The impact of COVID-19 vaccination coverage on reducing disease burden: A data-driven analysis comparing higher income and lower income countries

COVID-19 (coronavirus disease 2019) vaccination remains a key preventive measure against the current pandemic. As of March 25, 2022, the World Health Organization (WHO) reported 476,374,234 confirmed cases of COVID-19 and more than six million deaths globally. Our motivation in this study was to examine differences in COVID-19 burden between countries (in terms of incidence and mortality), with the goal of answering whether countries with different income levels have different proportions of fully vaccinated individuals per 100,000 populations, whether this results in differences (on average) in COVID-19-specific incidence, mortality, and vaccination coverage, and whether vaccinations reduce the rate of infections and deaths caused by COVID-19. We performed simple one-way ANOVA (analysis of variance) tests as well as Spearman rank correlation analyses. Our results demonstrated that COVID-19 vaccination rates were low in low-income countries (LICs) and lower-middle-income countries (LMICs), and that the rates of recorded cases and deaths were the lowest in these countries as well (almost certainly due to low surveillance rates). In contrast, COVID-19 vaccination rates were high in high-income countries (HICs) and upper-middle-income countries (UMICs), and these countries also showed the highest rates of recorded cases and deaths. The country-level proportion of people receiving COVID-19 vaccines was statistically significantly and negatively correlated with COVID-19 descriptives in HICs and showed negative weak-to-moderate correlations in lower and middle-income countries. However, there is no proof that this association is causative in nature. Our findings inform research directions, policy initiatives, and medical guidelines.