These 9 domains were derived from the index-defined domains in the Table. Most index-defined domain names were used or matched across indices, which had slight variations in domain naming. “Epidemiological Factors” were renamed as “Health.” All different “environmental” or “neighborhood”-specific factors were grouped under “Environmental and Neighborhood.” The colored bars indicate percentage composition of each index by the number of variables in author-constructed domains. Because the SVI and CCVI weight all variables equally, the percentages shown are representative of true domain share in index construction based on the number of variables included for those indices. ADI indicates Area Deprivation Index; CCVI, COVID-19 Community Vulnerability Index; HPI, Healthy Places Index; SVI, Social Vulnerability Index.
eMethods. Grouping of disadvantage index variables and domains under analytic meta-domains.
Srivastava T, Schmidt H, Sadecki E, Kornides ML. Disadvantage Indices Deployed to Promote Equitable Allocation of COVID-19 Vaccines in the US: A Scoping Review of Differences and Similarities in Design. JAMA Health Forum. 2022;3(1):e214501. doi:10.1001/jamahealthforum.2021.4501
To promote equitable allocation of COVID-19 vaccines, expert guidance proposed to incorporate statistical, place-based measures of disadvantage (“disadvantage indices”) into allocation frameworks1 by allocating larger shares of vaccines to disadvantaged communities, planning dispensing site locations, and/or through targeted community outreach.1,2 Disadvantage indices combine metrics such as income, housing quality, and education, enabling ranking at a particular geographic unit, such as the census tract. By the end of March 2021, the majority of US states (n = 37) used various disadvantage indices to inform COVID-19 vaccine allocation and planning, but these indices differ in design.2 Our objective was to review the construction and defined purpose of indices deployed during the initial COVID-19 vaccine rollout.
All Centers for Disease Control and Prevention jurisdictional health departments’ websites were queried in a structured search from November 2020 to March 2021 to retrieve COVID-19 vaccination allocation plans, as documented in a previously published review.2 Institutional review board review was not required owing to the use of publicly available index data sets that did not contain human participants’ information. Two authors (T.S. and E.S.) extracted index design methods and data from source websites or published methods articles, and 2 authors (H.S. and M.L.K.) reviewed extracted data (eMethods in the Supplement). Indices without publicly available methods and data were excluded. Categories used for index characterization are shown in the Table.
We identified 8 indices,2 of which 4 had publicly available methods and data and were included in this review: Area Deprivation Index (ADI),3 COVID-19 Community Vulnerability Index (CCVI),4 Healthy Places Index (HPI),5 and Social Vulnerability Index (SVI)6 (Table, Figure). The ADI is intended to be a general planning and health policy tool.3 The CCVI focuses specifically on COVID-19.4 The HPI measures how various social determinants of health influence life expectancy at birth in California.5 The SVI, the most widely used index, centers on responses to natural disasters.2,6 Indices capture communities at differing geographic levels: block group (600-3000 people), census tract (1200-8000 people), zip code, and county. The HPI also ranks by numerous administrative areas (eg, school districts). The ADI, CCVI, and SVI report national and state-level rankings. The HPI reports rankings specific to California (Table). Indices range from 15 (SVI) to 40 variables (CCVI). We grouped 78 total variables that indices use under 9 overarching domains based on index-defined domains: population demographics, poverty, education and employment, racial and ethnic minority populations, housing and transportation, high-risk transmission environments, health, health care system, and environmental and neighborhood. Indices largely source variables from the American Community Survey.
While all indices were used to promote equitable vaccine allocation, we found similarities and differences in index construction across geographic reporting units, number of variables, and weighting strategies. The ADI reports the most granular geographic units (block groups), compared with the CCVI and SVI (census tracts). Larger geographic units may mask heterogeneities in “disadvantage” in population-dense settings, such as larger cities, and may lead to underestimation of disadvantage. However, because most data are available at the census tract, one can favor pragmatically trading off accuracy for comprehensiveness of data. Additional variation is found in indices’ variable weighting, for which some indices rely on factor score coefficients (ADI) while others have fixed weights for each domain, resulting in differences even among indices with similar variables, affecting the broader concept of “disadvantage” that is captured. While this study does not quantify allocation trade-offs, it provides an important perspective on considering indices’ role and what would have happened absent their use.
The uptake of disadvantage indices to promote social justice in the initial allocation of COVID-19 vaccines was unprecedented, rapid, and widespread.2 It continues to be relevant during vaccination of children aged 5 to 11 years, where using indices within a tool such as the Vaccine Equity Planner (https://vaccineplanner.org) can help identify so-called vaccine deserts, as well as for prioritizing outreach and vaccination site planning for boosters and initial vaccinations as the Omicron variant amplifies the fourth COVID-19 wave. Likewise, indices hold promise for promoting equity in the allocation plans for recently approved pharmaceutical treatments. All indices used appear to be associated with benefiting vulnerable communities compared with not using an index, but future research should identify the advantages and disadvantages associated with the use of one index vs another for specific purposes.2
Accepted for Publication: November 4, 2021.
Published: January 21, 2022. doi:10.1001/jamahealthforum.2021.4501
Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2022 Srivastava T et al. JAMA Health Forum.
Corresponding Author: Tuhina Srivastava, MPH, Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Blockley Hall, 423 Guardian Dr, Room 107, Philadelphia, PA 19104 (firstname.lastname@example.org).
Author Contributions: All authors had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Srivastava, Schmidt, Kornides.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Srivastava, Schmidt, Kornides.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Srivastava.
Administrative, technical, or material support: Srivastava, Schmidt.
Supervision: Schmidt, Kornides.
Conflict of Interest Disclosures: Dr Kornides reported receiving grants from National Institutes of Health/National Institute of Child Health and Human Development/Office of Research on Women's Health (NIH/NICHD/ORWH 5 K12 HD085848-04/05) during the conduct of the study. No other disclosures were reported.
Funding/Support: Dr Kornides and Mrs Srivastava were supported by the Philadelphia Community Engagement Alliance Against COVID-19 Disparities.
Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Additional Contributions: We are grateful for comments from Barry E. Flanagan, PhD, Elaine J. Hallisey, MA, Danielle Sharpe, PhD, and the Public Health Alliance of Southern California data team on an earlier version of the manuscript. They were not compensated for these contributions.