12 October 2012
Impact of H1N1 on Socially Disadvantaged Populations: Systematic Review
A systematic review was conducted by Tricco A.C et al (1) on the impact of H1N1 on socially disadvantaged populations by examining the burden of hospitalization, severe illness and mortality data associated with influenza A(H1N1)pdm09 among ethnic minorities and other disadvantaged populations. The primary focus of their investigation was to answer the question ‘what is the evidence that the burden of H1N1 associated with social disadvantage?’. The review was conducted using standardized search strategies of all related published articles and gray literature with targeted searching in low-income countries (LIC) and lower-middle-income countries (LMIC). Socially disadvantaged populations included ethnic minorities, low socioeconomic status, groups without access or disproportionate access to healthcare, and LIC or LMIC. Ethnic minorities were classified as non-predominant races as well as indigenous populations and LIC and LMIC were classified according to the World Bank’s classification of countries (2). The investigators found 62 studies that met the selection criteria, however most were conducted in high income countries (HIC) with only 12 studies conducted in LIC or LMIC. Although the initial search terms were for socially disadvantaged populations, the results are only generalizable to ethnic minorities in HIC. The investigators found that generally the prevalence of hospitalization, severe illness and mortality due to H1N1 was high for ethnic minorities in HIC. A similar risk of ICU admission and death was observed among ethnic and non-ethnic minorities.
The H1N1 pandemic was associated with a high burden of illness in terms of hospitalization, severe illness, absenteeism and cost. (1) It was also the most scrutinized influenza pandemic in history and has provided an opportunity to learn a great deal about the disease. While individuals with chronic medical conditions and pregnancy have long been widely accepted as having increased risk of severe disease, the pandemic brought to the fore two underappreciated risk groups; persons with obesity and those who are socially disadvantaged (3). Racial and ethnic disparities in morbidity and mortality have been identified as being at increased risk for a number of infectious and chronic diseases including asthma, diabetes, pneumonia and seasonal influenza (4,5). The reasons for the increased risk related to influenza are unclear and likely to be multifactorial. Potential explanations may include limited access to healthcare, higher prevalence of underlying chronic disease, lower annual influenza vaccination rates and greater socioeconomic, cultural, educational and linguistic obstacles to the adoption of public health interventions (3,5). The WHO Strategic Advisory Group of Experts (SAGE) on Immunization has mentioned in their latest revision of seasonal influenza vaccination that indigenous populations should be considered as a priority for vaccination (9).
1) Tricco A, Lillie E, Soobiah C, Perrier L, Straus SE. Impact of H1N1 on Socially Disadvantaged Populations: Systematic Review. PLos ONE. 2012;7(6):e39437.
2) World Bank (2011) World Bank Classification. Available: http://data.worldbank.org/about/country-classification/country_and_lending_groups. Accessed Sept 14, 2011.
3) Quinn SC, Kumar S, Freimuth VS, Musa D, Casteneda-Angarita N, Kidwell K. Racial Disparities in Exposure, Susceptibility, and Access to Health Care in the US H1N1 Influenza Pandemic. Am J Public Health. 2011;101(2):285-293.
4) Dee LD, Bensyl DM, Gindler J, Truman BI, Allen BG, D’Mello T, et al. Racial and Ethnic Disparities in Hospitalizations and Deaths Associated with 2009 Pandemic Influenza A (H1N1) Virus Infections in the United States. Ann Epidemiol. 2011;21:623-630.
5) Hutchins SS, Fiscella K, Levine RS, Ompad DC, McDonald M. Protection of Racial/Ethnic Minority Populations During and Influenza Pandemic. Am J Public Health. 2009;99:S261-270.
6) Gonzalez-Candelas F, Astray J, Alonso J, Castro A, Canton R, Galan JC, et al. Sociodemographic Factors and Clinical Conditions Associated to Hospitalization in Influenza A(H1N1) 2009 Virus Infected Patients in Spain, 2009-2010. PLos ONE. 2012;7(3):e33139.
7) La Ruche G, Tarantola A, Barboza P, Vaillant L, Gueguen J, Gastellu-Etchegorry M. The 2009 Pandemic H1N1 Influenza and Indigenous Populations of the Americas and the Pacific. Euro Surveill. 2009,14(42):pii=19366
8) Verrall A, Norton K, Rooker S, Dee S, Olsen L, Tan CE, et al. Hospitalizations for Pandemic (H1N1) 2009 among Maori and Pacific Islanders, New Zealand. Emerging Infectious Diseases. 2010;16(1):100-102.
9) Meeting of the Strategic Advisory Group of Experts on immunization, April 2012 – conclusion and recommendations, Weekly epidemiological record, No. 21, 2012, 87, 201–216