Mumps’ main symptom is swelling of the parotid salivary glands on one or both sides of the face, just below and to the front of the ears.24

Possible complications are glandular fever and tonsillitis, and more seriously, viral encephalitis. Pancreatitis and hearing loss (permanent in 1 in 20,000 cases) are also possible. If the disease develops in someone who has gone through puberty, it can cause inflammation of the testes (with a 1 in 10 chance of reduced sperm count in men) or the ovaries.21,48

Respiratory syncytial virus (RSV) infections are very common, with most children likely to have one bout before reaching 2 years old. Usually causing cold symptoms and fever, RSV increases the risk of bronchiolitis or pneumonia in babies under 6 months old or young children who were born prematurely, and sepsis.25,27