Influenza vaccine to reduce adverse vascular events in patients with heart failure: a multinational randomised, double-blind, placebo-controlled trial

Association between influenza vaccination and prognosis in patients with ischemic heart disease: a systematic review and meta-analysis

BACKGROUND

There is substantial epidemiological evidence demonstrating that influenza contributes to cardiovascular events in patients who already have cardiovascular diseases. However, it is unclear the extent to which influenza vaccination influences the prognosis of patients with ischemic heart disease (IHD).

METHODS

We conducted a search for eligible randomized controlled trials (RCTs) in PubMed, Cochrane, and Embase on March 11, 2024, to investigate the effect of the influenza vaccine on the prognosis of patients with IHD. The effect sizes were combined using random-effects models, and the Trial Sequential Analysis (TSA) was used to assess the reliability and validity of the results.

RESULTS

Five RCTs with a total of 5,659 patients with IHD were included. Use of influenza vaccine reduced the risk of major cardiovascular events (risk ratio [RR]=0.67, 95% confidence interval [CI] 0.52-0.87, number-needed-to-treat [NNT] of 37, high certainty), cardiovascular death (RR=0.55, 95%CI 0.35-0.87, moderate certainty), all-cause mortality (RR=0.58, 95%CI 0.40-0.84, high certainty) and myocardial infarction (MI) (RR=0.66, 95%CI 0.46-0.93, high certainty) in patients with IHD compared with control. The analysis revealed no significant benefit regarding hospitalization for heart failure (HF) (RR=0.91, 95%CI 0.21-3.99, moderate certainty) and revascularization (RR=0.59, 95%CI 0.10-3.45, moderate certainty). The NNT to avoid 1 event was 37 for major adverse cardiovascular events (MACE), 56 for cardiovascular death, 67 for MI, 41 for all-cause death. TSA showed that the benefit of influenza vaccine in reducing MACE was conclusive.

CONCLUSION

These studies suggested that the use of influenza vaccine may reduce the risk of MACE in patients with IHD.

Recent advances in the influenza virus vaccine landscape: a comprehensive overview of technologies and trials

SUMMARYIn the United Kingdom (UK) in 2022/23, influenza virus infections returned to the levels recorded before the COVID-19 pandemic, exerting a substantial burden on an already stretched National Health Service (NHS) through increased primary and emergency care visits and subsequent hospitalizations. Population groups ≤4 years and ≥65 years of age, and those with underlying health conditions, are at the greatest risk of influenza-related hospitalization. Recent advances in influenza virus vaccine technologies may help to mitigate this burden. This review aims to summarize advances in the influenza virus vaccine landscape by describing the different technologies that are currently in use in the UK and more widely. The review also describes vaccine technologies that are under development, including mRNA, and universal influenza virus vaccines which aim to provide broader or increased protection. This is an exciting and important era for influenza virus vaccinations, and advances are critical to protect against a disease that still exerts a substantial burden across all populations and disproportionately impacts the most vulnerable, despite it being over 80 years since the first influenza virus vaccines were deployed.

Influenza vaccination in patients with acute heart failure (PANDA II): study protocol for a hospital-based, parallel-group, cluster randomized controlled trial in China

BACKGROUND

Influenza vaccination confers broad benefits in the elderly and certain high-risk populations, but its effectiveness in patients with acute heart failure (HF) is uncertain. Rates of influenza vaccination are low in China due to poor awareness, cultural misunderstandings, and cost.

AIMS

To determine the effectiveness of influenza vaccination in patients with acute HF admitted to hospitals in China.

METHODS

The second Population Assessment of Influenza and Disease Activity (PANDA II) study is a two-arm, parallel-group, county-level hospital-based, cluster randomized controlled trial to determine the benefits and risks of full access to routine free influenza vaccination before hospital discharge, compared to routine limited use of influenza vaccination, on the primary endpoint of death or hospital readmission. Consecutive hospitalized patients at each site are enrolled to a target of 50 participants in each autumn-winter influenza outbreak period (October to March) over 3 consecutive years to reach the required sample size. Patients are centrally followed up at 1, 3, 6, and 12 months after hospital discharge (or death if earlier). Site numbers varied across year according to predicted influenza activity and logistical reasons.

