H1N1 : Description

During an epidemic such as the influenza A(H1N1) crisis that occurred in Montréal in 2009, low-income populations are likely to be more affected than the general population.  The greater vulnerability of low-income groups is associated in part with preexisting health conditions such as chronic diseases, and with adverse environmental conditions. Possible explanations include the following: 1) greater exposure to the virus; 2) weaker immune response to the virus; and 3) reduced access to care and influenza vaccination; or 4) suboptimal adherence to recommended preventive measures and treatment.

According to the ethical principles set out in the 2006 Canadian Pandemic Influenza Plan, during a pandemic, public health authorities must make plans to implement, in a timely fashion, effective interventions likely to reach all populations. The geographical locations of low-income populations in Montréal are fairly well-known. Nevertheless, more in-depth analysis of evidence-based data on the evolution of social inequalities in health (SIH) over time within the context of the influenza A(H1N1) pandemic would enhance understanding of public health initiatives from the perspective of reducing SIH.


  1. Compare experiences during the influenza A(H1N1) pandemic—disease incidence and morbidity—of low-income populations with those of the general population.

  2. Compare vaccine coverage and use of flu clinics, by level of deprivation.

  3. Assess the impact of strategies favoured in public health (priority given to vaccination of groups at risk, use of large vaccination centres and of influenza-like illness speciality clinics) pertaining to the reduction of SIH.


The study uses a mixed research methodology. A qualitative phase traces the chronology of the milestones marking the two waves of the A(H1N1) pandemic internationally and in Canada, Québec and Montréal; it also tracks the chronology of public health interventions implemented in Montréal. A quantitative phase involves a secondary analysis of data from Relevé quotidien de la situation à l’urgence et au centre hospitalier (RQSUCH), as well as from five population surveys, the 2006 census and the vaccination registry. This phase documents influenza activity over time by level of deprivation and examines the differential response to public health initiatives set up to contain the epidemic.


Meetings with public health decision-makers will be set up to discuss the study findings and formulate recommendations. Findings are expected to better guide future public health initiatives aimed at reducing SIH. Findings will be disseminated through a research report and scientific articles.


This research project is funded by Canadian Institutes of Health Research.