Clinical and Epidemiologic Characteristics of Children Hospitalized With 2009 Pandemic H1N1 Influenza A Infection

Background: In 2009, pandemic H1N1 influenza caused significant morbidity and mortality worldwide. We describe the clinical and epidemiologic characteristics of children and adolescents hospitalized for 2009 H1N1 infections in Milwaukee, Wisconsin from April 2009 to August 2009. Methods: We conducted retrospective chart reviews of hospitalized patients with laboratory-confirmed 2009 H1N1 infections. Data on financial burden associated with these infections were obtained and analyzed. Results: A total of 75 children hospitalized for 2009 pandemic H1N1 infections were identified; the median age was 5 years (range, 2 months-19.2 years); 56% were males; 56% were Non-Hispanic Blacks; and 75% had at least one underlying medical condition. Twenty-four percent had only upper respiratory symptoms. Bacterial coinfections occurred in 1.3%. All but one patient received antivirals, 80% of patients received antibacterials, 18.6% were admitted to the intensive care unit, 6% required mechanical ventilation, 2.6% required extracorporeal membrane oxygenation, and 2.6% died. The total charges incurred for H1N1 influenza hospitalizations were $4,454,191, with individual charges being highest for children >12 years of age. Conclusions: The majority of children with pandemic H1N1 influenza-associated hospitalizations had uncomplicated illness despite the frequent presence of high-risk conditions in our patient population. Laboratory-confirmed 2009 pandemic H1N1 influenza hospitalizations resulted in substantial health care and economic burden during the first wave of the pandemic in spring 2009.