Volume 18, Number 1—January 2012
Historical Review
Differential Mortality Rates by Ethnicity in 3 Influenza Pandemics Over a Century, New Zealand
Nick Wilson
, Lucy Telfar Barnard, Jennifer A. Summers, G. Dennis Shanks, and Michael G. Baker
, Lucy Telfar Barnard, Jennifer A. Summers, G. Dennis Shanks, and Michael G. BakerTable
Comparison of mortality rates for Māori versus non-Māori/European residents of New Zealand during multiple influenza pandemics*
| Pandemic and data source | Mortality rate |
Comments (see Methods for details) | ||
|---|---|---|---|---|
| Māori | Non-Māori | Ratio† | ||
| 1890s pandemic | ||||
| 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). |
| 1918–19 pandemic | ||||
| 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. |
| 1957 pandemic | ||||
| 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. |
| 2009 pandemic¶ | ||||
| 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.
