For a seven year period clinical and epidemiological data were prospectively collected on children aged <10 years with microbiologically confirmed invasive Haemophilus influenzae type b infection in the Oxford region to study the epidemiology of the disease and determine the potential impact of early primary immunisation in infints. Computer records of primary immunisations given to these cases were retrospectively analysed and, where necessary, hospital and general practitioner records were searched to determine the immunisation history.

earlier, around 1941. A similar birth cohort effect is seen in incidence.8 There is little evidence for this particular effect in our study perhaps because Scottish women are less at risk than their English and Welsh contemporaries or perhaps because the risk can be largely negated by an effective screening programme. Women reaching the age of 50 may welcome release from the cervical screening programme as they embark on the breast screening programme. It is not known whether the increasing uptake of hormone replacement therapy will maintain the higher incidence of cervical intraepithelial neoplasia seen in younger women by rejuvenating the cervix and a prospective randomised trial would be warranted. We thank Dr K A Hussein in the cytopathology laboratory, Dundee Royal Infirmary, Margaret Bell in gynaecological cancer registry, Ninewells Hospital, Wilma Paterson in the Maryfield Computer Centre, and their colleagues for their close cooperation at all times.