CONCLUSIONS

This study offers a unique chance to clarify uncertainties surrounding the effectiveness of influenza vaccination in patients with HF and to lay the groundwork for future prevention strategies.

TRIAL REGISTRATION

This trial was registered with the acronym PANDA II (Population Assessment of Influenza and Disease Activity) at ChiCTR.org.cn (ChiCTR2100053264). Registered on 17 November 2021.

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. We investigated the following outcomes: Hospitalizations for pneumonia or influenza, respiratory hospitalizations, cardio-respiratory hospitalizations, cardiovascular hospitalizations, all-cause hospitalizations, and all-cause death. Outcomes were analysed as recurrent events. Cumulative numbers of events were assessed weekly. Cumulative relative effectiveness estimates were calculated and descriptively compared with influenza circulation. The trial is registered at Clinicaltrials.gov: NCT05048589.

RESULTS

Among 12,477 randomly assigned participants, receiving QIV-HD was associated with lower incidence rates of hospitalizations for pneumonia or influenza (10 vs. 33 events, incidence rate ratio [IRR] 0.30 [95% CI, 0.14-0.64]; p 0.002) and all-cause hospitalizations (647 vs. 742 events, IRR 0.87 [95% CI, 0.76-0.99]; p 0.032) compared with QIV-SD. Trends favouring QIV-HD were consistently observed over time including in the period before active influenza transmission; i.e. while the first week with a ≥10% influenza test positivity rate was calendar week 10, 2022, the first statistically significant reduction in hospitalizations for pneumonia or influenza was already observed by calendar week 3, 2022 (5 vs. 15 events, IRR 0.33 [95% CI, 0.11-0.94]; p 0.037).

DISCUSSION

In a post-hoc analysis, QIV-HD was associated with lower incidence rates of hospitalizations for pneumonia or influenza and all-cause hospitalizations compared with QIV-SD, with trends evident independent of influenza circulation levels. Our exploratory results correspond to a number needed to treat of 65 (95% CI 35-840) persons vaccinated with QIV-HD compared with QIV-SD to prevent one additional all-cause hospitalization per season. Further research is needed to confirm these hypothesis-generating findings.

Influenza vaccine in cardiovascular disease: Current evidence and practice in India

Influenza is a common trigger for cardiovascular events. Temporal association studies of influenza and cardiovascular events have well documented this phenomenon. More recently, randomised clinical trials of influenza vaccine have shown the benefit of immunisation in reducing recurrent cardiovascular events, especially in patients with acute coronary syndrome. Despite this overwhelming benefit, its uptake in India is very low. This could be due to a lack of awareness and paucity of evidence of its benefit in tropical countries like India, where the influenza season is variable and spread throughout the year. In this review, we explore these aspects of influenza and cardiovascular diseases and discuss the way ahead.

Influenza Vaccination and Cardiovascular Events in Japanese Patients With Heart Failure - Findings From the PARALLEL-HF Trial

Background

Influenza is associated with an increased risk for cardiovascular events in patients with heart failure (HF). This study aimed to investigate the prevalence of influenza vaccination among Japanese patients with HF enrolled in the PARALLEL-HF (Prospective comparison of ARNI with ACEi to determine the noveL beneficiaL trEatment vaLue in Japanese Heart Failure patients) trial and the association between receiving influenza vaccination and cardiovascular events including death or HF hospitalization.

Methods and Results

In PARALLEL-HF, in which 223 patients with HF and reduced ejection fraction (HFrEF) were randomized to the angiotensin-receptor neprilysin inhibitor (sacubitril/valsartan) or enalapril, 97 (43%) received influenza vaccination. Influenza vaccination tended to be associated, though statistically not significant, with a lower risk for all-cause death (adjusted hazard ratio [HR]: 0.67; 95% confidence interval [CI]: 0.32-1.39) and cardiopulmonary or influenza-related hospitalization or death (adjusted HR: 0.72; 95% CI: 0.46-1.11) in propensity score-adjusted models.

Conclusions

The influenza vaccination rate in Japanese patients with HFrEF who were well managed on guideline-directed medical therapy was suboptimal despite recommendations from clinical practice guidelines. However, importantly, it could be associated with better clinical benefits.

