We sought to gain insights into the determinants of seasonal influenza vaccine (SIV) uptake by conducting an age-stratified analysis (18-64 and 65+) of factors associated with SIV uptake among at-risk adults registered to English practices. Records for at-risk English adults between 2011 and 2016 were identified using the Clinical Practice Research Datalink database. SIV uptake was assessed annually. The associations of patient, practice, and seasonal characteristics with SIV uptake were assessed via cross-sectional and longitudinal analyses, using mixed-effects and general estimating equation logistic regression models. Overall SIV uptake was 35.3% and 74.0% for adults 18-64 and 65+, respectively. Relative to white patients, black patients were least likely to be vaccinated (OR18-64: 0.82 (95% CI: 0.80, 0.85); OR65+: 0.59 (95% CI: 0.56, 0.62)), while Asian patients among 18-64 year olds were most likely to be vaccinated (OR18-64: 1.10 (95% CI: 1.07, 1.13)). Females were more likely than males to be vaccinated among 18-64 year olds (OR18-64: 1.19 (95% CI: 1.18, 1.20)). Greater socioeconomic deprivation was associated with decreased odds of uptake among older patients (OR65+: 0.74 (95% CI: 0.71, 0.77)). For each additional at-risk condition, odds of uptake increased (OR18-64: 2.33 (95% CI: 2.31, 2.36); OR65+: 1.39 (95% CI: 1.38, 1.39)). Odds of uptake were highest among younger patients with diabetes (OR18-64: 4.25 (95% CI: 4.18, 4.32)) and older patients with chronic respiratory disease (OR65+: 1.60 (95% CI: 1.58, 1.63)), whereas they were lowest among morbidly obese patients of all ages (OR18-64: 0.68 (95% CI: 0.67, 0.70); OR65+: 0.97 (95% CI: 0.94, 0.99)). Prior influenza season severity and vaccine effectiveness were marginally predictive of uptake. Our age-stratified analysis uncovered SIV uptake disparities by ethnicity, sex, age, socioeconomic deprivation, and co-morbidities, warranting further attention by GPs and policymakers alike.

BACKGROUND: The high-dose inactivated influenza vaccine (HD-IIV) has demonstrated superior protection against a range of hospitalization end points versus standard-dose inactivated influenza vaccine (SD-IIV), but its effectiveness against specific cardiovascular outcomes and in those with pre-existing cardiovascular disease (CVD) is not well elucidated. METHODS: In a prespecified secondary analysis of the FLUNITY-HD (Pooled Analysis of Methodologically Harmonized Pragmatic Randomized Trials of High-Dose vs. Standard-Dose Influenza Vaccine Against Severe Clinical Outcomes) individual-level pooled data set integrating 2 methodologically harmonized pragmatic, individually randomized trials conducted in Denmark and Spain, we investigated the relative vaccine effectiveness of HD-IIV versus SD-IIV against severe cardiovascular outcomes and according to pre-existing CVD among adults ≥65 years of age. Data were primarily obtained from routine health care databases, with follow-up from 14 days after vaccination to May 31 the following year. RESULTS: The pooled data set encompassed 466 320 individually randomized participants, of whom 107 700 (23.1%) had a history of CVD. HD-IIV reduced the incidence of hospitalization for influenza or pneumonia, cardiorespiratory disease, laboratory-confirmed influenza, and any cause compared with SD-IIV, irrespective of the presence or absence of pre-existing CVD ( P _interaction >0.66 for all outcomes). Compared with the SD-IIV group, the HD-IIV group had a significantly lower incidence of hospitalization for any CVD (HD-IIV, 1.15%, versus SD-IIV, 1.24%; relative vaccine effectiveness, 6.6% [95% CI, 1.6–11.4]; P =0.010), hospitalization for any respiratory disease (HD-IIV, 0.92%, versus SD-IIV, 0.98%; relative vaccine effectiveness, 6.5% [95% CI, 0.7–11.9]; P =0.027), and hospitalization for heart failure (HD-IIV, 0.11%, versus SD-IIV, 0.15%; relative vaccine effectiveness, 21.3% [95% CI, 7.6–33.0]; P =0.003). CONCLUSIONS: In a prespecified pooled analysis of 466 320 individually randomized older adults, HD-IIV reduced the incidence of a wide range of severe cardiovascular and respiratory outcomes compared with SD-IIV, with consistent findings regardless of previous history of CVD. Among cardiovascular outcomes, the protective effect of HD-IIV versus SD-IIV was particularly pronounced against hospitalization for heart failure. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT06506812.

