Ongoing surveillance of vaccine preventable diseases (VPDs)
The occurrence of a number of diseases which can be prevented by vaccination is monitored by the NCIRS.
Routine analysis of data
Every quarter, the NCIRS receives data collected by the National Notifiable Diseases Surveillance System (NNDSS), and assists with analysis and interpretation of these data.
Invasive Haemophilus influenzae type B (Hib) disease
Since Hib vaccines were included in the immunisation schedule in 1993 for children under 5 years of age, invasive Hib disease (meningitis, epiglottis etc) has become uncommon in Australia. The incidence has fallen from 500 cases per year to 33 reported cases in 1997.
Failure of Hib vaccine to provide protection is being studied through the Australian Paediatric Surveillance Unit (APSU). Data have been collected since 1998. In that year there were 14 cases of Hib disease (including 7 with meningitis, and 3 with epiglottitis) in children under 5 years of age in Australia. Seven of the 14 children had been adequately immunised for age. This vaccine failure rate is being compared with similar data from Europe and the USA.
Pneumococcal disease group: (L to R) Robin Gilmour,
Peter McIntyre, Melanie Wong and Han Wang
Invasive pneumococcal disease
Conjugated pneumococcal vaccines suitable for use in children have shown excellent results in clinical trials and have been licensed in the USA. A study of this disease in 1997-1999 has provided information about the strain of organism, the illness it causes and risk factors for children in greater Sydney. This prospective case-control study of 600 subjects aged 10-15 years showed that previous pneumonia and household exposure to tobacco smoke were risk factors for invasive pneumococcal disease. References 66 and 67.
Pneumococcal vaccination in older adults is also being studied in Victoria (since 1998 the only State
with a publicly funded pneumococcal vaccination program) and New South Wales.
Pertussis (whooping cough)
Studies analysing the impact of pertussis in Australia, the role of serology in the diagnosis of pertussis [Reference 62], and the efficacy of pertussis vaccine are in progress or near completion. The impact of the introduction of the fifth dose of pertussis vaccine and of the introduction of acellular pertussis vaccine on the incidence of disease and on immunisation coverage are being analysed. Reference 77. Vaccine efficacy is being determined using the screening method. Studies of pertussis morbidity in adults [Reference 65] and of the sensitivity and specificity of the serological diagnosis of pertussis are completed. In collaboration with workers in The Netherlands molecular analysis is being used to identify escape mutants in a series of Australian pertussis isolates, and the isolates are being serotyped.