Relative effectiveness of high-dose versus standard-dose influenza vaccine against hospitalizations and mortality according to frailty score: A post-hoc analysis of the DANFLU-1 randomized trial.

Background: Frailty is a risk factor for adverse influenza-related outcomes. We assessed the effectiveness of high-dose (HD-IIV) versus standard-dose (SD-IIV) influenza vaccination according to frailty score (FS).

Methods: This was a post-hoc analysis of the randomized feasibility trial of HD-IIV versus SD-IIV conducted during the 2021-2022 influenza season in older adults aged 65-79 years.

Immunogenicity and safety of quadrivalent recombinant influenza vaccine in Korean adults: Phase III, randomized study.

Quadrivalent recombinant influenza vaccine (RIV4) is indicated for active immunization against influenza virus in adults (≥18 years) in countries where it is currently registered. This Phase III, parallel, randomized, modified double-blind, active controlled, multi-center study was designed to compare the immunogenicity and safety of single dose intramuscular RIV4 with a locally-licensed quadrivalent-inactivated influenza vaccine (IIV4, Fluarix® quadrivalent) in participants aged ≥18 years during 2021-22 Northern Hemisphere influenza season at three tertiary care centers in South Korea. Participants were randomized (1:1) to receive single dose intramuscular RIV4 or IIV4.

Relative Effectiveness of High-Dose Versus Standard-Dose Quadrivalent Influenza Vaccine in Older Adults With Cardiovascular Disease: A Prespecified Analysis of the DANFLU-1 Randomized Clinical Trial.

Background: Influenza vaccination reduces the risk of adverse outcomes in patients with cardiovascular disease (CVD). We sought to evaluate whether the presence of CVD modified the relative effectiveness of the high-dose quadrivalent influenza vaccine (QIV-HD) versus standard-dose quadrivalent influenza vaccine (QIV-SD) in this prespecified analysis of the DANFLU-1 trial (Feasibility of Randomizing Danish Citizens Aged 65-79 Years to High-Dose Quadrivalent Influenza Vaccine Versus Standard-Dose Quadrivalent Influenza Vaccine in a Pragmatic Registry-Based Setting).

Methods: DANFLU-1 was a pragmatic, open-label, randomized feasibility trial of QIV-HD versus QIV-SD in adults aged 65 to 79 years during the 2021/2022 influenza season in Denmark.

High-Dose Quadrivalent Influenza Vaccine for Prevention of Cardiovascular and Respiratory Hospitalizations in Older Adults.

Background: We assessed the relative vaccine effectiveness (rVE) of high-dose quadrivalent influenza vaccine (QIV-HD) versus standard-dose quadrivalent influenza vaccine (QIV-SD) in preventing respiratory or cardiovascular hospitalizations in older adults.

Methods: FinFluHD was a phase 3b/4 modified double-blind, randomized pragmatic trial. Enrolment of 121,000 adults ≥65 years was planned over three influenza seasons (October to December 2019-2021).

Clinical Outcomes With Electronic Nudges to Increase Influenza Vaccination : A Prespecified Analysis of a Nationwide, Pragmatic, Registry-Based, Randomized Implementation Trial.

Background: In the NUDGE-FLU (Nationwide Utilization of Danish Government Electronic letter system for increasing inFLUenza vaccine uptake) trial, electronic letters incorporating cardiovascular (CV) gain-framing and repeated messaging increased influenza vaccination by approximately 1 percentage point.

Objective: To evaluate the effects of the successful nudging interventions on downstream clinical outcomes.

Design: Prespecified exploratory analysis of a nationwide randomized implementation trial.

A Pragmatic Randomized Feasibility Trial of Influenza Vaccines.

BACKGROUND: The relative vaccine effectiveness (rVE) of high-dose quadrivalent influenza vaccines (QIV-HD) versus standard-dose quadrivalent influenza vaccines (QIV-SD) against hospitalizations and mortality in the general older population has not been evaluated in an individually randomized trial. Because of the large sample size required, such a trial will need to incorporate innovative, pragmatic elements. METHODS: We conducted a pragmatic, open-label, active-controlled, randomized feasibility trial in Danish citizens aged 65 to 79 years during the 2021–2022 influenza season.

Effectiveness of high-dose versus standard-dose quadrivalent influenza vaccine against recurrent hospitalizations and mortality in relation to influenza circulation: A post-hoc analysis of the DANFLU-1 randomized clinical trial.

Objectives: To evaluate the relative effectiveness of high-dose quadrivalent influenza vaccine (QIV-HD) versus standard-dose quadrivalent influenza vaccine (QIV-SD) against recurrent hospitalizations and its potential variation in relation to influenza circulation.

Methods: We did a post-hoc analysis of a pragmatic, open-label, randomized trial of QIV-HD versus QIV-SD performed during the 2021-2022 influenza season among adults aged 65-79 years. Participants were enrolled in October 2021-November, 2021 and followed for outcomes from 14 days postvaccination until 31 May, 2022.