High-intensity care for GDMT titration

Heart failure (HF) is a systemic disease associated with a high risk of morbidity, mortality, increased risk of hospitalizations, and low quality of life. Therefore, effective, systemic treatment strategies are necessary to mitigate these risks. In this manuscript, we emphasize the concept of high-intensity care to optimize guideline-directed medical therapy (GDMT) in HF patients. The document highlights the importance of achieving optimal recommended doses of GDMT medications, including beta-blockers, renin-angiotensin-aldosterone inhibitors, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter inhibitors to improve patient outcomes, achieve effective, sustainable decongestion, and improve patient quality of life. The document also discusses potential obstacles to GDMT optimization, such as clinical inertia, physiological limitations, comorbidities, non-adherence, and frailty. Lastly, it also attempts to provide possible future scenarios of high-intensive care that could improve patient outcomes.

Influenza vaccination for heart failure patients: a cost-effectiveness analysis from the perspective of Chinese healthcare system

Purpose

Influenza infection induces cardiovascular events in heart failure (HF) patients, with potential risk reduction through vaccination. This study aims to evaluate the cost-effectiveness of influenza vaccination for HF patients in China.

Methods

We developed a Markov model with a 3-month cycle to simulate the cost-effectiveness of administering the influenza vaccine to patients with HF over a 3-year period. Patients in the model received either the influenza vaccine or a placebo, in addition to standard HF treatment. Cost data, sourced from the China Healthcare Statistic Yearbook and other public records, and effectiveness data from the IVVE (Influenza Vaccine to Prevent Adverse Vascular Events in HF) trial, were incorporated. Specifically, the cost of the influenza vaccine was 75 Chinese Yuan (CNY) (11 USD), the cost of hospitalization for heart failure (HHF) was 9,326 CNY (1,386 USD), and the cost of treatment for pneumonia was 5,984 CNY (889 USD). The study's primary outcome, the incremental cost-effectiveness ratio (ICER), quantifies the incremental cost (CNY and USD) per incremental quality-adjusted life year (QALY). Additional outcomes included total cost, total effectiveness, incremental cost, and incremental effectiveness. We conducted one-way and probabilistic sensitivity analyses (PSA) to assess certainty and uncertainty, respectively. Scenario analysis, considering various situations, was performed to evaluate the robustness of the results.

Results

In the base case analysis, influenza vaccine, compared to placebo, among Chinese HF patients, resulted in a cost increase from 21,004 CNY (3,121 USD) to 21,062 CNY (3,130 USD) and in QALYs from 1.89 to 1.92 (2.55 life years vs. 2.57 life years) per patient. The resulting ICER was 2,331 CNY (346 USD) per QALY [2,080 CNY (309 USD) per life year], falling below the willingness-to-pay threshold based on per capita GDP. One-way sensitivity analysis revealed that disparities in HHF and cardiovascular death rates between groups had the most significant impact on the ICER, while the cost of vaccines had a marginal impact. PSA and scenario analysis collectively affirmed the robustness of our findings.

Conclusion

This study suggests that adding the influenza vaccine to standard treatment regimens for Chinese patients with HF may represent a highly cost-effective option. Further real-world data studies are essential to validate these findings.

Association of respiratory infections and the impact of vaccinations on cardiovascular diseases

Influenza, pneumococcal, severe acute respiratory syndrome coronavirus 2, and respiratory syncytial virus infections are important causes of high morbidity and mortality in the elderly. Beyond the burden of infectious diseases, they are also associated with several non-infectious complications like cardiovascular events. A growing body of evidence in prospective studies and meta-analyses has shown the impact of influenza and pneumococcal vaccines on types of cardiovascular outcomes in the general population. Influenza vaccination showed a potential benefit for primary and secondary prevention of cardiovascular diseases across all ages. A reduced risk of cardiovascular events for individuals aged 65 years and older was associated with pneumococcal vaccination. Despite scientific evidence on the effectiveness, safety, and benefits of the vaccines and recommendations to vaccinate elderly patients and those with risk factors, vaccination rates remain sub-optimal in this population. Doubts about vaccine necessity or efficacy and concerns about possible adverse events in patients and physicians refer to delayed acceptance. Vaccination campaigns targeting increasing professional recommendations and public perceptions should be implemented in the coming years. The aim of this review paper is to summarize the effect of vaccination in the field of cardiovascular disease to achieve a higher vaccination rate in this patient population.

