About the Test
Purpose of the test
The purpose of a rubella test is to detect a rubella infection or assess immunity to the virus. Testing may be ordered for diagnosis, prenatal screening, or to find evidence of immunity.
Rubella testing is used to diagnose or rule out this condition in patients with symptoms that are suggestive of rubella.
The rubella virus can be spread through coughing and sneezing as well as prolonged close contact with an infected person. While rubella is generally a mild illness that goes away without treatment, it can have harmful effects if transmitted to a developing fetus during pregnancy.
Rubella testing is routinely ordered as part of a prenatal panel, which is a group of tests used to find infections and other problems early in pregnancy. As part of this panel, rubella testing is used to check the pregnant person for immunity to rubella.
People who are pregnant and become infected with rubella can transmit the infection to their fetus. The risk of transmission is greatest during the first trimester and in the last few weeks of pregnancy. Complications from a rubella infection during pregnancy can include miscarriage, stillbirth, and birth defects.
Proof of immunity
In addition to prenatal testing, there are several circumstances in which doctors may order rubella testing to assess a person’s immunity to the virus. Some health care professionals, students, and international travelers may need to provide proof of immunity for work, school, or travel.
Immunity to rubella develops after MMR vaccination, which protects against future infection and prevents the spread of the virus to others. In people who have not been vaccinated, immunity develops after recovery from a past infection.
In some instances, people may become infected even if they have been vaccinated or have had rubella before.
What does the test measure?
Rubella testing looks for evidence of exposure to the rubella virus. Different tests are available that look for antibodies to the rubella virus or genetic material from the virus.
Rubella antibody tests measure the amount of rubella antibodies in a blood sample to help diagnose a current or recent rubella infection. After contracting a rubella infection, the body develops antibodies to the virus. Antibodies are proteins made by the body’s immune system to fight infections, viruses, and bateria.
This type of testing is also used to see if people have previously been vaccinated against rubella. A rubella antibody test checks for the level of antibodies, also known as antibody titers, to the rubella virus that may indicate current or recent infection or past vaccination. There are several types of rubella antibody tests:
- Immunoglobulin M (IgM) antibody test IgM antibody testing is typically the first test used to diagnose rubella. People who are newly infected with rubella develop IgM antibodies to the virus. Most people will develop IgM antibodies as soon as four days after the onset of symptoms. IgM antibody levels can remain detectable for six to eight weeks or longer after infection.
- Immunoglobulin G (IgG) antibody test: Another type of antibody test that may be used to diagnose rubella and establish immunity is IgG antibody testing. IgG testing may be performed to help distinguish between recent infections and immunity due to past infection. IgG testing is also the preferred method for checking immunity to rubella in people who are pregnant.
Nucleic acid amplification testing (NAAT) identifies genetic material, called RNA, of the rubella virus in a nasal swab, throat swab, or a urine sample. Rubella NAAT is much less common compared to antibody testing but may be used in specific situations. There are different types of NAAT. The type of NAAT used for rubella testing is referred to as reverse transcription polymerase chain reaction (RT-PCR) test.
When should I get a rubella test?
Rubella testing may be ordered if you have symptoms of rubella and have recently traveled internationally or were exposed to someone with symptoms similar to rubella. Most people with rubella develop a rash that begins on the face before spreading to other parts of the body. Other symptoms may include:
- Sore throat
- Joint stiffness or pain
- Conjunctivitis, also called pink eye
If you are pregnant, your doctor will check for rubella immunity as part of your initial prenatal assessment. Rubella testing can show whether you’ve been vaccinated or have immunity due to a past rubella infection.
If you are traveling internationally or if you are required to do so for work or school, you may need to be tested for rubella to provide proof of immunity.
Finding a Rubella Test
How to get tested
Rubella testing is ordered by a health professional. The sample required for testing is taken in a doctor’s office or other medical setting such as a laboratory or hospital.
Can I take the test at home?
At-home testing kits for rubella are not commercially available in the United States. Rubella testing must be ordered by a health professional and the sample obtained at a medical office, laboratory or hospital.
How much does the test cost?
The cost of testing for rubella can differ based on several factors including health insurance status, where the test is being performed, and whether other testing is being ordered at the same time.
Your health care provider or insurance company can discuss the cost of testing if you have questions. They can speak with you about out-of-pocket costs like co-pays and deductibles.
Taking a Rubella Test
The sample needed for your rubella test will vary depending on the type of testing that has been ordered. Testing may require a sample of blood, urine, or a nasal or throat swab.
Before the test
No special test preparation is required before taking a rubella test.
As with any laboratory test, it is important to speak with your health care provider before testing and carefully follow any pre-test instructions.
During the test
During a blood draw, a needle is inserted into a vein in your arm to withdraw the blood sample needed for testing. An elastic band, called a tourniquet, is typically placed around the upper part of the arm to increase blood flow to the vein being used for the procedure. The area where the needle will be inserted is cleaned with an antiseptic. A needle with a small test tube or vial attached is inserted into the arm to start the flow of blood. There may be a mild sting or pain when the needle is inserted but it should not last long.
