title: Ethnic disparities in acquiring 2009 pandemic H1N1 influenza: a case-control study.
abstract: BACKGROUND
  Novel risk factors were associated with the 2009 pandemic A/H1N1 virus (pH1N1). Ethnicity was among these risk factors. Ethnic disparities in hospitalization and death due to pH1N1 were noted. The purpose of this study is to determine whether there are ethnic disparities in acquiring the 2009 pandemic H1N1.
  
  
  METHODS
  We conducted a test-negative case-control study of the risk of pH1N1 infection using data from Ontario, Canada. Cases were laboratory confirmed to have influenza using reverse-transcriptase polymerase chain reaction (RT-PCR), and controls were obtained from the same population and were RT-PCR negative. Multivariate logistic regression was used to determine the association between ethnicity and pH1N1 infection, while adjusting for demographic, clinical and ecological covariates.
  
  
  RESULTS
  Adult cases were more likely than controls to be self-classified as East/Southeast Asian (OR = 2.59, 95% CI 1.02-6.57), South Asian (OR = 6.22, 95% CI 2.01-19.24) and Black (OR = 9.72, 95% CI 2.29-41.27). Pediatric cases were more likely to be self-identified as Black (OR = 6.43, 95% CI 1.83-22.59). However, pediatric cases without risk factors for severe influenza infection were more likely to be South Asian (OR 2.92, 95% CI 1.11-7.68), Black (OR 16.02, 95% CI 2.85-89.92), and West Asian/Arab, Latin American or Multi-racial groups (OR 3.09 95% CI 1.06-9.00).
  
  
  CONCLUSIONS
  pH1N1 cases were more likely to come from certain ethnic groups compared to test-negative controls. Insights into whether these disparities arise due to social or biological factors are needed in order to understand what approaches can be taken to reduce the burden of a future influenza pandemic.
authors.forename: Debeka
authors.initials: D
authors.lastname: Navaranjan
authors.affiliation: Department of Public Health Sciences, Public Health Ontario, 480 University Avenue, Suite 300, Toronto, Ontario M5G 1 V2, Canada. laura.rosella@oahpp.ca.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rosella
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Kwong
authors.forename: Michael
authors.initials: M
authors.lastname: Campitelli
authors.forename: Natasha
authors.initials: N
authors.lastname: Crowcroft
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018912:Arabs / Q000208:ethnology; D002170:Canada / Q000453:epidemiology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005006:Ethnicity; D005260:Female; D054625:Healthcare Disparities; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D012307:Risk Factors; D055815:Young Adult