Protective effect of influenza vaccination on cardiovascular diseases: a systematic review and meta-analysis

Vaccines Induce Homeostatic Immunity, Generating Several Secondary Benefits

The optimal immune response eliminates invading pathogens, restoring immune equilibrium without inflicting undue harm to the host. However, when a cascade of immunological reactions is triggered, the immune response can sometimes go into overdrive, potentially leading to harmful long-term effects or even death. The immune system is triggered mostly by infections, allergens, or medical interventions such as vaccination. This review examines how these immune triggers differ and why certain infections may dysregulate immune homeostasis, leading to inflammatory or allergic pathology and exacerbation of pre-existing conditions. However, many vaccines generate an optimal immune response and protect against the consequences of pathogen-induced immunological aggressiveness, and from a small number of unrelated pathogens and autoimmune diseases. Here, we propose an "immuno-wave" model describing a vaccine-induced "Goldilocks immunity", which leaves fine imprints of both pro-inflammatory and anti-inflammatory milieus, derived from both the innate and the adaptive arms of the immune system, in the body. The resulting balanced, 'quiet alert' state of the immune system may provide a jump-start in the defense against pathogens and any associated pathological inflammatory or allergic responses, allowing vaccines to go above and beyond their call of duty. In closing, we recommend formally investigating and reaping many of the secondary benefits of vaccines with appropriate clinical studies.

Estimated Incidence of Hospitalizations and Deaths Attributable to Respiratory Syncytial Virus Infections Among Adults in Germany Between 2015 and 2019

INTRODUCTION

Respiratory syncytial virus (RSV) burden in adults is underestimated mainly due to unspecific symptoms and limited standard-of-care testing. We estimated the population-based incidence of hospitalization and mortality attributable to RSV among adults with and without risk factors in Germany.

METHODS

Weekly counts of hospitalizations and deaths for respiratory, cardiovascular, and cardiorespiratory diseases were obtained (Statutory Health Insurance database, 2015-2019). A quasi-Poisson regression model was fitted to estimate the number of hospitalizations and deaths attributable to RSV as a function of periodic and aperiodic time trends, and viral activity while allowing for potential overdispersion. Weekly counts of RSV and influenza hospitalizations in children < 2 years and adults ≥ 60 years, respectively, were used as viral activity indicators. Models were stratified by age group and risk status (defined as presence of selected comorbidities).

RESULTS

Population-based RSV-attributable hospitalization incidence rates were high among adults ≥ 60 years: respiratory hospitalizations (236-363 per 100,000 person-years) and cardiorespiratory hospitalizations (584-912 per 100,000 person-years). RSV accounted for 2-3% of all cardiorespiratory hospitalizations in this age group. The increase in cardiorespiratory hospitalization risk associated with underlying risk factors was greater in 18-44 year old persons (five to sixfold higher) than in ≥ 75 year old persons (two to threefold higher).

CONCLUSIONS

This is a first model-based study to comprehensively assess adult RSV burden in Germany. Estimated cardiorespiratory RSV hospitalization rates increased with age and were substantially higher in people with risk factors compared to those without risk factors. Our study indicates that RSV, like other respiratory viruses, contributes to both respiratory and cardiovascular hospitalizations. Effective prevention strategies are needed, especially among older adults ≥ 60 years and among adults with underlying risk factors.

Influenza vaccination in older adults and patients with chronic disorders: A position paper from the Portuguese Society of Pulmonology, the Portuguese Society of Diabetology, the Portuguese Society of Cardiology, the Portuguese Society of Geriatrics and Gerontology, the Study Group of Geriatrics of the Portuguese Society of Internal Medicine, and the Portuguese Society of Infectious Diseases and Clinical Microbiology