Electronically Delivered Nudges to Increase Influenza Vaccination Uptake in Older Adults With Diabetes: A Secondary Analysis of the NUDGE-FLU Trial.

Importance: Influenza vaccination is associated with a reduced risk of mortality in patients with diabetes, but vaccination rates remain suboptimal.

Objective: To assess the effect of electronic nudges on influenza vaccination uptake according to diabetes status.

Design, Setting, And Participants: The NUDGE-FLU (Nationwide Utilization of Danish Government Electronic Letter System for Increasing Influenza Vaccine Uptake) trial was a nationwide clinical trial of Danish citizens 65 years or older that randomized participants at the household level to usual care or 9 different electronic nudge letters during the 2022 to 2023 influenza season.

Electronic nudges to increase influenza vaccination uptake among patients with heart failure: A pre-specified analysis of the NUDGE-FLU trial.

Aims: Seasonal influenza vaccination is strongly recommended in patients with heart failure (HF). The NUDGE-FLU trial recently found two electronic behavioural nudging letter strategies - a letter highlighting potential cardiovascular benefits of vaccination and a repeated letter at day 14 -effective in increasing influenza vaccination in Denmark. The aims of this pre-specified analysis was to further examine vaccination patterns and effects of these behavioural nudges in patients with HF including potential off-target effects on guideline-directed medical therapy (GDMT) use.

Electronic nudges to increase influenza vaccination uptake in Denmark: a nationwide, pragmatic, registry-based, randomised implementation trial.

Background: Influenza vaccination rates remain suboptimal despite effectiveness in preventing influenza infection and related complications. We investigated whether behavioural nudges, delivered via a governmental electronic letter system, would increase influenza vaccination uptake among older adults in Denmark.

Methods: We did a nationwide, pragmatic, registry-based, cluster-randomised implementation trial during the 2022-23 influenza season in Denmark.

Effect of Electronic Nudges on Influenza Vaccination Rate in Older Adults With Cardiovascular Disease: Prespecified Analysis of the NUDGE-FLU Trial.

Background: Influenza vaccines have been demonstrated to effectively reduce the incidence of influenza infection and potentially associated risks of cardiovascular events in patients with cardiovascular disease (CVD). Despite strong guideline and public health endorsements, global influenza vaccination rates in patients with CVD are highly variable. This prespecified analysis of NUDGE-FLU (Nationwide Utilization of Danish Government Electronic Letter System for Increasing Influenza Vaccine Uptake) examined the effect of digital behavioral nudges on influenza vaccine uptake based on the presence of CVD.

Nationwide Utilization of Danish Government Electronic letter system for increasing inFLUenza vaccine uptake (NUDGE-FLU): Study protocol for a nationwide randomized implementation trial.

Background: Annual influenza vaccination is widely recommended in older adults and other high-risk groups including patients with cardiovascular disease. The real-world effectiveness of influenza vaccination is limited by suboptimal uptake and effective strategies for increasing vaccination rates are therefore needed. The purpose of this trial is to investigate whether behavioral nudges digitally delivered via the Danish nationwide mandatory governmental electronic letter system can increase influenza vaccination uptake among older adults.

Immunological non-inferiority and safety of a quadrivalent inactivated influenza vaccine versus two trivalent inactivated influenza vaccines in China: Results from two studies.

Who Universal Trial Numbers (utns): U1111-1174-4615 and U1111-1174-4698.

Clinicaltrials.gov: NCT04210349 and NCT03430089.

Immunogenicity and safety of high-dose quadrivalent influenza vaccine in older adults in Taiwan: A phase III, randomized, multi-center study.

Background: High-dose influenza vaccine offers better protection against influenza/associated complications compared with standard-dose formulation. We evaluated immunogenicity and safety of high-dose influenza vaccine (QIV-HD) and standard-dose (QIV-SD) in older adults (≥ 65 years) in Taiwan.

Methods: This was a phase III, randomized, modified double-blind, active-controlled, multi-center, descriptive study in older adults.

Influence of Digital Intervention Messaging on Influenza Vaccination Rates Among Adults With Cardiovascular Disease in the United States: Decentralized Randomized Controlled Trial.

Background: Seasonal influenza affects 5% to 15% of Americans annually, resulting in preventable deaths and substantial economic impact. Influenza infection is particularly dangerous for people with cardiovascular disease, who therefore represent a priority group for vaccination campaigns.

Objective: We aimed to assess the effects of digital intervention messaging on self-reported rates of seasonal influenza vaccination.

Reply to letter to editor by Hadigal et al. regarding the immunogenicity and safety trial of high-dose influenza vaccine in adults aged ≥60 years.

Hadigal et al. argued the recommendation of high-dose influenza vaccine over standard-dose formulation is not supported by comparisons of numbers-needed-to-vaccinate (NNV) nor aligned with the WHO mandate of improving vaccine coverage. However, the authors' NNV calculation was inaccurate.