Effects of high-dose versus standard-dose quadrivalent influenza vaccine among patients with diabetes: A post-hoc analysis of the DANFLU-1 trial

AIM

High-dose quadrivalent influenza vaccine (QIV-HD) has been shown to be more effective than standard-dose (QIV-SD) in reducing influenza infection, but whether diabetes status affects relative vaccine effectiveness (rVE) is unknown. We aimed to assess rVE on change in glycated haemoglobin [HbA1c (∆HbA1c)], incident diabetes, total all-cause hospitalizations (first + recurrent), and a composite of all-cause mortality and hospitalization for pneumonia or influenza.

METHODS

DANFLU-1 was a pragmatic, open-label trial randomizing adults (65-79 years) 1:1 to QIV-HD or QIV-SD during the 2021/22 influenza season. Cox proportional hazards regression was used to estimate rVE against incident diabetes and the composite endpoint, negative binomial regression to estimate rVE against all-cause hospitalizations, and ANCOVA when assessing rVE against ∆HbA1c.

RESULTS

Of the 12 477 participants, 1162 (9.3%) had diabetes at baseline. QIV-HD, compared with QIV-SD, was associated with a reduction in the rate of all-cause hospitalizations irrespective of diabetes [overall: 647 vs. 742 events, incidence rate ratio (IRR): 0.87, 95% CI (0.76-0.99); diabetes: 93 vs. 118 events, IRR: 0.80, 95% CI (0.55-1.15); without diabetes: 554 vs. 624 events, IRR: 0.88, 95% CI (0.76-1.01), pinteraction = 0.62]. Among those with diabetes, QIV-HD was associated with a lower risk of the composite outcome [2 vs. 11 events, HR: 0.18, 95% CI (0.04-0.83)] but had no effect on ∆HbA1c; QIV-HD adjusted mean difference: ∆ + 0.2 mmol/mol, 95% CI (-0.9 to 1.2). QIV-HD did not affect the risk of incident diabetes [HR 1.18, 95% CI (0.94-1.47)].

CONCLUSIONS

In this post-hoc analysis, QIV-HD versus QIV-SD was associated with an increased rVE against the composite of all-cause death and hospitalization for pneumonia/influenza, and the all-cause hospitalization rate irrespective of diabetes status.

Influenza vaccination for elderly, vulnerable and high-risk subjects: a narrative review and expert opinion

Influenza is associated with a substantial health burden, especially in high-risk subjects such as older adults, frail individuals and those with underlying chronic diseases. In this review, we summarized clinical findings regarding the impact of influenza in vulnerable populations, highlighted the benefits of influenza vaccination in preventing severe illness and complications and reviewed the main evidence on the efficacy, effectiveness and safety of the vaccines that are best suited to older adults among those available in Italy. The adverse outcomes associated with influenza infection in elderly and frail subjects and those with underlying chronic diseases are well documented in the literature, as are the benefits of vaccination (mostly in older adults and in patients with cardiovascular diseases, diabetes and chronic lung disease). High-dose and adjuvanted inactivated influenza vaccines were specifically developed to provide enhanced immune responses in older adults, who generally have low responses mainly due to immunosenescence, comorbidities and frailty. These vaccines have been evaluated in clinical studies and systematic reviews by international immunization advisory boards, including the European Centre for Disease Prevention and Control. The high-dose vaccine is the only licensed influenza vaccine to have demonstrated greater efficacy versus a standard-dose vaccine in preventing laboratory-confirmed influenza in a randomized controlled trial. Despite global recommendations, the vaccination coverage in high-risk populations is still suboptimal. All healthcare professionals (including specialists) have an important role in increasing vaccination rates.

Cardiologists' knowledge and perceptions of the seasonal influenza immunisation

BACKGROUND

Seasonal influenza immunisation reduces cardiovascular events in high-risk patients, but 50% do not receive routine immunisation. The perceptions and current role of cardiologists in recommending and prescribing influenza immunisation has not been well described.

