Swine Influenza Investigation Team are listed in the Appendix.

In April 2009, an outbreak of novel swine-origin influenza A (2009 H1N1 influenza) occurred at a high school in Queens, New York. We describe the outbreak and char-acterize the clinical and epidemiologic aspects of this novel virus. Methods The New York City Department of Health and Mental Hygiene characterized the out-break through laboratory confirmation of the presence of the 2009 H1N1 virus in nasopharyngeal and oropharyngeal specimens and through information obtained from an online survey. Detailed information on exposure and the onset of symptoms was used to estimate the incubation period, generation time, and within-school re-productive number associated with 2009 H1N1 influenza, with the use of estab-lished techniques. Results From April 24 through May 8, infection with the 2009 H1N1 virus was confirmed in 124 high-school students and employees. In responses to the online questionnaire, more than 800 students and employees (35 % of student respondents and 10 % o