The essentials

Rubella, or German measles, is a viral infection that is usually mild: a pink rash for a few days, a low fever and swollen glands behind the ears. Its real danger is in early pregnancy, when the virus can reach the baby and cause congenital rubella syndrome. A rubella IgG blood test shows whether you are immune, and the MMR vaccine prevents the disease.

What is rubella, at a glance?

  • Other names: German measles or three-day measles[2]. Despite the name, it is caused by a different virus from measles (rubeola).
  • How common: reported cases fell by 97% worldwide between 2000 and 2022, to 17,865 cases in 78 countries, but about 100,000 babies are still born with congenital rubella syndrome each year[1]. The United States eliminated endemic rubella in 2004; the rare cases since then are mostly linked to travel[9].
  • Who it affects: mostly children and young adults who are not vaccinated[1].
  • Key tests: rubella IgG (immunity), rubella IgM and a throat or nose swab (current infection)[2][5].

What are the symptoms of rubella?

Symptoms usually appear 2 to 3 weeks after exposure[1], and 25 to 50% of infected people have none at all[3]. In children the illness is usually mild[1]:

  • Rash: pink-red spots that start on the face and neck, then move down the body. It appears in 50 to 80% of cases and lasts 1 to 3 days[1].
  • Swollen glands behind the ears and in the neck: the most typical sign[1].
  • Low fever (under 39°C, 102.2°F), mild pink eye and sometimes nausea[1]. See our page on conjunctivitis.
  • In teenagers and adults: fever, headache, tiredness and a runny nose can come before the rash[2]. Adults, more often women, can have painful or swollen joints for 3 to 10 days[1].

Rare complications include a low platelet count with bruising (purpura) and inflammation of the brain (encephalitis)[3]. After an infection, immunity usually lasts for life[2].

Rubella or measles: how can you tell the difference?

Both cause a rash that starts on the face, so only a test can confirm rubella[6]. Rubella is usually milder: low fever, a short rash and swollen glands behind the ears. Measles usually brings a high fever, cough and red eyes for several days before the rash, and is more often serious; read our measles symptoms guide. Other rashes that can look similar include scarlet fever and chickenpox.

When should I see a doctor about rubella?

When to see a doctor

  • Emergency: call 911 for a severe headache with a stiff neck, confusion, a seizure or unusual drowsiness during or after rubella (possible encephalitis), or for heavy bleeding[2][3].
  • Within 24 to 48 hours if you are pregnant and develop a rash with fever, or have been near someone with rubella and are not sure you are immune: the date of exposure matters for testing[5]. Also for unexplained bruising, an earache or vision problems[2]. Call ahead so the clinic can protect other patients.
  • At your next appointment if you plan a pregnancy and do not know whether you are vaccinated, or if a rubella IgG result says "not immune" or "equivocal"[2].

How does rubella spread, and who is at risk?

The virus spreads through the air when an infected person coughs or sneezes, and through close contact[1]. A person is contagious from about 1 week before the rash until 1 to 2 weeks after it fades[2], most of all in the first 1 to 5 days of the rash[1].

  • Common Never vaccinated and never infected: children and adults without the MMR vaccine[2].
  • Common Living in or travelling to a country where rubella still circulates; vaccine coverage was estimated at 73% worldwide in early 2025[1].
  • Possible Close contact with a baby born with congenital rubella, who can shed the virus for a year or more[1].
  • Rare Vaccinated adults whose protection has faded[2].

How is rubella diagnosed? Reading IgG and IgM

Two different questions are answered by two different tests:

  • Am I protected? Rubella IgG. A level of 10 IU/mL or more is the usual threshold for immunity[7]. An equivocal result is treated as not immune[6]. Our page on the IgG blood test explains this antibody class.
  • Do I have rubella now? Rubella IgM, plus a throat or nose swab for the virus (PCR or culture)[2][6]. IgM can still be negative in the first days of the rash, so a second sample may be needed[6]. A clear rise of IgG between two samples also confirms a recent infection. See our page on the IgM blood test.

