Haemophilus influenzae type b disease in Auckland children during the Hib vaccination era: 1995-2009

Abstract

Aim: To characterise Haemophilus influenzae type b (Hib) invasive disease in the era of Hib vaccination, in children of the greater Auckland region of New Zealand.

Method: Identification of sterile site culture positive Hib via the Auckland hospital laboratories databases and national laboratory surveillance database in the time period; 1995 to 2009.

Results: There were a total of 26 cases in the Auckland Region. Over the 15-year period, the annual incidence of invasive Hib disease was 0.61 per 100,000 (95% CI: 0.4-0.9) for children aged under 15 years and 1.65 per 100,000 (95% CI: 1.1-2.5) for children aged under 5 years. Ninety-two percent were under 5 years and 54% were under 1 year. Sixty percent of the children were of Maori and Pacific ethnicity. The predominant diagnosis was meningitis, accounting for 15 cases (60%). There were no fatalities. Forty-eight percent of affected children were completely unimmunised with the Hib vaccine which has been fully funded on the National Immunisation Schedule since 1994.

Conclusion: Since the introduction of the Hib vaccine, the disease rates have greatly reduced in the Auckland region. Although ethnic disparities have improved amongst the cases that occur, immunisation rates in cases are low and infants remain most at risk. Current emphasis on intensifying immunisation programmes to achieve higher vaccination rates and timeliness of delivery will help in efforts to achieve elimination of the disease in New Zealand.