H1N1 profile emerges
Aug 26, 2009
PARIS - MORE than half the fatalities from swine flu have been among young
adults, according to one of the first surveys to gather mortality data from
across the globe for the new A(H1N1) virus.
The analysis of 574 pandemic deaths from 28 countries through mid-July,
released this week, also found that being diabetic or obese significantly
boosted the risk of dying.
Neither children nor the elderly are as vulnerable as initial reports
indicated, found the study, published by Eurosurveillance, the monitoring
arm of the European Centre for Disease Prevention and Control.
'Most deaths (51 per cent) occurred in the age group of 20-to-49 year-olds,
but there is considerable variation depending on country or continent,' the
researchers reported.
Only 12 per cent of those who died were 60 or older.
All of these features - high mortality among young adults and the obese, but
not the very young or elderly - are sharply different than for the seasonal
flu.
More than 90 per cent of deaths from seasonal flu - which claims 250,000 to
500,000 lives annually according to the WHO - are in people over 65.
By contrast, with the pandemic H1N1, 'the elderly seem to be protected from
infection to some extent, perhaps due to previous exposure to similar
strains,' the study conjectured.
Persons born before 1957, other studies have suggested, were almost
certainly exposed to the milder seasonal A(H1N1) viruses that evolved from
the terrible pandemic of 1918, which left some 40 million dead.
With the 2009 strain, 'when infection does occur, however, the percentage
of deaths in elderly cases seems to be higher that in others.' One common
target across both pandemic and season strains is pregnant women, according
to the study, led by Philippe Barboza of the French Institute for Public
Health Surveillance.
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FATALITY RATIO
On Tuesday, the European Union said pregnant women should have priority in
the distribution of vaccines, along with health workers and people with
underlying health problems.
The data underlying the study also suggests that about six people die for
every 1,000 infections, two or three times the rate of seasonal flu, but far
less than the deadly pandemic of 1918.
The researchers caution, however, that it is far too early to calculate the
'case-fatality ratio' (CFR) with much accuracy.
'Evaluating CFR during a pandemic is a hazardous exercise. Aside from the
issue of whether or not a death has been caused by the influenza infection,
cases tend to be detected initially among severely ill patients with a
higher probability of dying,' they conclude.
This leads to an over estimation of how lethal a virus is, they note.
Swine flu first erupted in Mexico in April, and has since swept across the
globe, infecting hundreds of thousands and leaving more than 1,800 dead,
according to the World Health Organisation. -- AFP
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