THURSDAY, Sept. 29 (HealthDay News) -- The United States was hard hit by the 2009 pandemic influenza A (H1N1) virus, and Utah experienced a particularly high proportion of severe illness compared with previous influenza seasons, particularly among certain subsets of the population, according to research published in the Sept. 30 issue of the U.S. Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.
Rachelle Boulton, M.S.P.H., of the Utah County Health Department in Provo, and colleagues compared hospitalization data from three previous influenza seasons to the 2009 H1N1 season to assess the impact of H1N1 and then use that information to stratify those most at risk for serious illness.
The researchers found the 2009 H1N1 season resulted in far more hospitalizations than previous flu seasons -- 1,327 compared with a previous average of 435. Severe illness and mortality were also more prevalent, occurring in about 25 percent of hospitalized cases compared with 14 percent of those hospitalized in previous seasons. Racial/ethnic minorities, pregnant women, and residents of Salt Lake County were disproportionally affected, and the "spring wave" appeared to have a heavier impact than the "fall wave."
"Surveillance for influenza hospitalizations can provide essential data to public health authorities that will help them identify those populations at greatest risk for severe illness," the authors write.