METHODS

We used an exploratory sequential mixed methods design. Semi-structured interviews of 10 cardiologists were performed to identify themes for quantitative evaluation. 63 cardiologists undertook quantitative evaluation in an online survey. The interviews and surveys addressed (a) attitudes and behaviours regarding influenza immunisation and (b) preventative care in cardiology.

RESULTS

One quarter (25.4%, n = 16) of cardiologists recommended influenza immunisation to all patients. Less than half (49.2%, n = 31) recommended influenza immunisation to secondary prevention patients. Almost 1/3 of respondents (31.7%, n = 20) were uncertain or unaware of the guidelines regarding influenza immunisation and patients with cardiac disease. Most cardiologists believed that general practitioners were responsible for ensuring patients received influenza immunisation (76.2%, n = 48).

CONCLUSIONS

Despite reducing cardiovascular events in high-risk patients, influenza immunisation is not widely recommended by cardiologists. Further clinician education is needed to address the knowledge gaps which prevent recommendation and uptake of this guideline directed treatment.

The association between influenza vaccination, cardiovascular mortality and hospitalization: A living systematic review and prospective meta-analysis

BACKGROUND

The effects of seasonal influenza vaccination on cardiovascular disease (CVD) outcomes, including among individuals with established CVD, are uncertain.

METHODS

To evaluate the efficacy and safety of influenza vaccines compared to no vaccines or placebo for preventing all-cause/CVD mortality or all-cause/CVD hospitalization in the general population and in populations with pre-existing CVD, we conducted a living systematic review (LSR) and prospective meta-analysis (PMA). Published randomized controlled trials (RCT) and observational studies between 1994 and 2023 were searched. PRISMA guidelines were followed in the extraction of study details, and risk of bias was assessed using the Cochrane tools. Analyses were stratified by study design and CVD history. Study quality was evaluated using GRADE system. Meta analyses based on random-effects models were performed between July and October 2022. Pooled risk ratios (RRs) for all-cause/CVD mortality and all-cause/CVD hospitalization were main outcomes.

RESULTS

Six published RCTs comprising 12,662 participants (mean age, 62 years; 45 % women; 8,797 with pre-existing CVD) and 37 observational studies comprising 6,311,703 participants (mean age, 49 years; 50 % women; 1,189,955 with pre-existing CVD) were included. Only those RCTs judged to be low risk were included in the analyses, and observational studies at anything greater than moderate risk of bias were excluded. In RCTs, influenza vaccine was not significantly associated with lower all-cause mortality (RR, 0.85; 95 %CI, 0.61-1.17), cardiovascular death (RR, 0.80; 95 %CI, 0.60-1.07), or CVD hospitalization (RR, 0.69; 95 %CI, 0.47-1.02). A statistically significant reduction in all-cause hospitalization (RR, 0.86; 95 %CI, 0.76-0.97) was observed. The evidence level was assessed as moderate for all-cause hospitalization, and low for other outcomes. Overall, observational studies suggested a stronger protective association between influenza vaccination and outcomes, except for CVD hospitalization. Based on RCTs, there was no difference in the effects of influenza vaccination on all-cause mortality among the general population compared to those with pre-existing CVD, although the summary point estimate favored benefits only in those with pre-existing CVD.

CONCLUSIONS

While observational studies suggest that influenza vaccination may be associated with lower all-cause and CVD mortality and all-cause hospitalization, RCTs reported to date suggest a reduction in the risk of all-cause hospitalization but do not provide clear evidence to support preventive effects on mortality (all-cause or CVD) or CVD hospitalization.

Influenza vaccine effect on risk of stroke occurrence: a systematic review and meta-analysis

Background

Stroke is a significant global cause of mortality and long-term disability, potentially influenced by infections that heighten systemic inflammation and thrombotic events. The full impact of influenza vaccination on stroke remains uncertain. This systematic review and meta-analysis aimed to investigate the association between influenza immunization and stroke incidence.

Methods

We searched for randomized controlled trials (RCTs), case-control, and cohort studies published in PubMed/Medline, Cochrane-Central-Register-of-Controlled-Trials (CENTRAL), and Embase until 5 December 2022, and identified articles investigating the effect of influenza vaccine on stroke occurrence. All articles were screened by two independent reviewers. We performed a meta-analysis to investigate the risk of stroke occurrence in vaccinated vs. unvaccinated individuals. The random-effects model was used in all statistical analyses.

