# 3945
While it is true that 90% of the H1N1 infections have been among those under 65, when those over that age get this virus, it can provoke a very serious illness.
That’s one of the messages from a study, published today in JAMA, entitled Factors Associated With Death or Hospitalization Due to Pandemic 2009 Influenza A(H1N1) Infection in California
Reuters summarizes the study below, and you’ll find excerpts from the abstract below that.
Swine flu not just a threat to young: study
Tue Nov 3, 2009 5:22pm EST
By Julie Steenhuysen
CHICAGO (Reuters) - Swine flu can cause severe disease in people of all ages and appears to pose a special threat to those who are obese, according to an analysis of H1N1 cases in California released on Tuesday.
Public health researchers analyzed the state's first 1,088 hospitalized and fatal cases of H1N1 infection between April 23 and August 1.
Like other studies, they found the average patient who was hospitalized with H1N1 flu was younger than what is commonly seen with seasonal flu, but they also found severe disease at both ends of the age spectrum.
"What our study shows was that once you were hospitalized, if you were elderly you have a higher risk of dying," Dr. Janice Louie of the California Department of Public Health in Richmond, whose study appears in the Journal of the American Medical Association.
Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, said the study matches the CDC's own observations -- that H1N1 affects all age groups, including people over 65.
Janice K. Louie, MD, MPH; Meileen Acosta, MPH; Kathleen Winter, MPH; Cynthia Jean, MPH; Shilpa Gavali, MPH; Robert Schechter, MD, MPH; Duc Vugia, MD; Kathleen Harriman, PhD; Bela Matyas, MD; Carol A. Glaser, MD, DVM; Michael C. Samuel, DrPH; Jon Rosenberg, MD; John Talarico, DO, MPH; Douglas Hatch, MD; for the California Pandemic (H1N1) Working Group
JAMA. 2009;302(17):1896-1902.
Results During the study period there were 1088 cases of hospitalization or death due to pandemic 2009 influenza A(H1N1) infection reported in California. The median age was 27 years (range, <1-92 years) and 68% (741/1088) had risk factors for seasonal influenza complications.
Sixty-six percent (547/833) of those with chest radiographs performed had infiltrates and 31% (340/1088) required intensive care. Rapid antigen tests were falsely negative in 34% (208/618) of cases evaluated.
Secondary bacterial infection was identified in 4% (46/1088). Twenty-one percent (183/884) received no antiviral treatment. Overall fatality was 11% (118/1088) and was highest (18%-20%) in persons aged 50 years or older. The most common causes of death were viral pneumonia and acute respiratory distress syndrome.
Conclusions In the first 16 weeks of the current pandemic, the median age of hospitalized infected cases was younger than is common with seasonal influenza. Infants had the highest hospitalization rates and persons aged 50 years or older had the highest mortality rates once hospitalized. Most cases had established risk factors for complications of seasonal influenza.
