H1N1 (swine flu) vs the seasonal flu

H1N1 globally, according to the WHO the swine flu global death toll tops 5,700:

• in the Americas – 4,175 deaths have been reported since the first appearance of the disease in April.
• Southeast Asia – 605 deaths
• West Pacific – 465
• Europe – 281
• East Mediterranean – 111
  
• Africa – 75
  

H1N1 vaccine development has stirred the controversy surrounding inoculations. The Atlantic questions the impact of a swine flu vaccine, while Newsweek tries to tackle the inoculation misinformation.

And Effect Measure explains the epidemiology of a pandemic flu (eg H1N1) versus a seasonal flu:

…the main feature [is] not the clinical characteristics or the virulence of the virus. So far this looks pretty much like a standard influenza A virus — except for the epidemiology.

Epidemiology is the public health science that studies the patterns of illness in populations. One kind of pattern we study is who is getting sick. And it is a change in this pattern that is one of the big differences between a pandemic strain and a seasonal strain. Pandemic strains have a greater tendency to infect and make sicker much younger victims. In seasonal influenza it is the over 65 age group that contributes most of the serious illness and deaths, but with pandemic strains (not just the current one), lack of immunity in the population makes those under age 65 a bigger target and they sicken and die proportionately more than in a non-pandemic season. And that’s exactly what we are seeing this year.