Immunity and viral serology . Patient guide
Rubella immunity (Rubella IgG)
Also known as: Rubella antibody test, German measles immunity
What is Rubella IgG
Rubella IgG measures the protective antibody response to the rubella virus, usually from MMR vaccination. It is most commonly requested when planning a pregnancy, because rubella infection in the first 16 weeks of pregnancy can cause congenital rubella syndrome with serious effects on the developing baby.
This biomarker entry is being clinically reviewed by our team. The factual content draws on UK guidance (NICE, NHS, Royal Colleges and the relevant speciality society where cited).
Reference range
Reported in IU/mL. Final reports always carry the issuing laboratory's range, which is what your clinician will interpret against.
| Group | Range | Note |
|---|---|---|
| Non-immune (negative or equivocal) | less than 10 IU/mL | MMR vaccination usually offered (not during pregnancy) |
| Immune (positive) | 10 IU/mL or higher | Protective immunity, no further action needed |
What it is
Rubella IgG is a specific antibody made by the immune system in response to past rubella infection or, far more commonly in the UK, after MMR vaccination. A positive IgG indicates immunity and ongoing protection against rubella. It is distinct from rubella IgM, which indicates current or very recent infection and is not part of routine immunity testing.
Why a clinician would order it
Rubella IgG is most often requested in pre-pregnancy planning so that any non-immune patient can be offered MMR vaccination before conception (the live vaccine is not given in pregnancy). It is also tested in healthcare workers, after exposure to a suspected case, and as part of antenatal serology in some settings.
If your level is outside the range
Symptoms of low Rubella IgG
- No symptoms; the implication is lack of protection against rubella if exposed in pregnancy.
What low can indicate. No previous immunity to rubella, either from never being vaccinated or from waning immunity over decades. In a non-pregnant patient, MMR vaccination is offered and immunity is rechecked in 4 to 6 weeks. In a pregnant patient, MMR cannot be given during pregnancy and is deferred until immediately after delivery.
Symptoms of high Rubella IgG
- A positive result is reassuring and carries no symptoms.
What high can indicate. Past rubella infection (rare in the UK MMR era) or successful response to MMR vaccination. The patient is protected for any future exposure including any pregnancy.
Testing tips
No fasting required. If you have recently been given MMR, wait 4 to 6 weeks before testing for immunity to allow IgG to develop. This test does not diagnose current rubella infection: rubella IgM is the test for active infection and is requested separately if clinically indicated.
Sources
UK guidance our clinicians use when interpreting this marker.
This page is general patient information, not personal medical advice. A GMC-registered clinician will review your results and tailor any interpretation to you. See our Editorial Policy for how we write and review content.
Common questions about Rubella IgG
What is a normal Rubella IgG range?
Non-immune (negative or equivocal): less than 10 IU/mL (MMR vaccination usually offered (not during pregnancy)). Immune (positive): 10 IU/mL or higher (Protective immunity, no further action needed). Always interpret your own results against the laboratory range printed on your report, since assay-specific reference ranges vary.
What does a low Rubella IgG result mean?
No previous immunity to rubella, either from never being vaccinated or from waning immunity over decades. In a non-pregnant patient, MMR vaccination is offered and immunity is rechecked in 4 to 6 weeks. In a pregnant patient, MMR cannot be given during pregnancy and is deferred until immediately after delivery.
What does a high Rubella IgG result mean?
Past rubella infection (rare in the UK MMR era) or successful response to MMR vaccination. The patient is protected for any future exposure including any pregnancy.
Do I need to fast or prepare for the Rubella IgG blood test?
No fasting required. If you have recently been given MMR, wait 4 to 6 weeks before testing for immunity to allow IgG to develop. This test does not diagnose current rubella infection: rubella IgM is the test for active infection and is requested separately if clinically indicated.
Can I order a Rubella IgG blood test privately in London?
Yes. WMG Health offers Rubella IgG as part of bespoke panels and several pre-built panels at our 134 Harley Street clinic. Results are clinician-reviewed by a GMC-registered doctor within 4 hours for the most common assays. Bespoke panels from £180; bookings via /contact/ or 020 3239 3378.