Severe H1N1 Swine Flu symptoms progression and risk factors

The World Health Organization (WHO) hosted a meeting at the Pan American Health Organization in Washington DC on October 14th thru the 16th to compare the findings and experiences by clinicians, scientists and public health officials from the Americas, Europe, Asia, Africa, the Middle East and Oceania. The results of their findings were released October 19th.
Progression of Severe H1N1 Swine Flu Symptoms
This meeting confirmed that the overwhelming majority of people who contract the H1N1 virus still experience uncomplicated, often even mild, flu-like symptoms and recover without need of medical treatment within a week.
It was widely agreed that the progression of severe H1N1 swine flu symptoms when they do occur is vastly different than those presented during normal seasonal flu. In addition to those with pre-existing medical conditions, swine flu is striking previously healthy patients unexpectedly hard. Severe symptoms tend to display about 3 to 5 days after the onset of flu-like symptoms. The primary display of severe swine flu symptoms is acute respiratory issues, including progressive viral pneumonia, and secondary infections leading to bacterial pneumonia. Many required immediate ventilatory support.
Risk Factors for Severe H1N1 Swine Flu Symptoms
Also widely agreed upon were the three groups at highest risk for developing severe symptoms of swine flu. Those groups include pregnant women, especially in the third trimester, children younger than 2 years of age, and people with chronic lung or respiratory conditions, including asthma.  
A large portion of those affected also suffered from obesity, though what role, if any, obesity has as a risk factor for severe H1N1 swine flu symptoms is unclear at best.