Deaths in '09 swine flu pandemic 10 times higher than thought

Date: Nov-28-2013A new study by over 60 researchers from 26 countries suggests that the number of people

who died in the 2009 global H1N1 "swine flu" outbreak is much higher than official figures

show.

Writing in PLOS Medicine, they estimate the total respiratory deaths worldwide to be up

to 203,000, some 10 times higher than the World Health Organization (WHO) official total,

which is based on lab-confirmed cases.

When they added deaths by other causes exacerbated by H1N1, the figure was nearly double this

amount, or over 20 times higher than the WHO lab-confirmed cases.

Commenting on the WHO-funded study, lead author Lone Simonsen, a research professor in the

Department of Global Health at the George Washington University School of Public Health and Health

Services in the US, says:

"We also found that the mortality burden of this pandemic fell most heavily on younger people

and those living in certain parts of the Americas."

Based only on lab-confirmed cases, the WHO official figures report that just under 18,500 people

died in the 2009 flu pandemic.

This total was already considered to be much lower than actual numbers because not all cases are

lab-confirmed in a flu outbreak.

The new study's findings are important because they help us to consider whether the

public health response to the outbreak was excessive or not. Based on the official figures, some

might suggest it was, but based on these new estimates, that may no longer be the case.

Although nowhere near as devastating as the 1918 Spanish flu, which killed tens of millions of

people, a death count in the hundreds of thousands still represents a formidable foe.

Study used respiratory deaths data from 21 countries

For the study, the team used weekly virology data kept by the WHO and information on actual

deaths directly from 21 countries, representing aprroximately 35% of the world's population.

From this, they could estimate numbers of respiratory deaths in those countries (H1N1 causes

respiratory death when it gets into the lungs and causes pneumonia).

They used the estimates from the 21 countries with a new statistical method to arrive at a global figure, yielding a global death count of 203,000 respiratory deaths due to the 2009 H1N1

outbreak.

However, when they took into account the fact that H1N1 can also cause deaths by making

existing conditions - such as heart disease - worse, the team discovered the 2009 death toll

could be as high as 400,000.

The researchers also estimate that between 62-85% of deaths in the 2009 H1N1 swine flu

pandemic were among people under 65 years of age - in marked contrast to seasonal flu epidemics

where the highest proportion of deaths occurs mainly among seniors.

Regional variations differ from previous estimate

In terms of individual countries, there were also some stark contrasts. For instance in the

Americas, countries including Mexico, Argentina and Brazil suffered a swine flu casualty rate some 20

times higher than other countries - the highest respiratory death rates in the world.

Parts of Europe, plus Australia and New Zealand, in contrast, had much lower rates of

deaths.

The regional variation that this study suggests is quite different from the 2009 pattern of swine flu deaths reported by the US

Centers for Disease Control and Prevention (CDC) in 2012.

The CDC estimated that the death count was very heavy in Africa and Southeast Asia and lower

in the Americas and Europe.

The researchers in this new study could not find figures to substantiate the CDC estimates in

Africa and Southeast Asia, but Prof. Simonsen says it is not easy to investigate these regions

because there is insufficient data to make reliable estimates of what really happened.

She calls for further studies to look more closely at how the virus spread in the poorer

nations. Plus, she says it is important to continue studying the pandemic to find out why some countries

suffered much worse than others.

Written by Catharine Paddock PhD

Copyright: Medical News Today

Not to be reproduced without the permission of Medical News Today.

Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.