Volume 18, Number 1—January 2012
Differential Mortality Rates by Ethnicity in 3 Influenza Pandemics Over a Century, New Zealand
|Pandemic and data source||Mortality rate
||Comments (see Methods for details)|
|Individual mortality data in BDM database (10)||Unknown (deaths not registered)||9.1% increase in deaths for 1890–94 compared with 1885–89||–||Based on comparison of no. deaths for top 10 surnames (see method used for 1957 pandemic). Official data also suggest increased influenza deaths for the 1890s beginning in 1890 (17).|
|National mortality data, second wave (6), n = 8,573 deaths||4,230/100,000 population||580/100,000 population) (European)||7.3||See limitations with data quality described in the main text. Comparison was not age-standardized.|
|Mortality in New Zealand military personnel, second and third waves,‡ n = 1,113||2,501/100,000 population||1,103/100,000 population (European/ other)||2.3 (1.6–3.1)§||New Zealand military personnel of Pacific peoples ethnicity also had a raised mortality rate, but absolute number of deaths was small (n = 12) and difference was not significant.|
|National mortality data for Asian influenza pandemic, official report (11), n = 179 deaths||39.6/100,000 population||6.4 per 100,000 population (European)||6.2||Of note, at this time surveillance systems were crude, and attention to quality ethnicity coding was not robust. There was no widespread use of vaccination in response to this pandemic in New Zealand.|
|Individual mortality data in BDM database for selected surnames (10), n = 38 deaths in Aug/Sep 1957||49.0% increase for Aug/Sep 1957 compared with same period in 1956 and 1958||Whole New Zealand population: 20.3% increase||2.4 (Māori vs. total population)||See Discussion for limitations with this method.|
|All cases with pandemic (H1N1) 2009 as primary cause of death,# n = 49||2.0 (0.8–3.1)§||0.8 (0.5–1.1)§||2.6 (1.3–5.3)§||For Pacific peoples in New Zealand, rate = 4.6 (2.0–7.2)§|
*BDM, Births, Deaths & Marriages.
†Māori:non-Māori except as indicated.
‡Age standardization was not possible with available data; 1 study reported that Māori and European soldiers had similar median ages of 24 and 26 years, respectively (8).
§Values in parentheses are 95% confidence intervals.
¶Jun–Sep 2009. Cumulative age-standardized mortality rates per 100,000 population, age-standardized to Māori population. Ratio is Māori versus other New Zealanders (non-Māori and non-Pacific, mainly European).
#Identified by Mortality Review Group.