Estimating the Haemophilus influenzae type b (Hib) disease burden and the impact of Hib vaccine in Fiji.
OBJECTIVE
To estimate Haemophilus influenzae type b (Hib) disease burden in Fiji in children under the age of 5 years (under-5s) prior to vaccine introduction. To compare estimates from WHO's Hib rapid assessment tool (RAT), with that from decline in disease after vaccine introduction.


METHODS
Laboratory data (meningitis), hospitalization and mortality data (pneumonia and meningitis) before and after Hib vaccine introduction were collected. The RAT protocol provides two independent estimates of pre-vaccine disease burden (one based on meningitis incidence laboratory data and the other based on mortality statistics). A third estimate uses the decline in disease following vaccine introduction.


RESULTS
The decline in meningitis hospitalizations implies a pre-vaccine Hib meningitis incidence of 66 per 100,000 in under-5s. This compares with a pre-vaccine RAT estimate of Hib meningitis incidence of 84 per 100,000 (for 1992-1993). The RAT estimated the total annual pre-vaccine Hib burden (meningitis plus pneumonia) at 476 cases and 36 deaths per year ("meningitis incidence method") and 70 cases and 5 deaths ("child mortality method"). Hib vaccine led to declines of 32% (95% confidence interval (CI)=11-48%), and 78% (95% CI=22-94%) for all under-5s meningitis hospitalizations and deaths, respectively. There was no similar consistent decline in pneumonia hospitalizations or deaths after vaccine introduction, except for a statistically significant reduction in pneumonia mortality in children aged under 1 year.


CONCLUSIONS
Hib disease constitutes an important burden on the health of Pacific children that can be rapidly reduced with Hib vaccine. In this setting, routine morbidity statistics (comparing pre-and post-vaccine) provided an estimate of Hib meningitis burden which is broadly similar to that of the Hib RAT, suggesting that both might be valid ways to estimate Hib meningitis incidence. However, Hib pneumonia burden could not be estimated from routine statistics.
Wilson
Nick
N
367a Karori Road, Karori, Wellington, New Zealand. nwilson@actrix.gen.nz
Mansoor
Osman
O
Wenger
Jay
J
Martin
Rebecca
R
Zanardi
Lynn
L
O'Leary
Michael
M
Rabukawaqa
Vilikesa
V
D000818:Animals; D001428:Bacterial Vaccines / Q000627:therapeutic use*; D005367:Fiji / Q000453:epidemiology; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000276:immunology* / Q000401:mortality; D019741:Haemophilus influenzae type b / Q000276:immunology*; D006736:Horses / Q000276:immunology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008583:Meningitis, Haemophilus / Q000453:epidemiology* / Q000276:immunology* / Q000401:mortality
D001428:Bacterial Vaccines