Note that views expressed in this opinion article are the writer’s personal views and not necessarily those of TrialSite.
Dr. Ron Brown – Opinion Editorial
October 8, 2021
Reuters published a “fact check” article several months ago: Why Relative Risk Reduction, not Absolute Risk Reduction, is most often used in calculating vaccine efficacy. In presenting their arguments, the authors of this article minimized the importance of reporting the absolute risk reduction (ARR) and defended the use of the relative risk reduction (RRR) to represent vaccine efficacy. Yet, the article also mentioned that the ARR is more dependent on group infection rates in a clinical trial, implying that the ARR is a more sensitive and relevant measure for vaccine efficacy than the RRR. For example, the larger the groups in a clinical trial, and the smaller the rate of infected people in the groups, the smaller the absolute risk reduction (ARR), even if the relative risk reduction (RRR) remains the same. This is why both the ARR and RRR of a clinical trial must be reported. The following examples illustrate this effect based on formulas for calculating the ARR, RRR, and the relative risk (RR)—a meth...
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