<qa>  What is the primary subgroup analysis?Subgroup analyses will first and foremost be carried out for the primary endpoint and its components. All subgroup analyses of event data will be performed using a proportional hazards model with factors treatment, subgroup, and treatment-subgroup interaction, and will be presented with within-group hazard ratios with 95 confidence intervals and the interaction p-value. The primary subgroup analyses will focus on the STEMI and NSTEMI populations and the effect of intervention in each of the three influenza seasons, with the purpose of evaluating effect in each subgroup. 