Shanta M. Zimmer, Corey J. Crevar, Donald M. Carter, James H. Stark, Brendan M. Giles, Richard K. Zimmerman, Stephen M. Ostroff, Bruce Y. Lee, Donald S. Burke, Ted M. Ross

In April 2009, a new pandemic strain of influenza infected thousands of persons in Mexico and the United States and spread rapidly worldwide. During the ensuing summer months, cases ebbed in the Northern Hemisphere while the Southern Hemisphere experienced a typical influenza season dominated by the novel strain. In the fall, a second wave of pandemic H1N1 swept through the United States, peaking in most parts of the country by mid October and returning to baseline levels by early December. The objective was to determine the seroprevalence of antibodies against the pandemic 2009 H1N1 influenza strain by decade of birth among Pittsburgh-area residents.