Home Biomarkers Rubella Ab IgG

Rubella Ab IgG

Infectious diseases Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Infectious diseases

Overview

Rubella IgG measures the concentration of IgG antibodies directed against rubella (German measles) virus in blood. IgG appears after infection or vaccination and generally indicates past exposure and immunity; it does not diagnose acute infection (that requires IgM or PCR). The test is used to assess immunity status—especially in women planning pregnancy or who are pregnant—evaluate exposures after contact with a case, and screen newborns for maternal antibody. Results vary with age (children vaccinated in infancy/early childhood show IgG), pregnancy status (maternal IgG crosses the placenta), recent vaccination or infection (rising titres), and in immunocompromised people who may have lower or absent responses.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Infectious diseases (commonly included in prenatal and preconception screening panels) - Symptoms prompting test: rash, fever, lymphadenopathy after exposure, or evaluation following known contact with rubella - Conditions diagnosed/monitored: past infection or vaccine-induced immunity; evaluation for susceptibility in pregnancy to prevent congenital rubella - Reasons for abnormal levels: lack of prior infection/vaccination (low/negative IgG), recent infection or vaccination (rising IgG), waning immunity or poor vaccine response (low IgG) - Biological meaning: low/negative IgG = susceptible to infection; adequate IgG = likely immune/protected - Behaviors/factors: lack of vaccination, immunosuppression, or time since vaccination can affect levels - Family history: history of congenital rubella or household exposure may prompt testing

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Understanding Test Results

<5 IU/mL: Negative no protective IgG detected; person is susceptible to rubella and at risk if exposed (important for pregnant women).
5–9.9 IU/mL: Equivocal/indeterminate borderline result; repeat testing in 2–4 weeks or perform confirmatory testing (IgM or avidity) to assess recent exposure or seroconversion.
≥10 IU/mL: Positive/protective indicates past infection or successful vaccination and likely immunity.
Higher IgG alone typically reflects prior immunity; very high titres shortly after exposure or vaccination may reflect recent immune response.
Note: acute infection is suggested by IgM positivity or rising IgG titres on paired samples; in pregnancy, seroconversion from negative to positive during gestation indicates recent infection and risk for congenital rubella, requiring specialist evaluation.

Normal Range

≥10 IU/mL (protective/immune)

FAQs

Q: What does positive rubella ab IgG mean?

A: A positive rubella IgG means you have rubella-specific antibodies from past infection or vaccination and are considered immune. It suggests likely long-term protection and a low risk of congenital rubella if pregnant. It does not indicate recent or acute infection (that would show IgM). If pregnancy, borderline results, or exposure concerns exist, discuss confirmation and next steps with your clinician.

Q: What if rubella IgG is positive in pregnancy?

A: If rubella IgG is positive in pregnancy, it indicates immunity from past infection or vaccination and the risk of congenital rubella is very low. No specific treatment or pregnancy termination is required; routine antenatal care continues. If recent infection is a concern, check IgM. If non-immune, offer MMR vaccination after delivery.

Q: Is a positive IgG test good or bad?

A: A positive IgG generally means past exposure or vaccination and suggests some immune response, so it’s not inherently “bad.” It doesn’t prove current infection and may not guarantee full or long-lasting protection. Accuracy depends on timing, test quality and the specific disease; false results are possible. Clinical context and other tests are needed, so discuss results and next steps with your healthcare provider.

Q: What are 5 symptoms of rubella?

A: Five common symptoms of rubella are low‑grade fever; a pink or red blotchy rash that usually starts on the face and spreads; swollen, tender lymph nodes behind the ears and at the back of the neck; joint pain or stiffness (particularly in adults); and mild respiratory symptoms such as runny nose, cough, or conjunctivitis.

Q: How to avoid rubella during pregnancy?

A: Before pregnancy, confirm rubella immunity with blood testing and get MMR vaccination if non‑immune (wait at least 4 weeks after vaccination before conceiving). During pregnancy, avoid contact with people known or suspected to have rubella, practice strict hand hygiene, and avoid travel to outbreak areas. Do not receive MMR while pregnant. If exposed or symptoms occur, seek immediate medical evaluation and testing.

Q: Does rubella IgG positive mean immunity?

A: Rubella IgG positive generally indicates immunity from past infection or vaccination—protective antibodies are present. Laboratories use specific cutoff titres to define immunity; a positive IgG usually means you are not susceptible. It does not indicate recent infection (IgM does). In pregnancy, confirmed IgG positivity is reassuring; nonimmune women should avoid exposure and be offered MMR vaccination after delivery.