Countries with similar COVID-19 vaccination rates yet divergent outcomes: are all vaccines created equal?

The world is currently engaged in a race of vaccination versus infection in an effort to control the COVID-19 pandemic. Some countries have already achieved high vaccination rates, offering a glimpse into the so-called "post-vaccination" world. We describe here a striking comparison between the similar-sized and neighboring countries of Bahrain and Qatar. While both countries have achieved impressive vaccination rates, cases increased to unprecedented levels in one country while decreasing steadily in the other. Although this could be attributed to a number of factors, we argue here that the heavy reliance on alum-adjuvanted inactivated virus vaccines may have contributed to these discrepant outcomes. We then expand the analysis to compare the outcomes of the top 10 vaccinated countries based on their reliance on inactivated virus vaccines. The results remarkably align with the initial findings seen in Bahrain and Qatar. Countries that did not use inactivated virus vaccines achieved steady declines in daily COVID-19 deaths, while other countries did not. This work highlights the urgent need to further study the effectiveness of alum-adjuvanted inactivated virus vaccines for COVID-19 before expanding their use.