Competing Theories on Global and Regional Vaccine Inequities: A Scoping Literature Review Within the Context of the COVID-19 Pandemic

<b>Background/Objectives</b>: Despite global efforts, COVID-19 revealed severe spatial vaccine inequities, disproportionately affecting low- and middle-income countries (LMICs). Scholars across disciplines proposed numerous-and often competing-terms and theories to explain these disparities. In this review and within the context of the COVID-19 pandemic, we assess the usage, definition, and appropriateness of these terms and their linked theories or frameworks. <b>Methods</b>: We conducted a scoping review aiming to clarify key definitions, concepts, and frameworks of eight prominent terms used in the literature regarding COVID-19 global and/or regional vaccine inequities (i.e., <i>vaccine nationalism</i>, <i>vaccine apartheid</i>, <i>vaccine colonialism</i>, <i>vaccine imperialism</i>, <i>vaccine racism</i>, <i>vaccine diplomacy</i>, <i>vaccine solidarity</i>, and <i>vaccine internationalism</i>). The methodology followed the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines for Scoping Reviews and included papers from January 2020 to the end of October 2024. <b>Results</b>: We included 79 papers in our study. The majority (71%) were published in 2021-2022, with less than one-quarter authored by scholars from LMICs. <i>Vaccine imperialism</i> was consistently defined but rarely used, while <i>vaccine nationalism</i> and <i>vaccine apartheid</i> appeared more frequently with varied meanings. Yet, in most cases, all of these concepts identified economic interests of vaccine-producing countries as the root cause of the observed vaccine inequities. <i>Vaccine diplomacy</i> showed similar ambiguity, viewed by some as worsening inequities and by others as potentially mitigating them. The terms <i>vaccine racism</i>, <i>vaccine colonialism</i>, and <i>vaccine solidarity</i> were not explicitly identified but appear to be embedded within the definitions of other prominent terms detected. <b>Conclusions</b>: Across the preselected terms examined, we found numerous-and often conflicting-definitions, revealing the fragmented and competing understandings of the major drivers fueling global vaccine inequities. This lack of coherence inhibits evidence synthesis or shared theoretical progress but, most importantly, might undermine current and future efforts to address these inequities.