Masters candidate in Biostatistics, Olivia Zang, will present:

“COVID-19 Vaccine Effectiveness Comparison among Three Approaches”

Plan B Adviser: Haitao Chu

Abstract: Different vaccine effectiveness measurements can lead to different estimates with different interpretations. This study compares three commonly used measurements including 1- risk ratio (1-RR), 1- incidence rate ratio (1-IRR), and 1- hazard ratio (1-HR) and discusses their strengths and weaknesses. A case study of 95,224 participants provided by Mayo clinic for COVID-19 protection is presented at the end to further illustrate how different the measurements are.

The study shows that 1- RR tends to overestimate vaccine effectiveness because of the existing immortal time bias. The 1-HR approach provides the lowest estimate of VE with a similar interpretation of the result with 1-IRR but no need for constant incident or hazard rate. In terms of minimizing bias and satisfaction of assumptions, 1- HR performs the best with estimates of 94.2% for fully vaccinated by Pfizer-BioNTech and 97.2% for fully vaccinated by Moderna.

KEYWORDS: Vaccine effectiveness; risk ratio; incidence rate ratio; hazard ratio; COVID-19; immortal time