Primary prevention of acute cardiovascular events by influenza vaccination: an observational study

Comparing higher-dose and single standard-dose influenza vaccines in preventing cardiovascular events: a meta-analysis with 68,713 patients

INTRODUCTION

This manuscript offers an in-depth comparative examination of the effectiveness of higher-dose (double standard-dose and high-dose) influenza vaccines in contrast to a single standard-dose vaccine when it comes to alleviating major cardiovascular events.

STUDY DESIGN

Meta-Analysis.

METHODS

To conduct this study, an exhaustive search was carried out in the medical English literature using databases such as PubMed/MEDLINE, EMBASE, and the Cochrane CENTRAL until 10 April 2024. The evaluation of associations was achieved through the calculation of pooled relative risks (RRs) accompanied by their corresponding 95% confidence intervals (CIs).

RESULTS

A meticulous analysis encompassed a comprehensive cohort of 68,713 patients. Among these participants, 34,430 individuals were randomly assigned to receive a higher-dose influenza vaccination, whereas 34,283 received the standard influenza vaccination. Contrary to initial expectations, a higher-dose influenza vaccine did not manifest elevated efficacy compared to the standard-dose vaccine in terms of mitigating major cardiovascular events. The computed pooled RR stood at 1.0, accompanied by a 95% CI ranging from 0.93 to 1.10.

CONCLUSION

While this systematic review and meta-analysis did not find a statistically significant advantage of higher-dose influenza vaccines over a single standard-dose vaccine in preventing major cardiovascular events, the observed trend towards risk reduction warrants continued investigation. These findings contribute to the ongoing dialogue surrounding vaccination strategies and their implications for cardiovascular outcomes.

Vaccinations, cardiovascular drugs, hospitalization, and mortality in COVID-19 and Long COVID

OBJECTIVE

To identify highest-risk subgroups for COVID-19 and Long COVID(LC), particularly in contexts of influenza and cardiovascular disease(CVD).

METHODS

Using national, linked electronic health records for England (NHS England Secure Data Environment via CVD-COVID-UK/COVID-IMPACT Consortium), we studied individuals (of all ages) with COVID-19 and LC (2020-2023). We compared all-cause hospitalization and mortality by prior CVD, high CV risk, vaccination status (COVID-19/influenza), and CVD drugs, investigating impact of vaccination and CVD prevention using population preventable fractions.

RESULTS

Hospitalization and mortality were 15.3% and 2.0% among 17,373,850 individuals with COVID-19 (LC rate 1.3%), and 16.8% and 1.4% among 301,115 with LC. Adjusted risk of mortality and hospitalization were reduced with COVID-19 vaccination ≥ 2 doses(COVID-19:HR 0.36 and 0.69; LC:0.44 and 0.90). With influenza vaccination, mortality was reduced, but not hospitalization (COVID-19:0.86 and 1.01, and LC:0.72 and 1.05). Mortality and hospitalization were reduced by CVD prevention in those with CVD, e.g., anticoagulants- COVID:19:0.69 and 0.92; LC:0.59 and 0.88; lipid lowering- COVID-19:0.69 and 0.86; LC:0.68 and 0.90. COVID-19 vaccination averted 245044 of 321383 and 7586 of 8738 preventable deaths after COVID-19 and LC, respectively.

INTERPRETATION

Prior CVD and high CV risk are associated with increased hospitalization and mortality in COVID-19 and LC. Targeted COVID-19 vaccination and CVD prevention are priority interventions.

FUNDING

NIHR. HDR UK.

Laboratory-confirmed respiratory viral infection triggers for acute myocardial infarction and stroke: Systematic review protocol

BACKGROUND

Cardiovascular disease contributes substantially to global mortality and morbidity. Respiratory tract infections, particularly influenza, may trigger an increase in the short-term risk of acute myocardial infarction (AMI) and stroke. Recent studies have also linked this risk to other respiratory viruses, including respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the pathogen-specific relative contributions, the strength of their associations, and overall public health significance are poorly understood. Assuming causal links, understanding, quantifying, and comparing the effects of different pathogens as triggering factors for acute cardiovascular events is critical to guide future research and prevention. Our aim is to conduct a systematic review to examine the relative effects of laboratory-confirmed respiratory virus infections as triggers for acute myocardial infarction and stroke.

