*3.1. Selection of Sources*

Our search identified 7784 items (after removing duplicates) that were considered for inclusion. After screening titles and abstracts, 315 were retained for full-text review. A total of 148 items were excluded at the full-text review stage because the study objective was not relevant, the criteria for COVID-19 vaccination coverage was not met, the article type did not meet the inclusion criteria, the criteria for dimension of inequality was not met, the article only reported between-country inequality or there was insufficient information to assess eligibility. In total, 167 articles were included from which data were extracted (Figure 1).

**Figure 1.** PRISMA flow diagram depicting stages of selecting sources for a scoping review about inequalities in COVID-19 vaccination coverage.

The included articles were published in 2021 (43 articles) or 2022 (124 articles), across a total of 82 academic journals (Supplementary Materials S3). Journals represented by five or more included articles were: *Vaccines* (18 articles); *Morbidity and Mortality Weekly Report* (15 articles); *Vaccine* (11 articles); *International Journal of Environmental Research and Public Health* and *PLoS One* (7 articles each); and *BMJ Open* (5 articles). The articles were of variable lengths and scope/depth of analysis, context and discussion. To provide an indication of the type of articles included, we categorised them as full research papers (around six pages or longer, with greater analytical scope and contextual detail) or short research papers (around five pages or less with more limited analytical and contextual detail). The article type designated by the journal also informed the categorisation. Most included articles were designated as full research papers (119 articles, including 1 review), with the remaining designated as short research papers (48 articles).

#### *3.2. Study Characteristics*
