Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta Georgia, USA.
Clin Infect Dis. 2022 Aug 24;75(1):170-175. doi: 10.1093/cid/ciab1016.
Relative vaccine effectiveness (rVE) are metrics commonly reported to compare absolute VE (aVE) of 2 vaccine products.
Estimates of rVE for enhanced influenza vaccines (eIV) vs standard inactivated influenza vaccine (IIV) have been assessed across different seasons, influenza-specific endpoints, and nonspecific endpoints (eg, all-cause cardiovascular hospitalizations). To illustrate the challenges of comparability across studies, we conducted a scenario analysis to evaluate the effects of varying absolute VE (aVE) of IIV (ie, as compared with placebo) on the interpretation of rVE of eIV vs IIV.
We show that estimates of rVE might not be comparable across studies because additional benefits commensurate with a given estimate of rVE are dependent on the aVE for the comparator vaccine, which can depend on factors such as host response to vaccine, virus type, and clinical endpoint evaluated.
These findings have implications for interpretation of rVE across studies and for sample size considerations in future trials.
相对疫苗效力（rVE）是用于比较两种疫苗产品绝对疫苗效力（aVE）的常用指标。
我们评估了不同季节、流感特异性终点和非特异性终点（例如，全因心血管住院）中，增强型流感疫苗（eIV）与标准灭活流感疫苗（IIV）的 rVE 估计值。为了说明跨研究可比性的挑战，我们进行了情景分析，以评估 IIV 的绝对疫苗效力（aVE）（即与安慰剂相比）变化对 eIV 与 IIV 的 rVE 解释的影响。
我们表明，由于与给定 rVE 估计值相称的额外益处取决于比较疫苗的 aVE，而 aVE 又取决于宿主对疫苗的反应、病毒类型和评估的临床终点等因素，因此 rVE 的估计值在不同研究之间可能无法比较。
这些发现对跨研究解释 rVE 以及对未来试验的样本量考虑具有重要意义。