Despite universal recommendation of the 4-dose diphtheria, tetanus, and pertussis (DTaP) vaccine series, coverage and timeliness in the US remain suboptimal. DTaP-containing combination vaccines (i.e. quadrivalent and pentavalent) are presumed to improve vaccine coverage rates and timeliness, but research supporting this claim is limited. We sought to investigate the associations between DTaP-containing vaccine use and adherence to the recommended DTaP immunization schedule among children in the US. Using a large claims database, we identified privately insured children born between 2009 and 2016 that received ≥1 DTaP-containing vaccine and had ≥24 months of enrollment from birth, excluding those with DTaP vaccinations not aligned with approved dose indications. Children were classified by DTaP-containing vaccine receipt: combination vaccines only, stand-alone vaccines only, or a mixture of both. Outcome measures included: 1) completion of the 4-dose series and 2) timely receipt of doses. Outcomes were adjusted for gender, birth year, race, and socioeconomic status. The study cohort contained 412,441 children. Of these, 40.5% (167,084) received combination vaccines only, 14.9% (61,342) received stand-alone vaccines only, and 44.6% (184,015) received a mixture of both. Combination vaccine recipients were nearly 3 times as likely to complete the 4-dose series (OR 2.93 (95% CI: 2.88, 2.99)) and for all doses received, more than 4 times as likely to receive doses on time (OR 4.12 (4.04, 4.21), relative to stand-alone vaccine recipients. Significance disparities in adherence were also observed, where minorities were up to 30% less likely (OR 0.70 (0.68, 0.71)) to complete the 4-dose series and up to 27% less likely (OR 0.73 (0.72, 0.75)) to receive doses on time, relative to white children. Our findings demonstrated that adherence to the recommended DTaP immunization schedule was significantly greater among combination vaccine recipients, relative to stand-alone recipients. Further research is needed to investigate underlying causes of disparities in adherence.

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. Methods and results: The nationwide NUDGE-FLU trial randomized 964 870 Danish citizens ≥65 years to usual care or nine different electronic nudging letter strategies. Letters were delivered through the official Danish electronic letter system. The primary endpoint was the receipt of an influenza vaccine; additional outcomes for this analysis included GDMT use. In this analysis, we also assessed influenza vaccination rates in the overall Danish HF population including those <65 years (n = 65 075). During the 2022–2023 season, influenza vaccination uptake was 71.6% in the overall Danish HF population but this varied considerably with only 44.6% uptake in those <65 years. A total of 33 109 NUDGE-FLU participants had HF at baseline. Vaccination uptake was higher among those on higher levels of baseline GDMT (≥3 classes: 85.3% vs. ≤2 classes: 81.9%; p < 0.001). HF status did not modify the effects of the two overall successful nudging strategies on influenza vaccination uptake (cardiovascular gain-framed letter: pinteraction = 0.37; repeated letter: pinteraction = 0.55). No effect modification was observed across GDMT use levels for the repeated letter (pinteraction = 0.88), whereas a trend towards attenuated effect among those on low levels of GDMT was observed for the cardiovascular gain-framed letter (pinteraction = 0.07). The letters had no impact on longitudinal GDMT use. Conclusions: Approximately one in four patients with HF did not receive influenza vaccination with a pronounced implementation gap in those <65 years where less than half were vaccinated. HF status did not modify the effectiveness of cardiovascular gain-framed and repeated electronic nudging letters in increasing influenza vaccination rates. No unintended negative effects on longitudinal GDMT use were observed. Clinical Trial Registration: ClinicalTrials.gov NCT05542004.

Background: Seasonal influenza may lead to severe complications, including respiratory and cardiovascular disease, that result in considerable healthcare resource utilization (HCRU) and mortality, particularly in older individuals. This real‐world study assessed the burden of influenza and its potential complications in older Japanese adults.Methods: This retrospective claims database analysis (April 2015 to June 2019) included insured individuals aged ≥ 60 years at the start of four consecutive influenza seasons in Japan (October 1 to April 30). The primary endpoint was the incidence of influenza‐related emergency room (ER) and outpatient visits, the incidence of hospitalizations, the probability of 30‐day inpatient mortality, and 60‐day medical costs of influenza or its potential complications.Results: Of 8,974,708 individuals (43.2% male, mean ± standard deviation age 73.8 ± 8.9 years), 370,430 (4.13%) were diagnosed with influenza. Overall, 17.18 (95% confidence interval [CI] 16.32–18.04) and 3893.53 (3880.87–3906.19) per 100,000 individuals had influenza‐related ER and outpatient visits, respectively, and 181.50 (178.71–184.28) per 100,000 individuals were hospitalized for influenza. The incidence of influenza‐related ER visits and hospitalizations for influenza or potential complications and the probability of 30‐day inpatient mortality increased with age.Conclusions: Seasonal influenza and its potential complications represent a substantial burden that increases with age in Japanese individuals.

Each year, millions of individuals develop severe influenza disease globally, and as many as 500 000 individuals die from influenza-associated complications.¹ While most are susceptible to influenza, the risk of influenza-related morbidity and mortality is greatest among specific subgroups, including young children, adults older than 65 years, pregnant women, those with certain chronic health conditions, and those who are immunosuppressed.^2,3