Serologically Confirmed Household Transmission of 2009 Pandemic Influenza A (H1N1) Virus During the First Pandemic Wave--New York City, April-May 2009

Background. Understanding transmissibility of influenza viruses within households is critical for guiding public health response to pandemics. We studied serologically confirmed infection and disease among household contacts of index case patients with 2009 pandemic influenza A (H1N1) virus (pH1N1) infection in a setting of minimal community pH1N1 transmission. Methods. We defined index case patients as students and staff of a New York City high...