Universal access to COVID-19 vaccines has been a decisive element in curbing the pandemic. According to statistics provided by the United Nations Development Programme, as of October 1, 2021, high and upper-middle-income nations had distributed, on average, more than one dose per person. In stark contrast, low-income countries only managed to administer less than 4 doses per 100 individuals. Despite several initiatives aimed at rectifying these disparities, structural inequities—ranging from production limitations, healthcare expenditure constraints, to the accessibility of logistics and technology—have remained major stumbling blocks.

Finding the solutions for a fair playing field in vaccine distribution is a formidable challenge. However, the stark realities revealed through quantifying the impacts of vaccine disparity on low- and middle-income countries (LMICs) underscore the urgent need for resolution. For this reason, we sought to estimate the number of deaths that could have been avoided if LMICs had enjoyed the same vaccine availability as high-income nations. To facilitate this, we developed a mathematical and computational model that considers national demographics, age-structured contact mixing patterns, the effects of non-pharmaceutical interventions (NPIs), the presence of multiple virus strains, and the variable impacts on vaccines' efficacy across 20 LMICs from all WHO regions. This model allowed us to explore a "what if" scenario, with a vaccine abundance comparable to high-income countries like the USA.

Our findings were startling, revealing that more than 50% of the observed deaths could have been averted. What was perhaps even more striking was the finding that even without any additional vaccine doses, if these countries had been able to administer vaccines at the same time as their wealthier counterparts, a notable reduction in fatalities might have been achieved. This reduction could vary greatly, from 6% to as much as 50%, depending on the specific country. The model also underscores the significant point that to counterbalance the vaccine inequality witnessed in LMICs, a more intensive and extended application of non-pharmaceutical interventions would have been essential.

The COVID-19 pandemic has not only exposed but also exacerbated global inequities, with disparities ranging from the uneven ability to implement non-pharmaceutical interventions to unequal access to vaccines. Our study illuminates the devastating consequences of these vaccine inequities in low- and lower-middle-income nations. We urgently need concerted actions to rectify these disparities and ensure equitable vaccine distribution worldwide. Although we seem to have weathered the worst of this pandemic, planning for equitable vaccine access is paramount. It is crucial for limiting the emergence and spread of new COVID-19 variants and for preparing for potential future pandemic threats. Only through global collaboration and solidarity can we effectively combat pandemics and mitigate their societal impacts.