A fictitious report from a first prenatal visit:

Fictitious example of a rubella antibody report (United States format)
TestResultReference rangeFlag
Rubella IgG antibody6.8 IU/mLNot immune: <5.0; equivocal: 5.0-9.9; immune: ≥10.0EQ
Rubella IgM antibodyNegativeNegative
  1. Units and cut-offs: IU/mL is the international unit; each laboratory prints its own limits, and only those on your report apply.
  2. IgG 6.8, equivocal: counted as not immune. The MMR vaccine is offered after the birth, because it is not given during pregnancy[5][6].
  3. IgM negative: no sign of a current infection. IgM is only tested when an exposure or symptoms suggest rubella[5].
  4. Not on this report: an IgG of 10 IU/mL or more would mean "immune"[7].

Rubella IgG next to the other prenatal tests, each with its own units and limits? BloodSense explains every line of your complete report in plain words and helps you prepare the questions for your next visit.

Explain my rubella test results

A positive IgM is often a false alarm. Where rubella is rare, IgM can be positive without a recent infection. In a French national laboratory, only 46 of 4,104 pregnant women referred for a positive IgM or a rising IgG had a confirmed rubella infection; the others were excluded with more tests such as IgG avidity[8]. The words used on reports are explained in our guide to reactive and nonreactive results.

What does rubella mean in pregnancy?

When a woman is infected early in pregnancy, the virus reaches the baby in up to 90% of cases[1]. The risk depends on timing. In a study of more than 1,000 confirmed maternal infections[4]:

Risk to the baby after rubella with a rash, by week of pregnancy
Week of pregnancyBaby infectedDefects in infected babies
First 12 weeksMore than 80%All babies infected before 11 weeks[4]
13 to 16 weeks54% at 13-14 weeks35% (deafness alone)[4]
After 16 weeks25% by the end of the second trimester, more in the last monthNone found in 63 children[4]

Rubella early in pregnancy can also cause miscarriage or stillbirth[1]. Congenital rubella syndrome typically combines cataracts, hearing loss and heart defects, sometimes with jaundice, purpura, an enlarged liver and spleen, or a small head[3]. Before vaccination, up to 4 in every 1,000 babies were born with it[1].

Rubella IgG is checked at the first prenatal visit when there is no proof of immunity[5], often alongside the other tests of a TORCH panel in pregnancy. The same antibodies are read differently for cytomegalovirus and toxoplasmosis.

What follow-up is needed, and how often?

  • Pregnant and not immune: tell your team at once about any rash or contact with rubella; IgG and IgM are then tested, sometimes twice a few weeks apart[5][6].
  • Confirmed infection in pregnancy: a specialist discusses the risk for the baby according to the week of pregnancy[4].
  • Babies with suspected congenital rubella: tested for rubella IgM and the virus, then followed for hearing, eyes, heart and development[3]. They are kept apart from people who are not immune while they shed the virus[1].
  • After vaccination: a new IgG test is not needed to prove protection; a documented vaccine counts as evidence of immunity[6].

How is rubella treated?

There is no antiviral treatment for rubella[2]. Rest, fluids and acetaminophen for fever or joint pain are usually enough; no doses are given here, ask your pharmacist or doctor. Stay away from school, work and pregnant women for 7 days after the rash appears[6]. The problems caused by congenital rubella syndrome (hearing, eyes, heart) are treated by specialists[2].

How can rubella be prevented? The MMR vaccine in brief

  • The rubella vaccine is a live weakened virus, usually combined with measles and mumps (MMR). A single dose gives more than 95% of people long-lasting immunity[1].
  • It is part of the routine childhood schedule; ask your doctor which doses you or your child still need[2][5].
  • Planning a pregnancy: check your immunity first. If you are vaccinated, avoid becoming pregnant for 4 weeks (28 days)[2][6]. A premarital or preconception blood test often includes rubella IgG.
  • The vaccine is not given during pregnancy or to people with a severely weakened immune system[2]. When it was given by mistake in pregnancy, no problems were detected in the babies[2].
  • Side effects are usually mild: a sore arm, low fever, rash or aches[1].

