Relative Vaccine Effectiveness of Adjuvanted Trivalent Influenza Vaccine over Three Consecutive Influenza Seasons in the United States

Relative effectiveness of adjuvanted versus non-adjuvanted influenza vaccines in older adults with risk factors for influenza complications during the 2019-2020 U.S. influenza season

This study estimated the relative vaccine effectiveness (rVE) of the MF59®-adjuvanted trivalent influenza vaccine (aTIV) versus standard-dose nonadjuvanted egg-based quadrivalent influenza vaccines (QIVe) for the prevention of influenza-related medical encounters (IRMEs), outpatient IRMEs, and influenza- and pneumonia-related hospitalizations during the 2019-2020 US influenza season among adults ≥65 years of age who had ≥1 high-risk condition. A secondary objective evaluated the rVE of aTIV versus QIVe in preventing these outcomes among older adults with specific high-risk conditions. This retrospective cohort study included US adults ≥65 years of age vaccinated with aTIV or QIVe between August 1, 2019, and January 31, 2020. Exposures, covariates, risk factors, and outcomes were captured from a linked dataset comprised of electronic health records (EHR) (Veradigm Network EHR) linked to insurance claims (Komodo Healthcare Map). A doubly robust approach was applied wherein multivariable-adjusted odds ratios were derived using inverse probability of treatment-weighted samples to calculate rVEs and 95 % confidence interval independently for individuals ≥1 high-risk condition and those with specific high-risk conditions. The study included 954,707 aTIV and 719,125 QIVe recipients. For all outcomes, aTIV was more effective than QIVe among adults ≥65 years of age who had ≥1 high-risk condition (any IMRE: 23.6 % [20.9 %-26.1 %]), outpatient IRME: 23.3 % [20.4 %-26.1 %], and influenza- or pneumonia-related hospitalizations: 19.0 % [16.3 %-21.6 %]), during the 2019-2020 influenza season. Similarly, aTIV was more effective than QIVe at preventing outcomes among individuals with specific high-risk conditions except for body mass index ≥40. This study demonstrated higher effectiveness of aTIV versus QIVe in preventing any IRMEs, outpatient IRMEs, and influenza- or pneumonia-related hospitalizations among adults ≥65 years of age who had ≥1 high-risk condition.

Rollout of the 2022/2023 Seasonal Influenza Vaccination and Correlates of the Use of Enhanced Vaccines among Italian Adults

In Italy, several types of seasonal influenza vaccines (SIVs) are available for older adults, but for the 2022/2023 season there were no guidelines on their specific use. This cross-sectional study assessed the frequency and determinants of the use of enhanced (adjuvanted and high-dose) SIVs in Italian older adults, as compared to standard-dose non-adjuvanted formulations. Of 1702 vaccines administered to a representative outpatient sample of adults aged ≥ 60 years and residing in Genoa, 69.5% were enhanced SIVs. Older age (adjusted odds ratio (aOR) for each 1-year increase 1.10; p < 0.001), and the presence of cardiovascular disease (aOR 1.40; p = 0.011) and diabetes (aOR 1.62; p = 0.005) were associated with the use of enhanced vaccines. Compared with the adjuvanted SIV, subjects immunized with the high-dose vaccine were older (aOR for each 1-year increase 1.05; p < 0.001) and had higher prevalence of respiratory diseases (aOR 1.85; p = 0.052). Moreover, usage of the enhanced SIVs was driven by the period of immunization campaign, place of vaccination and physician. Despite their superior immunogenicity and effectiveness, the adoption of enhanced SIVs in Italy is suboptimal, and should be increased. Enhanced formulations are mostly used in the oldest, and in subjects with some co-morbidities.

[Enhanced targeted influenza vaccines - New evidence shows higher effectiveness in older adults]

Seasonal influenza causes a significant burden of disease in the German population and is associated with high societal costs. Persons aged 60 years and older are particularly at risk due to immunosenescence and chronic disease and account for a large proportion of influenza-associated hospitalizations and deaths. Adjuvanted, high-dose, recombinant and cell-based influenza vaccines have been developed to improve the effectiveness compared with conventional vaccines. Recent observational studies show better effectiveness of adjuvanted vaccine over conventional vaccines and similar effectiveness to the high-dose vaccine in older adults. Some countries have already considered the new evidence in their vaccination recommendations for the current or earlier seasons. The availability of the vaccines for older adults should also be ensured in Germany to guarantee a high level of vaccination protection.