Results

Among the 26 articles meeting our criteria, 10 were retrospective cohort studies, 9 were case-control studies, 3 were prospective cohort studies, 3 were RCTs and 1 case-series. Overall, the studies showed a significant decrease in the risk of stroke incidence/hospitalization among vaccinated patients (OR = 0.81, 95% CI [0.77-0.86], p = 0.00001). Furthermore, studies showed flu vaccine decreases the occurrence of mortality among stroke patients (OR = 0.50, 95% CI [0.37-0.68], p = 0.00001). Sub-group analysis revealed significant protective effect for patients with specific comorbidities including atrial fibrillation (OR = 0.68, 95% CI [0.57-0.81], p = 0.0001), diabetes (OR = 0.76, 95% CI [0.66-0.87], p = 0.0001), Chronic obstructive pulmonary disease (OR = 0.70, 95% CI [0.61-0.81], p = 0.00001), and hypertension (OR = 0.76, 95% CI [0.70-83], p = 0.00001).

Conclusion

The current meta-analysis further supports prior findings that influenza vaccination reduces stroke risk, particularly in patients with comorbidities. Guidelines should promote vaccination for at-risk individuals.

Immunizing hearts: exploring the vaccination frontier in heart failure management

Heart failure (HF) is a widespread clinical condition that affects numerous individuals globally and is a leading cause of hospitalization, particularly in the elderly population. Despite efforts to manage HF using various pharmacological and nonpharmacological interventions, mortality and hospitalization rates remain alarmingly high. Preventive vaccination has emerged as a key measure endorsed by cardiology societies for reducing the morbidity and mortality associated with HF. This study undertakes an extensive review of existing literature to explore the role of vaccination in managing HF, focusing specifically on the immunological pathways involved and potential benefits offered by immunization in this context. This article highlights the role of various vaccines, including influenza, pneumococcal, and COVID-19 vaccines, in reducing HF-related hospitalization, mortality, and overall disease burden. Additionally, this article will delve into specific vaccines that have shown promise in HF management, such as influenza, pneumococcal, and COVID-19 vaccines, along with the rationale for their use, clinical trials, meta-analyses, and real-world data supporting their effectiveness in patients with HF. This article also considers potential challenges and obstacles to widespread vaccination in individuals with HF, which include vaccine hesitancy, accessibility, and adverse events related to vaccines.

The association between influenza vaccination and the perception of COVID-19 as well as COVID-19 vaccination behavior among community residents in Anhui province, China

Influenza is a significant public health threat associated with high morbidity and mortality globally. This study investigated the influenza vaccination rate (IVR) among community residents in Anhui province, China, and explored the association between participants' influenza vaccination and their key sociodemographic characteristics, perception of COVID-19 as well as COVID-19 vaccination behavior. We found that the IVR among respondents in Anhui province was 27.85% in 2020. Regression analyses revealed that males (OR = 1.41, 95% CI: 1.01 ~ 1.96), residents with above middle school education (OR = 1.88, 95% CI: 1.04 ~ 3.39), considered themselves likely to be infected with COVID-19 (OR = 1.53, 95% CI: 1.04 ~ 2.24), had received the COVID-19 vaccine (OR = 9.85, 95% CI: 3.49 ~ 27.78), did not plan to receive COVID-19 vaccine in the future (OR = 1.70, 95% CI: 1.17 ~ 2.47), and had no adverse reactions after COVID-19 vaccination (OR = 1.54, 95% CI: 1.04 ~ 2.27) were associated with a higher IVR. The acceptance of influenza vaccination was mainly associated with respondents' gender, education, perception of COVID-19, history of COVID-19 vaccination in city and countryside community residents in Anhui province.

