50–165 mIU/mL); positive/protective >1.1 (≈>165 mIU/mL). Exact numeric ranges and units depend on the laboratory and test method, so always use the reference interval printed on your lab report for interpretation.

Q: How to treat varicella-zoster IgG?

A: Varicella‑zoster IgG indicates immunity no treatment is needed if positive. If IgG is negative (susceptible), offer varicella vaccination. After exposure, non‑immune high‑risk persons (pregnant women, neonates, immunocompromised) may receive varicella‑zoster immunoglobulin (VZIG). For active chickenpox or shingles, start antiviral therapy (acyclovir/valaciclovir) promptly. IgM tests detect acute infection; consult a clinician.

Q: What happens if you test positive for varicella?

A: If you test positive for varicella (chickenpox), you have an active, contagious infection. Isolate until all lesions have crusted (usually about 5 days after the rash appears). Management is mostly supportive—rest, fluids, paracetamol for fever, calamine or antihistamines for itching. Antiviral therapy (e.g., acyclovir) may be recommended for adults, pregnant women, newborns or immunocompromised people if started early. Seek urgent care for severe or respiratory/neuro symptoms and inform close contacts.

Q: What is the difference between varicella-zoster AB IgM and IgG?

A: Varicella‑zoster IgM indicates recent or acute infection—appearing within days of symptoms and usually fading after weeks—so a positive IgM suggests current or recent chickenpox/shingles. IgG appears later, persists long‑term, and indicates past infection or immunity (including vaccination). In reactivation (shingles) IgG is typically present; IgM may be absent or variable. Clinical context matters.