Research finds flu is a major killer in New Zealand with Maori, Pasifika and low-income earners most vulnerable

June 9, 2017

New research from the University of Otago, Wellington, shows that influenza kills about 500 New Zealanders each year, and the risk of premature death is much higher for Māori, Pasifika, men and those living in relative poverty.

The research published this week in the Journal of Infection, is based on work by Dr Trang Khieu as part of her PhD at the University of Otago, Wellington.

"Our research shows that is probably New Zealand's biggest single infectious disease killer, accounting for about 1.8 per cent of total deaths in NZ," says Dr Khieu.

This research has also, for the first time in any country, estimated the distribution of flu deaths in relation to ethnicity and social deprivation (as well as gender and age group which have been looked at in previous studies).

The study was based on a 15 year period (from 1994 to 2008) prior to the last influenza pandemic (2009-2010). This kind of modelling needs multiple years of data to produce good estimates of flu deaths, partly because the severity of the varies so much from year to year.

"Future work will update these estimates for the post-pandemic period, but we would expect the findings to be broadly similar," says Dr Khieu.

The study showed that the inequalities in influenza deaths are striking:

  • In the key 65-79 year age group, Māori are 3.6 times more likely to die of influenza than those of European/other ethnicity. And Pacific People are 2.4 times more likely to die compared with European/others during a typical flu season.
  • Those living in the most deprived 20 per cent of neighbourhoods are almost twice (1.8 times) as likely to die of influenza compared with those living in the least deprived areas.
  • Men are also more vulnerable, with males aged 65-79 years almost two times (1.9 times) more likely to die of influenza than females.

"These results show that it is important to target flu vaccination and other interventions to the most vulnerable groups, in particular Māori and Pacific people and men aged 65-79 years and those living in the most deprived areas," says study co-author Professor Michael Baker, from the University of Otago, Wellington.

"Having an annual influenza vaccination is still the best protection we have. It is also free of charge for everyone 65 years and over," Professor Baker says.

The study used modelling (a series of quasi Poisson regression models) to estimate influenza deaths in each population group. This approach is necessary because only a small proportion (about one in 23 in New Zealand) of influenza deaths is recognised, confirmed and recorded on certificates. This modelling shows that the largest numbers of (37 per cent) are circulatory conditions such as heart attacks and strokes. In most instances, flu will not even be suspected as the cause, particularly in cases of sudden death.

The crude influenza mortality rate found in this study was 13.5 per 100,000 for all causes. This rate is similar to those estimated for other high income countries, though none have reported the distribution of influenza mortality risk by ethnicity and socioeconomic position.

All of these studies show that increasing age is the single most important risk factor for influenza mortality. In New Zealand, 86 per cent of deaths occurred in those 65 years of age and over, a rate of 90.3 per 100,000.

"This research illustrates how the borderline between infectious diseases and non-communicable diseases, such as heart disease and cancer, is not particularly firm. Infectious diseases like influenza can precipitate sometimes fatal events such as heart attacks, and chronic conditions such as cardiovascular disease make us more vulnerable to infections," says Professor Baker.

Explore further: Influenza estimated to kill about 400 New Zealanders each year

More information: Trang Q.T. Khieu et al. Modelled seasonal influenza mortality shows marked differences in risk by age, sex, ethnicity and socioeconomic position in New Zealand, Journal of Infection (2017). DOI: 10.1016/j.jinf.2017.05.017

Related Stories

Influenza estimated to kill about 400 New Zealanders each year

November 24, 2014
New Zealand has an average of 401 influenza-associated deaths each year according to estimates published for the first time. This is an average annual mortality rate of 10.6 per 100,000 population.

Alternative flu vaccine should reduce medical costs and save lives

January 25, 2017
A study just published in Human Vaccines & Immunotherapeutics suggests that an alternative vaccine might bring clinical benefits and cost savings if used on a large scale when compared to the one currently in widest use.

In a bad flu season, high-dose flu vaccine appeared better at preventing deaths in seniors

March 2, 2017
The high-dose flu vaccine appeared to be more effective at preventing post-influenza deaths among older adults than the standard-dose vaccine, at least during a more severe flu season, according to a large new study of Medicare ...

Flu surveillance suggests an early and severe season

June 1, 2015
Today is the first day of winter, and for many Australians with winter comes influenza.

Patients with flu-associated pneumonia less likely to have received flu vaccine

October 5, 2015
Among children and adults hospitalized with community-acquired pneumonia, those with influenza-associated pneumonia, compared with those with pneumonia not associated with influenza, had lower odds of having received an influenza ...

CDC: Flu activity still up in U.S. in fourth week of 2013

February 4, 2013
(HealthDay)—In the fourth week of 2013, influenza activity remained elevated in the United States, with the proportion of pneumonia and influenza-linked deaths above the epidemic threshold, according to FluView, a weekly ...

Recommended for you

Two Group A Streptococcus genes linked to 'flesh-eating' bacterial infections

September 22, 2017
Group A Streptococcus bacteria cause a variety of illnesses that range from mild nuisances like strep throat to life-threatening conditions including pneumonia, toxic shock syndrome and the flesh-eating disease formally known ...

Ecosystem approach makes urinary tract infection more treatable

September 22, 2017
The biological term 'ecosystem' is not usually associated with urinary tract infections, but this should change according to Wageningen scientists.

Residents: Frontline defenders against antibiotic resistance?

September 22, 2017
Antibiotic resistance continues to grow around the world, with sometimes disastrous results. Some strains of bacteria no longer respond to any currently available antibiotic, making death by infections that were once easily ...

Individualized diets for irritable bowel syndrome better than placebo

September 21, 2017
Patients with irritable bowel syndrome who follow individualized diets based on food sensitivity testing experience fewer symptoms, say Yale researchers. Their study is among the first to provide scientific evidence for this ...

Superbug's spread to Vietnam threatens malaria control

September 21, 2017
A highly drug resistant malaria 'superbug' from western Cambodia is now present in southern Vietnam, leading to alarming failure rates for dihydroartemisinin (DHA)-piperaquine—Vietnam's national first-line malaria treatment, ...

Investigators may unlock mystery of how staph cells dodge the body's immune system

September 21, 2017
For years, medical investigators have tried and failed to develop vaccines for a type of staph bacteria associated with the deadly superbug MRSA. But a new study by Cedars-Sinai investigators shows how staph cells evade the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.