METHODS

We will conduct a comprehensive search of Ovid MEDLINE, PubMed, Ovid Embase, Cochrane Library Central Register of Controlled Trials, and Web of Science, from inception to the end of March 2024. Studies capturing respiratory viral infection(s) using laboratory-confirmatory methods, incidence of AMI or stroke (ischaemic or haemorrhagic), and those involving human participants in any country, will be assessed for eligibility. We will include the following analytical epidemiological study types: randomised controlled trials, cohort and case-control studies, self-controlled case series, and case-crossover designs. We will not impose restrictions on the date, language, study population, geographical region, or sample size, to minimise the risk of introducing biases. Search results will be screened for eligibility by two independent reviewers, and discrepancies resolved by consensus and/or arbitration by a third reviewer. We will assess the risk of bias among the included studies by adopting the Cochrane Collaboration tools for randomised and non-randomised studies. The overall quality of studies will be assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. We will examine sources of heterogeneity, and if studies are sufficiently homogeneous, a meta-analysis will be conducted to calculate the pooled effect sizes. Reporting will adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO) registration number: CRD42024494997.

Acute Cardiac Events in Hospitalized Older Adults With Respiratory Syncytial Virus Infection

Importance

Respiratory syncytial virus (RSV) infection can cause severe respiratory illness in older adults. Less is known about the cardiac complications of RSV disease compared with those of influenza and SARS-CoV-2 infection.

Objective

To describe the prevalence and severity of acute cardiac events during hospitalizations among adults aged 50 years or older with RSV infection.

Design, Setting, and Participants

This cross-sectional study analyzed surveillance data from the RSV Hospitalization Surveillance Network, which conducts detailed medical record abstraction among hospitalized patients with RSV infection detected through clinician-directed laboratory testing. Cases of RSV infection in adults aged 50 years or older within 12 states over 5 RSV seasons (annually from 2014-2015 through 2017-2018 and 2022-2023) were examined to estimate the weighted period prevalence and 95% CIs of acute cardiac events.

Exposures

Acute cardiac events, identified by International Classification of Diseases, 9th Revision, Clinical Modification or International Statistical Classification of Diseases, Tenth Revision, Clinical Modification discharge codes, and discharge summary review.

Main Outcomes and Measures

Severe disease outcomes, including intensive care unit (ICU) admission, receipt of invasive mechanical ventilation, or in-hospital death. Adjusted risk ratios (ARR) were calculated to compare severe outcomes among patients with and without acute cardiac events.

Results

The study included 6248 hospitalized adults (median [IQR] age, 72.7 [63.0-82.3] years; 59.6% female; 56.4% with underlying cardiovascular disease) with laboratory-confirmed RSV infection. The weighted estimated prevalence of experiencing a cardiac event was 22.4% (95% CI, 21.0%-23.7%). The weighted estimated prevalence was 15.8% (95% CI, 14.6%-17.0%) for acute heart failure, 7.5% (95% CI, 6.8%-8.3%) for acute ischemic heart disease, 1.3% (95% CI, 1.0%-1.7%) for hypertensive crisis, 1.1% (95% CI, 0.8%-1.4%) for ventricular tachycardia, and 0.6% (95% CI, 0.4%-0.8%) for cardiogenic shock. Adults with underlying cardiovascular disease had a greater risk of experiencing an acute cardiac event relative to those who did not (33.0% vs 8.5%; ARR, 3.51; 95% CI, 2.85-4.32). Among all hospitalized adults with RSV infection, 18.6% required ICU admission and 4.9% died during hospitalization. Compared with patients without an acute cardiac event, those who experienced an acute cardiac event had a greater risk of ICU admission (25.8% vs 16.5%; ARR, 1.54; 95% CI, 1.23-1.93) and in-hospital death (8.1% vs 4.0%; ARR, 1.77; 95% CI, 1.36-2.31).

Conclusions and Relevance

In this cross-sectional study over 5 RSV seasons, nearly one-quarter of hospitalized adults aged 50 years or older with RSV infection experienced an acute cardiac event (most frequently acute heart failure), including 1 in 12 adults (8.5%) with no documented underlying cardiovascular disease. The risk of severe outcomes was nearly twice as high in patients with acute cardiac events compared with patients who did not experience an acute cardiac event. These findings clarify the baseline epidemiology of potential cardiac complications of RSV infection prior to RSV vaccine availability.

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.

Respiratory Syncytial Virus-Associated Respiratory Diseases in Children and Adults

BACKGROUND

Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections (LRTI), particularly in neonates, infants and young children, with approximately 33 million infections worldwide each year. 1-2% of episodes lead to hospitalization. There are hardly any reliable epidemiological figures on hospital - ization in adults, whose burden of disease from RSV is probably markedly underestimated.

