Vaccine efficacy: The implication of using odds ratio and relative risk for the calculation. Which one would you choose?

Abstract

During the last 12 months, COVID-19 became a global problem. Universities and drug companies are working together for the development of treatments. Vaccines appear to be one of the most promising treatments, and trials are completed, and others are ongoing. All these studies tend to use a common comparator, the percentage of vaccine efficacy (VE%), calculated using the following formula VE=(1-RR) x100. A recent study published in a renowned medical journal presented large trial results using a different formula VE=(1-OR) x100. We compared the analysis using relative risk (RR) versus an odds ratio (OR), and we did not find any large difference in the results. Nevertheless, we would advise using RR instead of OR in the interests of accuracy, for best practice.