*Fri 04 Sep 2009 14:57*

**Assessing H1N1 risk **

What sort of risk does H1N1
(Swine Flu) present this flu season? To assess this, it might be
helpful to estimate some H1N1 risks and then compare it to risks with
which we are more familiar.

So let's look at some numbers. The worldwide case fatality rate of H1N1 (the number of people who have died of H1N1, divided by the number of people who have gotten H1N1) has been estimated to be 0.45%. Unlike seasonal flu, roughly 80% of those who have died of H1N1 are less than 65 years old (typically 90% of seasonal flu fatalities are 65 years old or over). If we assume a 15% probability of getting H1N1 this flu season, the likelihood of someone under the age of 65 dying of H1N1 this season is thus 0.15 x 0.0045 x 0.80, i.e 0.054% or 1 in 1852. This is a little less than the one-year general odds of death due to external causes in the US, approximately 1 in 1681.