MMR at 6 Months Trial

Inclusion Criteria: * Gestational age of 32+ weeks. * Birth weight of 1000+ grams. * Signed informed consent from the parents. Exclusion Criteria: * Immune-deficiency (primary or acquired) or -suppression. * Intake of immune modulating medicine (including high doses of corticosteroids) (M-M-RVAXPRO is not contraindicated in individuals who are receiving topical or low-dose parenteral corticosteroids, e.g. for asthma prophylaxis or replacement therapy). * Signs of severe illness or major malformation. * No Danish-speaking parent. * Children with a history of anaphylactic, anaphylactoid, or other immediate reactions (e.g., hives, swelling of the mouth and throat, difficulty breathing, hypotension, or shock) subsequent to egg ingestion are excluded. * Children with known fructose intolerance, thrombocytopenia or any coagulation disorder will be excluded. * Children who received blood or plasma transfusions, or administration of human immune serum globulin within the last 3 months will be excluded. * Further, children are excluded from the trial if any contraindication is suspected: history of hypersensitivity to any measles, mumps, or rubella vaccine, or to any of the excipients, including neomycin. * Children with active untreated tuberculosis, blood dyscrasias, leukaemia, lymphomas of any type, or other malignant neoplasms affecting the haematopoietic and lymphatic systems will be excluded.