Association of recent respiratory illness and influenza with acute myocardial infarction among the Bangladeshi population: A case-control study

Current evidence suggests that recent acute respiratory infections and seasonal influenza may precipitate acute myocardial infarction (AMI). This study examined the potential link between recent clinical respiratory illness (CRI) and influenza, and AMI in Bangladesh. Conducted during the 2018 influenza season at a Dhaka tertiary-level cardiovascular (CV) hospital, it included 150 AMI cases and two control groups: 44 hospitalized cardiac patients without AMI and 90 healthy individuals. Participants were matched by gender and age groups. The study focused on self-reported CRI and laboratory-confirmed influenza ascertained via quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) within the preceding week, analyzed using multivariable logistic regression. Results showed that cases reported CRI, significantly more frequently than healthy controls (27.3% vs. 13.3%, adjusted odds ratio (aOR): 2.21; 95% confidence interval (CI): 1.05-4.06), although this was not significantly different from all controls (27.3% vs. 22.4%; aOR: 1.19; 95% CI: 0.65-2.18). Influenza rates were insignificantly higher among cases than controls. The study suggests that recent respiratory illnesses may precede AMI onset among Bangladeshi patients. Infection prevention and control practices, as well as the uptake of the influenza vaccine, may be advocated for patients at high risk of acute CV events.

Influenza vaccination and major cardiovascular risk: a systematic review and meta-analysis of clinical trials studies

Cardiovascular events remain a substantial global health concern, necessitating innovative strategies for prevention. This study aims to assess the potential impact of influenza vaccination on major cardiovascular events. A search of the medical English literature was conducted using PubMed/MEDLINE, EMBASE, and the Cochrane CENTRAL up to 1 August 2023. Meta-analysis and stratified analyses were performed to investigate specific outcomes, including myocardial infarction (MI), cardiovascular death, and stroke. Pooled relative risks (RR) along with their 95% confidence intervals (CI) were calculated to evaluate the associations. A comprehensive analysis was conducted on a total of 9059 patients, with 4529 patients receiving the influenza vaccine and 4530 patients receiving a placebo. Among patients who received the influenza vaccine, a notable reduction in the occurrence of major cardiovascular events was observed, with 517 cases compared to 621 cases in the placebo group (RR 0.70; 95% CI 0.55-0.91). The stratified analysis revealed a decreased risk of MI in vaccinated patients (RR 0.74; 95% CI 0.56-0.97) and a significant reduction in cardiovascular death events (RR 0.67; 95% CI 0.45-0.98). This study provides compelling evidence that influenza vaccination is associated with a decreased risk of major cardiovascular events, particularly myocardial infarction, and cardiovascular death. These findings highlight the potential of influenza vaccination as an adjunctive strategy in cardiovascular disease prevention. Further research and exploration of underlying mechanisms are warranted to elucidate the observed beneficial effects.

Temporal Association Among Influenza-Like Illness, Cardiovascular Events, and Vaccine Dose in Patients With High-Risk Cardiovascular Disease: Secondary Analysis of a Randomized Clinical Trial

Importance

Influenza-like illness (ILI) activity has been associated with increased risk of cardiopulmonary (CP) events during the influenza season. High-dose trivalent influenza vaccine was not superior to standard-dose quadrivalent vaccine for reducing these events in patients with high-risk cardiovascular (CV) disease in the Influenza Vaccine to Effectively Stop Cardio Thoracic Events and Decompensated Heart Failure (INVESTED) trial.

Objective

To evaluate whether high-dose trivalent influenza vaccination is associated with benefit over standard-dose quadrivalent vaccination in reducing CP events during periods of high, local influenza activity.

Design, Setting, and Participants

This study was a prespecified secondary analysis of INVESTED, a multicenter, double-blind, active comparator randomized clinical trial conducted over 3 consecutive influenza seasons from September 2016 to July 2019. Follow-up was completed in July 2019, and data were analyzed from September 21, 2016, to July 31, 2019. Weekly Centers for Disease Control and Prevention (CDC)-reported, state-level ILI activity was ascertained to assess the weekly odds of the primary outcome. The study population included 3094 patients with high-risk CV disease from participating centers in the US.

Intervention

Participants were randomized to high-dose trivalent or standard-dose quadrivalent influenza vaccine and revaccinated for up to 3 seasons.

Main Outcomes and Measures

The primary outcome was the time to composite of all-cause death or CP hospitalization within each season. Additional measures included weekly CDC-reported ILI activity data by state.

