Outbreak of 2009 Pandemic Influenza A (H1N1) at a New York City School

Once introduced into a high school in New York City, the 2009 H1N1 virus spread quickly among students and staff, with an influenza-like illness developing in more than 800 people during a 2-week period. In this population, which had no previous exposure to this virus, the incubation period was estimated to be about 2 days, the median generation time 2.7 days, and the within-school reproduction number 3.3. Once introduced into a high school in New York City, the 2009 H1N1 virus spread quickly among students and staff, with an influenza-like illness developing in more than 800 people during a 2-week period in April 2009. In April 2009, clusters of cases of 2009 H1N1 influenza involving potential human-to-human transmission were reported in multiple countries. 1 One of the earliest and largest clusters identified in the United States was an acute outbreak of 2009 H1N1 influenza at a New York City high school. 2 This outbreak prompted an immediate and rapid investigation by the New York City Department of Health and Mental Hygiene. This report describes the clinical and epidemiologic findings from this investigation. On Thursday, April 23, 2009, a nurse from a high school in Queens, New York, that had an enrollment of 2686 students notified the . . .