Oct. 12 (Bloomberg) -- Swine flu caused otherwise healthy younger people to develop severe respiratory failure, a pattern of attack not seen since the 1918 flu that killed millions of people, according to three studies published today. Severe illness from swine flu, also know as H1N1, developed rapidly in patients admitted to the hospital, especially young people, and sent previously healthy people to intensive care units, according to studies of outbreaks in Canada and Mexico published today in the Journal of the American Medical Association. A third study from Australia and New Zealand found some patients benefited from a machine that replenished blood oxygen levels in extremely ill patients.
Today’s reports are consistent with previous research that found that while H1N1 produces similar symptoms and outcomes as seasonal flu in most cases, it targets a younger population and can lead to severe illness and death. The seasonal flu kills about 36,000 people a year in the U.S., though the majority of those deaths are in people over the age of 80.
“These studies provide important signals about what clinicians and hospitals may confront in the coming months,” said Douglas White and Derek Angus, professors of critical care medicine at University of Pittsburgh School of Medicine, in Pittsburgh, in an editorial accompanying the studies. “H1N1 can produce rapidly progressive respiratory failure.”
In Canada, the average age of 168 patients studied was 32 years. Mechanical ventilation was required for 136 patients, and about 17 percent of the intensive care patients died.
About 4,500 people have died worldwide from swine flu, which is widespread in most U.S. states.
“The influenza outbreak lasted about three months” in Mexico and Canada, White and Angus wrote in the editorial. “The peak lasted just a few weeks, during which time hospitals struggled to accommodate the increased patient load.”