Questions to ask your doctor

  1. Does my rubella IgG result mean I am immune, and what cut-off does this laboratory use?
  2. My result is equivocal or not immune: when should I get the MMR vaccine, before or after this pregnancy?
  3. I was in contact with someone who has a rash: do I need IgG and IgM now, and again later?
  4. My IgM is positive: is an IgG avidity test or a reference laboratory needed before any decision?

Frequently asked questions

Can you get rubella twice?

It is unusual: after a natural infection, immunity usually lasts for life[2]. Reinfections have been reported, sometimes in vaccinated people with low antibody levels, but they are rare[7].

My vaccination record says MMR, but my IgG is low. Am I protected?

Documented vaccination is accepted as evidence of immunity, and protection is not judged on one low result alone[6][7]. Before or after a pregnancy, your doctor may still offer another dose.

Is it safe to breastfeed after the MMR vaccine?

Yes. Breastfeeding is not a reason to delay the vaccine after the birth[5].

Should I check my rubella immunity if I am not pregnant yet?

Yes, if you may become pregnant: the blood test is recommended for all women who may become pregnant, and a woman who is not immune can be vaccinated beforehand[2].

  1. World Health Organization. Rubella: fact sheet. who.int (accessed November 11, 2026)
  2. MedlinePlus Medical Encyclopedia. Rubella. Reviewed January 1, 2025. US National Library of Medicine. medlineplus.gov (accessed November 11, 2026)
  3. Winter AK, Moss WJ. Rubella. Lancet. 2022;399(10332):1336-1346. doi:10.1016/S0140-6736(21)02691-X (accessed November 11, 2026)
  4. Miller E, Cradock-Watson JE, Pollock TM. Consequences of confirmed maternal rubella at successive stages of pregnancy. Lancet. 1982;2(8302):781-784. doi:10.1016/S0140-6736(82)92677-0 (accessed November 11, 2026)
  5. McLean HQ, Fiebelkorn AP, Temte JL, Wallace GS. Prevention of measles, rubella, congenital rubella syndrome, and mumps, 2013: summary recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2013;62(RR-04):1-34. cdc.gov (accessed November 11, 2026)
  6. Centers for Disease Control and Prevention. Epidemiology and Prevention of Vaccine-Preventable Diseases (Pink Book): rubella. cdc.gov (accessed November 11, 2026)
  7. Skendzel LP. Rubella immunity: defining the level of protective antibody. Am J Clin Pathol. 1996;106(2):170-174. doi:10.1093/ajcp/106.2.170 (accessed November 11, 2026)
  8. Bouthry E, Perillaud-Dubois C, Lebraud P, Soutière MP, Grangeot-Keros L, Vauloup-Fellous C. Positive predictive value of seroconversion or positive rubella IgM in diagnosis of maternal rubella infection: seven-years review of French National Reference Laboratory for Rubella. J Clin Virol. 2021;134:104708. doi:10.1016/j.jcv.2020.104708 (accessed November 11, 2026)
  9. Papania MJ, Wallace GS, Rota PA, et al. Elimination of endemic measles, rubella, and congenital rubella syndrome from the Western hemisphere: the US experience. JAMA Pediatr. 2014;168(2):148-155. doi:10.1001/jamapediatrics.2013.4342 (accessed November 11, 2026)
  10. MedlinePlus Medical Encyclopedia. Antibody titer blood test. Reviewed January 20, 2026. US National Library of Medicine. medlineplus.gov (accessed November 11, 2026)

This page is general information. It does not replace the advice of a doctor, who interprets your results with your symptoms, vaccination record, pregnancy stage and examination.