Reduction of meningitis and impact on under-5 pneumonia after introducing the Hib vaccine in the Kingdom of Tonga.

AIMS: To document the impact of Hib vaccine on Haemophilus influenzae (Hi) invasive disease, meningitis and inpatient pneumonia in children under 5 in the Kingdom of Tonga. METHODS: Cases of meningitis and pneumonia were sourced from the paediatric discharge book from 1 January 2000 to 2 November 2007 and from computerised discharge records from Vaoila Hospital on the island of Tongatapu where approximately 70% of the total population resides. Laboratory-confirmed cases were sourced from the microbiology laboratory register over the same period. RESULTS: Prior to the introduction of Hib vaccine in 2005, there were, on average, 5.6 cases of invasive Hi disease per year. In the 22 months after Hib vaccine introduction, there was only one case of invasive Hi disease. This corresponds to a fall in the annual incidence of invasive Hib disease from 54.3 to 5.1/100,000 children under 5 years of age. The annual incidence of inpatient pneumonia has fallen by 28.3% from 1007.6 to 722.8/100,000 children under 5 in the 22 months after introducing the vaccine. CONCLUSION: Hib vaccine has reduced invasive Hi disease and Hi meningitis in Tonga. The reduction in inpatient pneumonia is more likely a reflection of annual fluctuations in viral pneumonia than of a reduction in Hib pneumonia, but ongoing surveillance is recommended.

High incidence of Haemophilus influenzae type b infection in children in Pacific island countries.

The Haemophilus influenzae type b (Hib) disease burden among children <5 years old in 4 Pacific island countries (PICs) was estimated. The incidence of confirmed Hib meningitis was calculated using the numbers of culture-confirmed isolates. In addition, the World Health Organization (WHO) Hib Rapid Assessment Tool (RAT) was used to estimate the true Hib meningitis incidence and the number of Hib meningitis and pneumonia cases, as well as the number of deaths due to Hib meningitis and pneumonia. The Hib meningitis annual incidence in 3 PICs was 70-84 cases per 100,000 children <5 years old. For PICs, the RAT is likely to overestimate the Hib pneumonia burden, as it assumes a 5 : 1 ratio of Hib pneumonia to Hib meningitis. The true ratio is likely to be 1 : 1. The high Hib disease burden and the relative cost-effectiveness of Hib vaccine make the introduction of Hib vaccine a good investment for PICs, costing US1000 dollars-US10,000 dollars for each death prevented--a number that ignores savings from reductions in the cost of treatment.

Haemophilus influenzae type b infection in children in Pacific countries.

The Haemophilus influenzae type b (Hib) disease burden among children under five years in four Pacific island countries (PIC was estimated. The incidence of confirmed Hib meningitis was calculated using numbers of culture confirmed isolates. In addition, the WHO Hib Rapid Assessment Tool (RAT) was used to estimate the true Hib meningitis incidence and the number of Hib meningitis and pneumonia cases and deaths. The Hib meningitis annual incidence in three PICs was 70 to 84 per 100,000 children under five years. The high Hib disease burden and the relative cost-effectiveness of Hib vaccine, make the introduction of Hib vaccine a good investment for PICs costing US$ 1,000-10,000 for each death prevented - ignoring treatment cost savings.