Influenza affects millions of people worldwide each year and can lead to severe complications, hospitalizations, and even death, especially among vulnerable populations such as older adults and those with chronic medical conditions. Annual vaccination is considered the most effective measure for preventing influenza and its complications. Despite the widespread availability of influenza vaccines, however, vaccination coverage rates remain suboptimal in several countries. Based on the latest scientific evidence and expert opinions on influenza vaccination in older people and patients with chronic disease, the Portuguese Society of Pulmonology (SPP), the Portuguese Society of Diabetology (SPD), the Portuguese Society of Cardiology (SPC), the Portuguese Society of Geriatrics and Gerontology (SPGG), the Study Group of Geriatrics of the Portuguese Society of Internal Medicine (NEGERMI-SPMI), and the Portuguese Society of Infectious Diseases and Clinical Microbiology (SPDIMC) discussed best practices for promoting vaccination uptake and coverage and drew up several recommendations to mitigate the impact of influenza. These recommendations focus on the efficacy and safety of available vaccines; the impact of influenza vaccination on older adults; patients with chronic medical conditions, namely cardiac and respiratory conditions, diabetes, and immunosuppressive diseases; and health care professionals, optimal vaccination timing, and strategies to increase vaccination uptake and coverage. The resulting position paper highlights the critical role that vaccinations play in promoting public health, raising awareness, and encouraging more people to get vaccinated.

Estimated causal effects of common respiratory infections on cardiovascular risk: a meta-analysis

OBJECTIVE

Literature supports associations between common respiratory tract infections (RTIs) and risk of cardiovascular diseases, yet the importance of RTIs for cardiovascular risk management remains less understood. This systematic review and meta-analysis aimed to estimate the causal effects of RTIs on occurrence of cardiovascular diseases in the general population.

METHODS

MEDLINE and EMBASE were systematically searched up to 4 November 2022. Eligible were all aetiological studies evaluating risk of cardiovascular outcomes after exposure to common RTIs within any follow-up duration. Evidence was pooled using random-effects models if data allowed. The ROBINS-E and GRADE approaches were used to rate risk of bias and certainty of evidence, respectively. All assessments were performed in duplicate.

RESULTS

We included 34 studies (65 678 650 individuals). Most studies had a high risk of bias. COVID-19 likely increases relative risk (RR (95% CI)) of myocardial infarction (3.3 (1.0 to 11.0)), stroke (3.5 (1.2 to 10)), pulmonary embolism (24.6 (13.5 to 44.9)) and deep venous thrombosis (7.8 (4.3 to 14.4)) within 30 days after infection (GRADE: moderate) and about twofold within 1 year (GRADE: low to moderate). Other RTIs also likely increase the RR of myocardial infarction (2.9 (95% CI 1.8 to 4.9)) and stroke (2.6 (95% CI 1.1 to 6.4)) within 30 days (GRADE: moderate), and to a lesser extent with longer follow-up.

CONCLUSIONS

RTIs likely increase the risk of cardiovascular diseases about 1.5-5 fold within 1 month after infection. RTIs may, therefore, have clinical relevance as target for cardiovascular risk management, especially in high-risk populations.

PROSPERO REGISTRATION NUMBER

CRD42023416277.

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.

Association of pneumococcal vaccination with cardiovascular diseases in older adults: The vaccine effectiveness, networking, and universal safety (VENUS) study

The protective effect of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) against cardiovascular disease has been investigated in the United States and Europe; however, its effect has not been fully established. This study aimed to investigate the protective effect of PPSV23 on cardiovascular events in adults aged ≥ 65 years. This population-based nested case-control study was conducted using the claims data and vaccine records between April 2015 and March 2020 from the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) Study. PPSV23 vaccination was identified using vaccination records in each municipality. The primary outcome was acute myocardial infarction (AMI) or stroke. The adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for PPSV23 vaccination were calculated using conditional logistic regression. Among 383,781 individuals aged ≥ 65 years, 5,356 and 25,730 individuals with AMI or stroke were matched with 26,753 and 128,397 event-free controls, respectively. Individuals who were PPSV23 vaccinated, compared with the unvaccinated individuals, had significantly lower odds of AMI or stroke events (aOR, 0.70 [95% CI, 0.62-0.80] and aOR, 0.81 [95% CI, 0.77-0.86], respectively). More recent PPSV23 vaccination was associated with lower odds ratios (AMI, aOR 0.55 [95% CI, 0.42-0.72] for 1-180 days and aOR 1.11 [95% CI, 0.84-1.47] for 720 days or longer; stroke, aOR 0.83 [95% CI, 0.74-0.93] for 1-180 days and aOR 0.90 [95% CI, 0.78-1.03] for 720 days or longer). Among Japanese older adults, individuals who were PPSV23 vaccinated, compared with unvaccinated individuals, had significantly lower odds of AMI or stroke events.

