Ontario's 36 public health units, the provincial ministry of health and federal public health agency completed a web survey in 2010 to identify surveillance systems used routinely and during the pandemic and to describe the perceived utility of systems for monitoring pandemic activity and informing decision making. Follow-up semi-structured interviews were conducted with key informants to elucidate drivers for specific public health actions taken during the pandemic and, specifically, to understand the role syndromic data played in influencing decisions among those who had access.