Two studies, which are available online as early release articles and will be published in the November edition of the Journal of the American Medical Association (JAMA), detail the characteristics, treatment and outcomes of critically ill patients with H1N1 in Mexico and Canada [1-2].
Although the death rate in each of the studies is quite different, it nonetheless is as high or higher than that of seasonal flu. Furthermore, although seasonal flu typically affects people of older age — the average annual rate of influenza-associated hospitalizations over the last 20 years for people age 65 and older is 70% [3] — these studies show that H1N1 is striking many who are much younger. In both studies, the majority of critically ill patients with influenza A H1N1 had rapidly progressive respiratory failure and required mechanical ventilation.