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Evaluating measles, mumps, rubella vaccine (live) in lactating women to enhance infant mucosal immunity

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study examines protection against Measles (as well as the related mumps and rubella viruses) by giving a booster dose of the live vaccine M-M-RvaxPro to mothers while they are nursing. The vaccine contains weakened viruses that trigger the body’s defense system without causing illness, and it is given as an injection into the muscle.

The purpose is to find out whether a booster given during lactation increases the amount of protective antibodies in breastmilk over three months compared with mothers who do not receive the vaccine. Mothers receive a single injection and then provide breastmilk samples about five times during the three‑month period. Antibodies are proteins that recognize and help neutralize germs, and the humoral immune response refers to this antibody‑based protection. The study also checks the activity of immune cells in the milk.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline visit

    On the first day after joining the study, a baseline visit is scheduled at the clinic.

    During this visit, personal health information is recorded and a sample of breastmilk is collected before any vaccination is given.

  2. Step 2

    Vaccination

    The mmr vaccine is administered as a single intramuscular injection.

    The dose is 0.5 ml of a suspension for injection, delivered into a muscle of the arm.

    The vaccine contains live attenuated (weakened) viruses for measles, mumps and rubella; these strains are unable to cause disease in healthy individuals.

  3. Step 3

    Post‑vaccination breastmilk collection

    Within a few hours after the injection, a second breastmilk sample is collected to establish the immediate effect of the vaccine.

  4. Step 4

    Scheduled follow‑up collections

    Over the next three months, breastmilk samples are collected five times in total, including the baseline and post‑vaccination collections.

    The additional collections occur at approximately two weeks, four weeks, eight weeks and twelve weeks after vaccination.

    Each collection follows the same simple procedure: the mother expresses a small amount of breastmilk, which is then handed to study staff.

  5. Step 5

    Final visit

    At the end of the three‑month period, a final visit is held to collect the last breastmilk sample and to complete any study questionnaires.

    The data from all five samples are used to measure the level of antibodies against measles in the breastmilk.

Who can join the trial?

3 criteria

  • Age: You must be between 18 and 45 years old and be in good overall health.
  • Breastfeeding plan: You need to intend to breastfeed your baby for at least two months after the study starts. (Breastfeeding means feeding your baby with your own milk.)
  • Consent ability: You must be able to understand the study and give your own permission to take part. (Consent means agreeing to join after you understand what will happen.)

Who cannot join the trial?

11 criteria

  • Unable to understand what the study involves and what will be required from you
  • Blood hemorrhage greater than 500 mL during delivery (losing more than about half a liter of blood when giving birth)
  • Acute infection at the time of delivery or in the last 7 days of pregnancy (a sudden infection when you give birth or within a week before)
  • Grade III/IV anaemia (very low level of red blood cells, which can make you feel very tired or weak)
  • Long‑lasting infections such as HBV (hepatitis B), HCV (hepatitis C), or HIV infection, or a sudden infection called toxoplasmosis (caused by a tiny parasite)
  • Current or recent use of immunosuppressive drugs (medicines that lower the activity of your immune system)
  • Active neoplasia (having cancer that is currently growing)
  • Carrying twins or triplets (having two or three babies at the same time)
  • Infants born before 35 weeks of pregnancy (baby arrives early; full term is about 40 weeks)
  • Infant birthweight below 2.5 kg (baby weighs less than about 5.5 pounds)
  • Infant with serious congenital abnormalities or a congenital infection (major birth defects or infections present at birth)
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Investigated drugs

M-M-RvaxPro is a combined measles, mumps, and rubella (MMR) vaccine that contains live, weakened viruses. It is given as a small injection into the muscle. In this study the vaccine is administered to breastfeeding mothers to see if it increases the level of protective antibodies in their breastmilk, which could help protect their infants from these infections. The vaccine works by gently “teaching” the mother's immune system to recognize the viruses, so the mother makes antibodies that can be passed to the baby through milk.

What is already known about the treatment

Measles, mumps and rubella vaccine (live attenuated) - The vaccine is given as a 0.5 ml intramuscular injection of a liquid suspension that is mixed from a powder and solvent shortly before use. It is an approved, widely used vaccine that has been on the market for many years and is well described in medical literature. The vaccine is used to protect people, especially children, from measles, mumps and rubella infections. It works by introducing weakened (live‑attenuated) viruses that stimulate the body’s immune system to produce antibodies, giving lasting protection, and it belongs to the class of live viral vaccines.

Investigated diseases

Measles - Measles is a contagious viral infection that spreads through inhalation of airborne droplets. After an incubation period of about 10‑14 days, a fever, cough, runny nose, and red eyes appear, followed by tiny white spots inside the mouth. A red, blotchy rash then develops, beginning on the face and spreading downward over several days. The rash fades gradually as the fever subsides, and the illness usually resolves within two weeks.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-524862-12-00Estimated enrolment120 patientsSponsorUniversite Libre de Bruxelles

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