Antiviral Approaches against Influenza Virus

Preventing and controlling influenza virus infection remains a global public health challenge, as it causes seasonal epidemics to unexpected pandemics. These infections are responsible for high morbidity, mortality, and substantial economic impact. Vaccines are the prophylaxis mainstay in the fight against influenza. However, vaccination fails to confer complete protection due to inadequate vaccination coverages, vaccine shortages, and mismatches with circulating strains. Antivirals represent an important prophylactic and therapeutic measure to reduce influenza-associated morbidity and mortality, particularly in high-risk populations. Here, we review current FDA-approved influenza antivirals with their mechanisms of action, and different viral- and host-directed influenza antiviral approaches, including immunomodulatory interventions in clinical development. Furthermore, we also illustrate the potential utility of machine learning in developing next-generation antivirals against influenza.

Improving service efficiency and throughput of cardiac surgery patients using Monte Carlo simulation: a queueing setting

Bed occupancy rate (BOR) is important for healthcare policymakers. Studies showed the necessity of using simulation approach when encountering complex real-world problems to plan the optimal use of resources and improve the quality of services. So, the aim of the present study is to estimate average length of stay (LOS), BOR, bed blocking probability (BBP), and throughput of patients in a cardiac surgery department (CSD) using simulation models. We studied the behavior of a CSD as a complex queueing system at the Farshchian Hospital. In the queueing model, customers were patients and servers were beds in intensive care unit (ICU) and post-operative ward (POW). A computer program based on the Monte Carlo simulation, using Python software, was developed to evaluate the behavior of the system under different number of beds in ICU and POW. The queueing simulation study showed that, for a fixed number of beds in ICU, BOR in POW decreases as the number of beds in POW increases and LOS in ICU increases as the number of beds in POW decreases. Also, based on the available data, the throughput of patients in the CSD during 800 days was 1999 patients. Whereas, the simulation results showed that, 2839 patients can be operated in the same period. The results of the simulation study clearly demonstrated the behavior of the CSD; so, it must be mentioned, hospital administrators should design an efficient plan to increase BOR and throughput of patients in the future.

Secular trends and determinants of influenza vaccination uptake among patients with cardiovascular disease in Korea: Analysis using a nationwide database

Background

Influenza vaccination reduces cardiovascular events in patients with cardiovascular disease (CVD). Identifying the factors that affect influenza vaccination uptake can help improve the prognosis in patients with CVD. This study aimed to evaluate the secular trends of influenza vaccination uptake and factors associated with lack of vaccination in individuals with CVD.

Materials and methods

We analyzed the annual trends and factors associated with influenza vaccination among 3,264 patients with CVD, included from the Korea National Health and Nutrition Examination Survey which reflect the health and nutritional status of the nationwide population of Korea conducted between 2007/2008 and 2018/2019. We used a stratified, multistage sampling method.

Results

The influenza vaccination rate was greater in patients with CVD (53–74%) than in those without CVD (28–40%). Multivariable logistic regression analysis showed that age <50 years [odds ratio (OR), 16.22; 95% confidence interval (CI), 7.72–34.07], 50–64 years (OR, 6.71; 95% CI, 4.37–10.28), male sex (OR, 1.45; 95% CI, 1.14–1.65), and asthma (OR, 0.45; 95% CI, 0.22–0.92) were independently associated with a lack of influenza vaccination. Among patients aged <65 years, smoking (OR, 2.30; 95% CI, 1.31–4.04), college graduation status (OR, 1.81; 95% CI, 1.16–2.82), and hypertension (OR, 0.70; 95% CI, 0.51–0.95) were independently associated with influenza vaccination. For individuals aged 65years, there was no significant determinant of lack of vaccination.

