THE NEW ZEALAND MEDICAL JOURNAL Vol 115 No 1159 ISSN 1175 8716 The beneficial impact of Hib vaccine on disease rates in New Zealand children Nick Wilson, Jay Wenger, Osman Mansoor, Michael Baker and Diana Martin Abstract Aim To examine the impact of Haemophilus influenzae type b (Hib) vaccine on the burden of Haemophilus influenzae (Hi) disease in New Zealand children aged under five years (under-5s). Methods Analysis of national mortality, hospitalisation, laboratory, and notification data. Results The introduction of Hib vaccine in 1994 led to a 92% decline (95%CI = 89 – 94%) in the hospitalisation rate of Hi meningitis for under-5s (1995–2000 compared to 1988–1993). Pre-vaccine, the Hi meningitis hospitalisation rate was 27 per 100 000 in the under-5s and this declined to 2 per 100 000. Even though Hi meningitis declined in all ethnic groups (eg down to 3 per 100 000 among Maori), there was a worsening of equity with the proportion of children hospitalised with Hi meningitis who were Maori increasing from 23% to 40% of all cases. The rate of epiglottitis hospitalisations also declined substantially (by 94%, 95%CI = 89 – 96%). Conclusions Hib vaccination appears to be preventing at least 80 cases of meningitis and 30 cases of epiglottitis every year in under-5s in New Zealand. But the beneficial impact of Hib vaccination has been less for Maori and so there is a need for further improvements in immunisation coverage in those populations with the highest disease burdens. Haemophilus influenzae type b (Hib) was the most common cause of life-threatening bacterial infection (usually meningitis) in New Zealand children up until the early 1990s. 1 Maori and Pacific children were at greatest risk. 2 The substantial disease burden led to demands for using the newly-available Hib conjugate vaccine. 2,3 Hib vaccine was added to the childhood immunisation schedule in January 1994 with DTP-Hib (Tetramune) replacing DTP at six weeks, three months and five months, and monovalent Hib being given at eighteen months. Parents with children aged under five years (under-5s) were also encouraged to take them to their general practitioner for immunisations. Coverage has since probably exceeded 80% for the third dose and a decline in laboratory reported Hib invasive disease followed. 4,5 This decline has subsequently continued in recent years. 6 Hospital data for Christchurch also suggest that a decline in epiglottitis is associated with the introduction of Hib vaccine. 7 This report uses routinely collected hospital and mortality data along with surveillance data to examine in more detail the impact of the introduction of Hib immunisation on the health of New Zealand children. NZMJ 9 August 2002, Vol 115 No 1159 Page 1 of 7 http://www.nzma.org.nz/journal/ © NZMA