patients suspected of having influenza and requiring hospital assessment were tested with real - time reverse transcription pcr by using protocols from the us centers for disease control and prevention ( 2 ) . this analysis included only persons ( case - patients ) with confirmed pandemic ( h1n1 ) 2009 who were admitted to public hospital beds in the nz wellington and hutt valley regions . the results of viral testing were not available at the time of admission and therefore did not affect decisions about admission . sex , age , clinical service , inpatient mortality , and self - reported ethnicity were available , as was limited information about medical conditions . ethnicity data were aggregated as nz european , maori , pacific islanders , or other ( i.e. , all other and unspecified ethnicities combined ) . admission rates per 100,000 persons were calculated using regional denominator data from the 2006 nz census ( 3 ) and age standardized by a direct method using 10-year age groups . testing for pandemic ( h1n1 ) 2009 began on april 24 , 2009 , and local community transmission was detected in the wellington region early in june . during june 8august 31 , pandemic ( h1n1 ) 2009 was identified in 229 hospitalized case - patients . hospitalizations began in june , peaked in july , and then declined rapidly ( figure 1 ) . the mean age of admitted persons was 26 years ( range 082 years ) ; 62% were < 30 years of age . a total of 117 ( 51% ) admissions were under adult medical services , 79 ( 34% ) , under pediatric medical services , and 15 ( 7% ) , under obstetric services . mean duration of admission was 6.1 days ( range 024 days ) and 111 ( 48% ) patients stayed in hospital for < 72 hours ( figure 2 ) . nineteen ( 8% ) case - patients were admitted to intensive care or high dependency units for at least 1 night . five ( 2% ) case - patients died during their hospital stay ; all of these deaths were attributed to pandemic ( h1n1 ) 2009 . number of hospitalizations for pandemic ( h1n1 ) 2009 , by date of admission , wellington region , new zealand , june duration of hospitalization for case - patients with pandemic ( h1n1 ) 2009 , wellington region , new zealand , june  august 2009 . seventy - four ( 32% ) case - patients were nz european , 70 ( 31% ) were maori , 64 ( 28% ) were pacific islanders , 17 ( 7% ) were other , and 4 ( 2% ) were unspecified . the rate of admission for nz europeans in the wellington region was 25.6 per 100,000 . age - adjusted rates for pacific islanders and maori were 180 and 128 per 100,000 , respectively . ninety - one ( 40% ) of the total group had a chronic lung condition ; of these , 58 ( 64% ) had asthma . for 116 ( 51% ) , rates of chronic respiratory conditions were lower for pacific islanders than for maori or all others ( 28% , 41% , and 48% , respectively ) ( table ) . ethnicity and presence of a chronic respiratory condition were dependent (  = 6.22 , 2 df , p = 0.044 ) . rates of other medical conditions for pacific islanders , maori , and all others were 56% , 41% , and 54% ( independent  = 3.67 , 2 df , p = 0.16 ) . the wellington region had higher population - adjusted hospitalization rates for pandemic ( h1n1 ) 2009 than did new zealand and countries overseas ( 4 ) . in australia , the reported rate of hospitalizations was one third that in our region ( 5 ) . local testing or referral patterns may have contributed to more admissions in a variety of ways . first , our rates of laboratory confirmation may be higher because of ready access to timely pcr results ( 6 ) , facilitating investigation and case detection in persons admitted to a hospital . although both countries have free access to hospital care for pandemic ( h1n1 ) 2009 , nz hospitals are always busy in the winter , so clinical services attempt to manage patients in the community wherever possible . our study shows that pacific islanders and maori were 7 and 5 times more likely , respectively , than nz europeans to require hospital admission . these findings are consistent with observations from previous influenza epidemics . during the 1918 pandemic , the death rate was 7-fold higher in maori than in the nz europeans ( 7 ) . in samoa in 1918 , 80% of the population was considered infected , and 7,264 died from a total population of 36,405 ( 8) . other indigenous communities , such as aboriginals in australia and inuit in canada , also appear to have higher rates of severe influenza - related illness ( 9 ) . a higher incidence of pandemic ( h1n1 ) 2009 in pacific islanders or maori households is likely to have led to greater representation across the spectrum of clinical manifestations , including severe disease ( environmental science and research , unpub . this explanation is supported by national surveillance , which demonstrated higher rates of confirmed pandemic ( h1n1 ) 2009 in maori and pacific islanders . however , this finding depends heavily on community testing , which was never uniformly available across nz and ceased to be offered routinely once nz switched to a manage - it phase ( 10 ) . an alternative cause of higher rates in pacific islanders or maori may be a greater readiness to self - refer to an emergency department for assessment when unwell . this study does not address why severe influenza is more frequently observed in pacific islanders and maori . we did not observe higher rates of preexisting medical conditions in the hospitalized maori and pacific islanders and noted lower rates of chronic respiratory conditions in pacific islanders . however , other conditions were detected only on discharge summary review and not by screening or systematic questioning ; thus other undocumented conditions may contribute to ethnic disparity in hospitalizations . a comparison of seropositivity rates in representative sections of high- and low - risk communities is needed to ascertain whether high hospitalization rates resulted from high rates of community transmission , preexisting conditions , or higher rates of complications of influenza . future control strategies , including primary prevention or improved access to timely treatment , could then be refined to the needs of maori and pacific islanders . in any case , targeting vaccination to the elderly and persons with known comorbid conditions will fail to protect a substantial minority of persons who need hospital care and will particularly disadvantage pacific islanders . the observed age distribution is consistent with other reports describing acute pandemic ( h1n1 ) 2009 ( 11 ) . most admissions were for only a few days , but a substantial minority of hospitalized case - patients required care for several weeks . pandemic ( h1n1 ) 2009 has resulted in hospital admissions and severe illness in our study population more frequently than reported elsewhere . what proportion is due to good access to nucleic acid - based testing , local disease transmission dynamics , or intrinsic susceptibility of our population to the virus is not clear . nonetheless , our findings will interest those planning health services internationally , including other areas serving pacific islanders and indigenous communities .
community transmission of influenza a pandemic ( h1n1 ) 2009 was followed by high rates of hospital admissions in the wellington region of new zealand , particularly among maori and pacific islanders . 
 these findings may help health authorities anticipate the effects of pandemic ( h1n1 ) 2009 in other communities .