Admission to hospital for pneumonia and influenza attributable to 2009 pandemic A/H1N1 Influenza in First Nations communities in three provinces of Canada

Background: Early reports of the 2009 A/H1N1 influenza pandemic (pH1N1) indicated that a disproportionate burden of illness fell on First Nations reserve communities. In addition, the impact of the pandemic on different communities may have been influenced by differing provincial policies. We compared hospitalization rates for pneumonia and influenza (P&I) attributable to pH1N1 influenza between residents of First Nations reserve communities and the general population in three Canadian provinces. Methods: Hospital admissions were geocoded using administrative claims data from three Canadian provincial data centres to identify residents of First Nations communities. Hospitalizations for P&I during both waves of pH1N1 were compared to the same time periods for the four previous years to establish pH1N1-attributable rates. Results: Residents of First Nations communities were more likely than other residents to have a pH1N1-attributable P&I hospitalization (rate ratio [RR] 2.8-9.1). Hospitalization rates for P&I were also elevated during the baseline period (RR 1.5-2.1) compared to the general population. There was an average increase of 45% over the baseline in P&I admissions for First Nations in all 3 provinces. In contrast, admissions overall increased by approximately 10% or less in British Columbia and Manitoba and by 33% in Ontario. Subgroup analysis showed no additional risk for remote or isolated First Nations compared to other First Nations communities in Ontario or Manitoba, with similar rates noted in Manitoba and a reduction in P&I admissions during the pandemic period in remote and isolated First Nations communities in Ontario. Conclusions: We found an increased risk for pH1N1-related hospital admissions for First Nations communities in all 3 provinces. Interprovincial differences may be partly explained by differences in age structure and socioeconomic status. We were unable to confirm the assumption that remote communities were at higher risk for pH1N1-associated hospitalizations. The aggressive approach to influenza control in remote and isolated First Nations communities in Ontario may have played a role in limiting the impact of pH1N1 on residents of those communities.