Laboratory-confirmed pandemic h1n1 influenza in hospitalized adults: findings from the Canadian Nosocomial Infections Surveillance Program, 2009-2010.

Surveillance for pandemic H1N1 influenza was conducted between June 1, 2009, and May 31, 2010, among adults at 40 participating hospitals in the Canadian Nosocomial Infection Surveillance Program. The first wave was characterized by a higher proportion of Aboriginals and pregnant women as well as severe outcomes, compared to the second wave.