During a rubella test that requires a nose or throat swab, a cotton swab is inserted into both nostrils or the throat. The swab is typically left in place for a few moments and then turned a few times to ensure collection of an adequate sample for testing. There may be some discomfort while the swab is inserted. Your eyes may water or you may gag or flinch. The procedure lasts a few moments and does not cause lasting discomfort.
If your health care provider is requesting a urine sample for rubella testing, you will be asked to provide a sample in a cup for laboratory analysis.
After the test
After a blood draw is complete, pressure and a bandage will be placed over the area to stop any bleeding and to prevent bruising.
Post-test care is generally not required for patients providing a nasal or throat swab or a urine sample.
All collection methods are routine medical procedures and there should be no long-term side effects. Typically, you can return to your normal activities. However, if you are being tested because of symptoms that suggest rubella, it is important to speak with your health care provider about precautions you should take to prevent the spread of rubella to other people.
Rubella Test Results
Receiving test results
The results of your rubella test are typically available within a few days. Your test results may be uploaded to an online health portal or sent to you through the mail. Your doctor may also contact you directly to speak with you about the results of your test.
Interpreting test results
Your test report will include information about the type of rubella test performed as well as your test results. Test results may include reference ranges as well as the laboratory’s interpretation of test results. Reference ranges describe the expected range of antibody levels used to interpret test results.
The following sections include information about the interpretation of rubella antibody tests and rubella NAAT testing.
Rubella antibody tests (IgG/IgM)
The results of rubella antibody testing may be reported as follows:
- Detected, positive, or immune: Sufficient antibodies are present in the sample to indicate current infection, prior infection, or vaccination and subsequent immunity.
- Indeterminate or equivocal: Some antibodies are present in the sample, which may indicate current infection, prior infection or vaccination. Repeat testing may be recommended.
- Undetected, negative, or non-immune: Very few or no antibodies were present in the sample, which does not indicate current infection, prior infection, or immunity due to vaccination.
If you have questions about your antibody test and what the results mean for your health, it is important to speak with your health care provider.
Rubella nucleic acid amplification testing (NAAT)
The results of rubella NAAT testing may be reported in the following manner:
- Detected or positive: Rubella RNA was detected in the sample, which may indicate a current infection.
- Indeterminate or inconclusive: There was not enough information for interpretation.
- Undetected or negative: Rubella RNA was not detected in the sample, which may indicate no current infection. Confirmation with antibody testing may be suggested.
Your doctor can provide more information about NAAT to detect rubella and what your test results mean in the context of your health.
Are test results accurate?
The results of rubella testing are generally considered accurate, though no test is perfect. There are a few factors that can impact the reliability of the test results:
The timing of testing can affect the accuracy of your test results. Ruella tests ordered for diagnosing symptoms should be performed within a certain period of time following the onset of a rash or fever that suggests rubella infection.
- Rubella antibody tests: Antibody testing should be ordered five days after the start of a rash if possible. Testing before that could lead to a false negative test result, which is when a person tests negative but has a rubella infection. If rubella testing is ordered within three days of the start of the rash, another rubella test should be ordered in two to four weeks to confirm a diagnosis.
- Rubella NAAT: Testing should be performed as soon as possible after the start of symptoms. Ideally, sample collection should happen one to three days after symptoms develop, but no later than seven days after the start of a fever and rash.
False positive test results can also occur because some antibodies, other than those developed in response to a rubella infection, can affect the results of IgM and IgG blood tests. A false positive result is when a person who is not infected with rubella tests positive for the infection.
For example, rheumatoid factor and antibodies to other viruses can cause a false positive test result for rubella. If a health care provider is concerned about false positive test results, NAAT may be used to confirm a diagnosis or immunity.
Do I need follow-up tests?
Typically, no follow-up testing is necessary after a test to check for rubella immunity or diagnose rubella infection in adults. However, repeat testing may be recommended if there are questions about an initial test result. Your doctor is in the best position to speak with you about any follow-up testing or care that may be necessary.
If you are pregnant and have been diagnosed with rubella, your health care provider may order further testing to determine if the infection has been transmitted to the fetus.
Questions for your doctor about test results
You may have questions about your rubella test report as you review the results with your health care provider. The following questions may be helpful to ask:
- Which rubella test did I receive?
- What was the result of my test?
- Will I need to take another rubella test?
- If I have rubella, what are the next steps for my health care?
- If I am pregnant and am not showing immunity to rubella, what steps can I take to protect myself and the health of my baby?
- Do I need to be vaccinated against rubella?
Rubella testing in infants
Rubella can be transmitted to a fetus if the person who is pregnant becomes infected during pregnancy. Congenital rubella syndrome (CRS) is a group of birth defects caused by the transmission of rubella to a fetus and can lead to hearing loss, heart disease, and cataracts.
To confirm a diagnosis of rubella in an infant, testing is conducted after birth and before the age of one. Testing may include rubella antibody tests and rubella NAAT.
If your infant’s health care provider is concerned about rubella infection, they can provide more information about the evaluation of your infant and the testing that may be needed to confirm a diagnosis.