During the past year important studies on the incidence and aetiology
of acute respiratory infections have been published emphasizing the hi
gh incidence and diverse aetiology in children. Probabilities of diagn
osing these infections are increasing, especially with the use of the
polymerase chain reaction, which can, for example, be used for diagnos
is of pertussis. Several vaccines against respiratory pathogens, notab
ly pertussis, pneumococci, non-typeable Haemophilus influenzae, respir
atory syncytial virus, influenza and parainfluenza have entered, or ar
e close to entering, safety and immunogenicity studies in children.