… or is obesity simply Yet Another Risk Factor in severity of this illness?

Probably the latter, but health officials seem interested in the developing data.

From CTV:

… in a report released Friday, health officials detailed the cases of 10 Michigan patients who were very sick from swine flu in late May and early June and ended up at a specialized hospital in Ann Arbor. Three of them died.

Nine of the 10 were either obese or extremely obese. Only three of the 10 had other health problems. Two of the three that died had no other health conditions.

This hardly settles the question of whether obesity is its own risk factor for swine flu. It’s possible the patients had undiagnosed heart problems or other unidentified conditions.

The report is called Intensive-Care Patients With Severe Novel Influenza A (H1N1) Virus Infection — Michigan, June 2009 and is published in MMWR, the CDC’s rapid turnaround publication for disease. The report warns:

This report describes the clinical findings of a limited series of patients with novel influenza A (H1N1) virus infection and refractory ARDS …. This patient group represents the most severely ill subset of persons with novel influenza A (H1N1) virus infection and is notable for the predominance of males, the high prevalence of obesity (especially extreme obesity), and the frequency of clinically significant pulmonary emboli and MODS. All required advanced mechanical ventilator support, reflecting severe pulmonary damage. The pulmonary compromise described in this report suggests that severe pulmonary damage occurred as a result of primary viral pneumonia. Although data are not available, this damage also might be attributable to secondary host immune responses (e.g., through cytokine dysregulation triggered by high viral replication). However, bacterial coinfection in the lung not identified by blood culture or bronchoalveolar lavage cannot be excluded.

…

The high prevalence of obesity in this case series is striking. Whether obesity is an independent risk factor for severe complications of novel influenza A (H1N1) virus infection is unknown. Obesity has not been identified previously as a risk factor for severe complications of seasonal influenza. ….

Further characterization of severe cases of novel influenza A (H1N1) virus infection in the United States and worldwide is needed to determine the frequency of the findings from this limited case-series.

You can read the report here.

Clearly this is very preliminary and I suspect that this will not develop. In other words, I suspect that existing poor health related to the cardiopulmonary system is a serious risk factor with any flu. But we shall see.