METHODS

This review is based on publications retrieved by a selective search in PubMed, with particular attention to recommendations for the prevention of RSV infection.

RESULTS

There is no approved antiviral therapy for clinical practice, but preventive strategies are increasingly becoming available. Passive immunization in infants is well tolerated and highly effective, as is the active vaccination of pregnant women to prevent severe RSV infection in young infants. The former was found to lower the frequency of severe LRTI (5/4037 in the vaccination group vs. 19/4031 individuals in the placebo group), yielding an efficacy of 75.7%; for the latter, the corresponding findings were a reduction to 19/3682 in the vaccination group vs. 62/3676 in the placebo group, or 69.4% efficacy. For the active vaccination of older adults, both a recombinant vaccine with adjuvant and a bivalent vaccine have recently been approved. These, too, are well tolerated and highly effective: the former lowered the frequency of severe LRTI to 1/12466 in the vaccination group vs. 17/12494 in the placebo group (94.1% efficacy), while the latter lowered the frequency of LRTI with 3 or more manifestations to 2/17215 in the vaccination group vs. 14/17069 in the placebo group (85.7% efficacy).

CONCLUSION

The approval of new RSV-specific monoclonal antibodies and active vaccinations enables targeted prevention of RSV infection in the main population groups at risk.

Specific and Nonspecific Effects of Influenza Vaccines

With the introduction of the influenza vaccine in the official immunization schedule of most countries, several data regarding the efficacy, tolerability, and safety of influenza immunization were collected worldwide. Interestingly, together with the confirmation that influenza vaccines are effective in reducing the incidence of influenza virus infection and the incidence and severity of influenza disease, epidemiological data have indicated that influenza immunization could be useful for controlling antimicrobial resistance (AMR) development. Knowledge of the reliability of these findings seems essential for precise quantification of the clinical relevance of influenza immunization. If definitively confirmed, these findings can have a relevant impact on influenza vaccine development and use. Moreover, they can be used to convince even the most recalcitrant health authorities of the need to extend influenza immunization to the entire population. In this narrative review, present knowledge regarding these particular aspects of influenza immunization is discussed. Literature analysis showed that the specific effects of influenza immunization are great enough per se to recommend systematic annual immunization of younger children, old people, and all individuals with severe chronic underlying diseases. Moreover, influenza immunization can significantly contribute to limiting the emergence of antimicrobial resistance. The problem of the possible nonspecific effects of influenza vaccines remains unsolved. The definition of their role as inducers of trained immunity seems essential not only to evaluate how much they play a role in the prevention of infectious diseases but also to evaluate whether they can be used to prevent and treat clinical conditions in which chronic inflammation and autoimmunity play a fundamental pathogenetic role.

In-Hospital influenza vaccination to prevent cardiorespiratory events in the first 45 days after acute coronary syndrome: A prespecified analysis of the VIP-ACS trial

BACKGROUND

Influenza vaccination prevents major cardiovascular events in individuals presenting a recent acute coronary syndrome (ACS), however the early effect of an in-hospital double-dose vaccination strategy remains uncertain.

METHODS

The VIP-ACS was a randomized, pragmatic, multicenter, open-label trial with a blinded-adjudication endpoint. Patients with ACS ≤ 7 days of hospitalization were randomized to an in-hospital double-dose quadrivalent inactivated influenza vaccine (double-dose) or a standard-dose influenza vaccine at 30 days post-randomization. The primary endpoint was a hierarchical composite of death, myocardial infarction, stroke, hospitalization for unstable angina, hospitalization for heart failure, urgent coronary revascularization, and hospitalization for respiratory infections, analyzed with the win ratio (WR) method in short-term follow-up (45-days after randomization).

RESULTS

The trial enrolled 1,801 patients (≥18 years old). Median participant age was 57 years, 70 % were male. There were no significant differences between groups on the primary hierarchical endpoint: there were 5.7 % wins in the double-dose in-hospital group and 5.5 % wins in the standard-dose delayed vaccination group (WR: 1.03; 95 % CI: 0.70---1.53; P = 0.85). In a sensitivity analysis including COVID-19 infection in the hospitalizations for respiratory infections endpoint, overall results were maintained (WR: 1.03; 95 % CI 0.71---1.51; P = 0.87). Results were consistent for major cardiovascular events only (WR: 0.82; 95 % CI: 0.48---1.39; P = 0.46). No serious adverse events were observed.

CONCLUSION

In patients with recent ACS, in-hospital double-dose influenza vaccination did not significantly reduce cardiorespiratory events at 45 days compared with standard-dose vaccination at 30 days post-randomization.

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.