We read with interest the article by Frohlich and Potvin, which argues very eloquently against populations-at-risk interventions and proposes that population approaches should be complemented with interventions in vulnerable groups.1 These groups are characterized by shared social conditions, such as lack of resources, which are fundamental causes of disease that place them at increased risk of risks.2 Although this notion is certainly valid as an overall public health framework, the limitations of such a strategy must also be recognized. Here we present 3 epidemiological scenarios to illustrate that the population-at-risk approach should not be neglected as a crucial intervention strategy to advance population health and reduce health disparities.
Communicable Disease Transmission.
Elevated infectious disease incidence or prevalence in certain populations poses a threat, not only to individuals, but also to society at large. High tuberculosis (TB) rates in prisons in the former Soviet Union served as a reservoir that contributed to the overall resurgence of TB in the general population.3 Thus, in the case of communicable diseases, interventions should target the population at risk.4 In such cases, doing so prevents other individuals from being exposed to communicable diseases. Furthermore, focusing efforts on the entire population would not effectively interrupt transmission, particularly when the high-risk groups represent a small proportion of the population. High coverage achieved with a universal intervention would be inefficacious and mask possible low coverage in the hard-to-reach high-risk groups. As a result, active transmission foci would go unnoticed.5
Immediate Versus Long-Term Benefits.
We agree that macrosocial interventions are essential long-term strategies to ameliorate living and working conditions of vulnerable groups, although they are slow acting at best.6,7 Timely interventions targeting populations at risk could attenuate specific health threats in the short run and reduce mortality and morbidity. Although this approach does not directly address underlying social conditions of vulnerable populations, it nevertheless serves an important role in public health practice.
Exposure Prevalence.
Exposure prevalence might differ between groups. High exposure levels might precipitate high disease levels and, therefore, justify interventions in populations at risk. For example, diarrheal disease transmission through contaminated water supplies can be interrupted by intervening with home chlorination devices to disinfect contaminated drinking water in populations at risk.8 Similarly, the promotion of physical activity has been shown to reduce obesity in African American girls from low-income families.9
In summary, macrosocial interventions should include the population approach and focus on vulnerable populations. Simultaneously, however, more-immediate interventions should be implemented in populations at risk to advance both population health and health equity.
Contributors J. C. Semenza conceptualized and wrote the initial draft of the letter. J. Suk and D. Manissero contributed to the discussion and editing of the letter.
References
- 1.Frohlich KL, Potvin L. Transcending the known in public health practice: the inequality paradox: the population approach and vulnerable populations. Am J Public Health 2008;98:216–221. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Link BG, Phelan J. Social conditions as fundamental causes of disease. J Health Soc Behav. 2003;80–94. [PubMed]
- 3.Shilova MV, Dye C. The resurgence of tuberculosis in Russia. Philos Trans R Soc Lond B Biol Sci. 2001; 356:1069–1075. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Semenza JC, Giesecke J. Intervening to reduce inequalities in infections in Europe. Am J Public Health. 2008;98:787–792. Published online April 1, 2008. doi:10.2105/AJPH.2007.120329. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Manissero D, Lopalco PL, Levy-Bruhl D, Ciofi degli Atti ML, Giesecke J. Assessing the impact of different BCG vaccination strategies on severe childhood TB in low-intermediate prevalence settings. Vaccine. Published online March 11, 2008. doi: 10.1016/j.vaccine.2008.02.038. [DOI] [PubMed]
- 6.Semenza JC, Maty S. Acting upon the macrosocial environment to improve health: a framework for intervention. In: Galea S, ed. Macrosocial Determinants of Population Health. New York, NY: Springer Media Publishing; 2007:443–461.
- 7.Semenza JC. Case studies: improving the macrosocial environment. In: Galea S, ed. Macrosocial Determinants of Population Health. New York, NY: Springer Media Publishing; 2007:463–484.
- 8.Semenza JC, Roberts L, Henderson A, Bogan J, Rubin CH. Water distribution system and diarrheal disease transmission: a case study in Uzbekistan. Am J Trop Med Hyg. 1998;59:941–946. [DOI] [PubMed] [Google Scholar]
- 9.Robinson TN, Killen JD, Kraemer HC, et al. Dance and reducing television viewing to prevent weight gain in African-American girls: the Stanford GEMS pilot study. Ethn Dis. 2003;13(suppl 1):S65–S77. [PubMed] [Google Scholar]