Results

Among 3094 participants (mean [SD] age, 65 [12] years; 2309 male [75%]), we analyzed 129 285 person-weeks of enrollment, including 1396 composite primary outcome events (1278 CP hospitalization, 118 deaths). A 1% ILI increase in the prior week was associated with an increased risk in the primary outcome (odds ratio [OR], 1.14; 95% CI, 1.07-1.21; P < .001), CP hospitalization (OR, 1.13; 95% CI, 1.06-1.21; P < .001), and CV hospitalization (OR, 1.12; 95% CI, 1.04-1.19; P = .001), after adjusting for state, demographic characteristics, enrollment strata, and CV risk factors. Increased ILI activity was not associated with all-cause death (OR, 1.00; 95% CI, 0.88-1.13; P > .99). High-dose compared with standard-dose vaccine did not significantly reduce the primary outcome, even when the analysis was restricted to weeks of high ILI activity (OR, 0.88; 95% CI, 0.65-1.20; P = .43). Traditionally warmer months in the US were associated with lower CV risk independent of local ILI activity.

Conclusions and Relevance

In this secondary analysis of a randomized clinical trial, ILI activity was temporally associated with increased CP events in patients with high-risk CV disease, and a higher influenza vaccine dose did not significantly reduce temporal CV risk. Other seasonal factors may play a role in the coincident high rates of ILI and CV events.

Trial Registration

ClinicalTrials.gov Identifier: NCT02787044.

Pleiotropic Effects of Influenza Vaccination

Influenza vaccines are designed to mimic natural influenza virus exposure and stimulate a long-lasting immune response to future infections. The evolving nature of the influenza virus makes vaccination an important and efficacious strategy to reduce healthcare-related complications of influenza. Several lines of evidence indicate that influenza vaccination may induce nonspecific effects, also referred to as heterologous or pleiotropic effects, that go beyond protection against infection. Different explanations are proposed, including the upregulation and downregulation of cytokines and epigenetic reprogramming in monocytes and natural killer cells, imprinting an immunological memory in the innate immune system, a phenomenon termed "trained immunity". Also, cross-reactivity between related stimuli and bystander activation, which entails activation of B and T lymphocytes without specific recognition of antigens, may play a role. In this review, we will discuss the possible nonspecific effects of influenza vaccination in cardiovascular disease, type 1 diabetes, cancer, and Alzheimer's disease, future research questions, and potential implications. A discussion of the potential effects on infections by other pathogens is beyond the scope of this review.

Cluster randomized trial of influenza vaccination in patients with acute heart failure in China: A mixed-methods feasibility study

Uncertainties about the efficacy of influenza vaccination for populations with heart failure (HF) in preventing cardiovascular outcomes, as well as lack of effective vaccination strategies, may contribute to low vaccine coverage rate (VCR) in China and globally. We assessed the feasibility of a strategy to promote influenza vaccines in patients hospitalized with acute HF in China and to inform the design of a hybrid effectiveness-implementation cluster randomized trial to evaluate this strategy on mortality and hospital re-admission. We conducted a cluster randomized pilot trial involving 11 hospitals in Henan Province in China, with mixed-methods evaluation between December 2020 and April 2021. A process evaluation involved interviews with 51 key informants (patients, health professionals, policy makers). The intervention included education about influenza vaccination and availability of free vaccines administered prior to hospital discharge for HF patients, while usual care included attending community-based points of vaccination (PoV) for screening and vaccination. Implementation outcomes focused on reach, fidelity, adoption, and acceptability. Recruitment rates were assessed for trial feasibility. Effectiveness outcomes were influenza VCR, HF-specific rehospitalizations and mortality at 90 days. A total of 518 HF patients were recruited from 7 intervention and 4 usual care hospitals (mean of 45 participants per hospital per month). VCR was 89.9% (311/346, 86.1-92.8%) in the intervention group and 0.6% (1/172, 0.0-3.7%) in the control group. The process evaluation demonstrated reach to patients with lower socioeconomic and education status. There was good fidelity of the intervention components, with education and PoV set up processes being adapted to local hospital workflow and workforce capacity. Intervention was acceptable and adopted by patients and health professionals. However, outside of a trial setting, concerns were raised around vaccination reimbursement costs, workforce accountability and capacity. The intervention strategy appears feasible and acceptable for improving VCR in HF patients at county-level hospitals in China. Trial registration: This pilot trial is registered with the acronym PANDA II Pilot (Population Assessment of Influenza and Disease Activity) at ChiCTR.org.cn (ChiCTR2000039081).