- Measles (M)
- Illness: high fever, cough, conjunctivitis, coryza, rash
- Complications: encephalitis, corneal ulcer/scar
- Mumps (M)
- Illness: mild illness with gland swelling and headache
- Complications: orchitis (and infertility), unilateral deafness, encephalitis, meningitis
- Rubella (R)
- Illness: flu-like illness with rash
- Complication in pregnant women: congenital rubella syndrome
NB: A paper, published in 1998, linked the MMR vaccine to autism. This research has since been discredited and the author has been struck off the medical register for serious misconduct. Further detailed studies have shown there is no link between the MMR vaccine and autism.