A retrospective cohort study assessing relative effectiveness of adjuvanted versus high-dose trivalent influenza vaccines among older adults in the United States during the 2018–19 influenza season

Comparing the Clinical and Economic Outcomes Associated with Adjuvanted versus High-Dose Trivalent Influenza Vaccine among Adults Aged ≥ 65 Years in the US during the 2019–20 Influenza Season—A Retrospective Cohort Analysis

“…Higher efficacy, effectiveness and immunogenicity of enhanced vaccines compared to standard dose vaccines have been demonstrated by several studies [ 1 , 6 , 7 , 8 , 9 ]. Details of the two enhanced vaccines are described in another study by the authors [ 10 ].…”

“…In the absence of randomized controlled trials comparing the efficacy of aIIV3 and HD-IIV3e, real-world data has been used to evaluate the relative vaccine effectiveness (rVE) of aIIV3 and HD-IIV3e [ 10 , 11 , 12 , 13 , 14 , 15 ]. Two studies from the 2018–2019 influenza season found comparable clinical outcomes between aIIV3 and HD-IIV3e [ 10 , 14 ].…”

“…In the absence of randomized controlled trials comparing the efficacy of aIIV3 and HD-IIV3e, real-world data has been used to evaluate the relative vaccine effectiveness (rVE) of aIIV3 and HD-IIV3e [ 10 , 11 , 12 , 13 , 14 , 15 ]. Two studies from the 2018–2019 influenza season found comparable clinical outcomes between aIIV3 and HD-IIV3e [ 10 , 14 ]. The first study conducted among a Medicare fee-for-service (FFS) population found that aIIV3 was associated with a statistically insignificant rVE against influenza-related hospital encounters compared to HD-IIV3e [ 14 ].…”

“…The second study also found rVE to be comparable in the prevention of influenza-related hospitalization/emergency room (ER) visits. Additionally, aIIV3 was slightly more effective in preventing any cardio-respiratory (CRD)-related hospitalization/ER visit [ 10 ]. Healthcare costs post-vaccination were also evaluated in the second study and found to be comparable [ 10 ].…”

“…Additionally, aIIV3 was slightly more effective in preventing any cardio-respiratory (CRD)-related hospitalization/ER visit [ 10 ]. Healthcare costs post-vaccination were also evaluated in the second study and found to be comparable [ 10 ]. Given that influenza seasons vary each year in terms of timing, duration, activity, and clinical severity due to changes in antigenic composition of the influenza virus [ 1 ], it is important to update estimates for rVE and economic burden each year.…”