"Have I had the MMR?" is a surprisingly common question. Vaccination records go missing, people move countries, and childhood memories of chickenpox are often vague. Then a new job in a hospital, a nursery or a laboratory asks for evidence of immunity, and nobody quite knows the answer.
A vaccine immunity blood test looks for antibodies, the proteins the immune system makes after an infection or a vaccine. This article covers the immunity tests in the BPR catalogue for measles, mumps, rubella, chickenpox and hepatitis B: what each one measures, who usually asks for them, and how the sample is collected.
What an immunity test actually shows
These tests measure IgG antibodies or, for hepatitis B, surface antibodies. LML describes the measles, mumps and rubella tests as showing whether a person has been infected in the past or vaccinated. They do not tell the two apart. Either way, the presence of antibodies indicates that the immune system has met the virus or the vaccine before.
Why not simply rely on the vaccination card? A study of medical students in Spain compared documented vaccination with blood results. Written records predicted immunity well for most vaccines, but less well for measles, mumps and hepatitis B, where the positive predictive value was 90.0%, 85.9% and 67.2% respectively (Godoy et al., 2025). The authors suggest comparing documented vaccination for those three with serology results.
Measles, mumps and rubella
The Measles, Mumps, Rubella Immunity test reports three IgG results in a single blood sample: measles, mumps and rubella. If only one of the three matters to you, the BPR catalogue also lists the single tests:
- Measles Antibodies (IgG) Immunity
- Mumps Antibodies (IgG) Immunity
- Rubella Antibody (IgG) Immunity
The NHS explains that two doses of the MMR vaccine give long-term protection, and that it is especially important to be vaccinated if you could become pregnant, are travelling to a country with a higher risk of these infections, are a healthcare worker, or were born between 1970 and 1990, as people born then may not have been vaccinated against all three infections (NHS, MMR vaccine).
Rubella deserves a special mention. LML notes that rubella can cause serious problems in pregnancy and that the rubella immunity test is important for women planning a pregnancy. If immunity is absent, vaccination before pregnancy may be recommended.
A German systematic review of people working in childcare found that large proportions of younger workers were seronegative for measles, meaning their blood showed no antibodies (Kofahl et al., 2020). It is one reason employers in some sectors ask for this check.
Chickenpox (varicella zoster)
The Varicella Zoster IgG Antibodies (immunity) test looks for antibodies against the varicella zoster virus, which causes chickenpox and shingles. According to LML, a high antibody level suggests the person is likely immune, while a low level may point to a need for vaccination or further monitoring.
The NHS says that healthcare workers who are not immune to chickenpox may be recommended the vaccine if their work involves close contact with patients, and that people unsure whether they have had chickenpox may need a blood test to check (NHS, Chickenpox vaccine).
Hepatitis B
The Hepatitis B Immunity (Quantitative) test measures surface antibodies (anti-HBs). LML explains that this helps show immunity status and whether vaccination is needed. Because it is quantitative, it reports a level rather than a simple yes or no.
The NHS lists the groups for whom hepatitis B vaccination is recommended, including healthcare workers and some laboratory staff, people travelling to parts of the world with a higher risk, and close family members or sexual partners of someone with hepatitis B (NHS, Hepatitis B vaccine). Many occupational health teams ask for a level after the vaccine course.
