Table 1.

Summary of Notation in Equations for Statistical Methods

CI	Confidence Interval
L	Number of primary events in a Cox regression analysis
V	Variance of the estimated log Hazard Ratio in a Cox regression analysis
HR	Hazard ratio
VE	Vaccine efficacy
Δ, δ, δ0	Non-inferiority margins used in Stratum ‘A’
TP, TA	Test statistics using data from Stratum ‘P’ and Stratum ‘A’, respectively
LP	Observed number of events in Stratum ‘P’
L0P	Number of events needed in Stratum ‘P’ alone to achieve 90% statistical power
LA	Observed number of events in Stratum ‘A’
L0A	Number of events needed in Stratum ‘A’ alone to achieve 90% statistical power
HR0, HR1	Experimental vaccine to placebo hazard ratios, under the null and alternative hypotheses, in Stratum ‘P’
VE0	Vaccine efficacy of the experimental vaccine, under the null hypothesis, in Stratum ‘P’
HRP	Estimated experimental vaccine to placebo hazard ratio using data in Stratum ‘P’
HRA	Estimated experimental vaccine to active comparator vaccine hazard ratio using data in Stratum ‘A’
VE*, HR*	Estimated vaccine efficacy and hazard ratio from the placebo-controlled evaluation of the Active Comparator Vaccine
tR	Calendar date when it is no longer proper to continue randomization to placebo
tF	Calendar date when it is no longer proper for participants randomized to placebo to remain on placebo and in follow-up