Conclusion

In patients with CVD, a continuous increase in the secular trend of influenza vaccination was demonstrated in Korea. Young age, male sex, and non-asthma status were independently associated with lack of influenza vaccination uptake.

Effectiveness of influenza vaccination on in-hospital death and recurrent hospitalization in older adults with cardiovascular diseases

OBJECTIVES

There is limited evidence on the effectiveness of influenza vaccination on hospitalization outcomes by cardiovascular disease (CVD) subtypes or comorbidities.

METHODS

This study involved 713,488 records of hospitalization of adults ≥60 years with CVD from the Beijing Urban Employee Basic Medical Insurance database. Logistic regression with generalized estimating equations was conducted to estimate the effectiveness of influenza vaccination on in-hospital death and recurrent hospitalization, adjusting for unmeasured confounders.

RESULTS

The coverage of influenza vaccination was only 13.3% among older adults hospitalized for CVD. Influenza vaccination was associated with 15% (odds ratios 0.85 [0.74, 0.99]) lower risk of in-hospital death among patients with CVD, with stronger associations in patients with stroke. Influenza vaccination was associated with 6% (0.94 [0.88, 0.99]) and 28% (0.72 [0.56, 0.93]) lower risks of recurrent hospitalization for ischemic heart disease (IHD) and respiratory disease in patients with IHD, but there were no clear associations in patients with stroke. For in-hospital death, the protective association of influenza vaccination was stronger in patients with fewer comorbidities and was similar to that of joint vaccinations of influenza and pneumococcal vaccinations.

CONCLUSION

The protective association of influenza vaccination on CVD hospitalization outcomes serves as the evidence base to increase the uptake of influenza vaccination among older adults in China.

Early risk of acute myocardial infarction following hospitalization for severe influenza infection in the middle-aged population of Hong Kong

Introduction

Despite evidence suggesting an association between influenza infection and increased risk of acute myocardial infarction (AMI) in the older adult population (aged 65 years or above), little is known about its near-term risks in middle-aged adults (aged 45 to 64 years). This study aims to estimate the risks of and association between severe influenza infection requiring hospitalization and subsequent AMI within 12 months in middle-aged adults.

Method

This is a retrospective case-control analysis of territorywide registry data of people aged 45 to 64 years admitting from up to 43 public hospitals in Hong Kong during a 20-year period from January 1997 to December 2017. The exposure was defined as severe influenza infection documented as the principal diagnosis using International Classification of Diseases codes and non-exposure as hospitalization for orthopedic surgery. Logistic regression was used to analyze the risk of subsequent hospitalization for AMI within 12 months following the exposure.

Results

Among 30,657 middle-aged adults with an indexed hospitalization, 8,840 (28.8%) had an influenza-associated hospitalization. 81 (0.92%) were subsequently rehospitalized with AMI within 12 months after the indexed hospitalization. Compared with the control group, the risk of subsequent hospitalization for AMI was significantly increased (odds ratio [OR]: 2.54, 95% confidence interval [CI]: 1.64–3.92, p<0.001). The association remained significant even after adjusting for potential confounders (adjusted OR: 1.81, 95% CI: 1.11–2.95, p = 0.02). Patients with a history of hypertension, but not those with diabetes mellitus, dyslipidemia or atrial fibrillation/flutter, were at increased risk (adjusted OR: 5.01, 95% CI: 2.93–8.56, p<0.001).

Conclusion

Subsequent hospitalization for AMI within 12 months following an indexed respiratory hospitalization for severe influenza increased nearly two-fold compared with the non-cardiopulmonary, non-exposure control. Recommendation of influenza vaccination extending to middle-aged adult population may be justified for the small but significant increased near-term risk of AMI.

Cardioprotective effects of Influenza Vaccination among Patients with Established Cardiovascular Disease or at High Cardiovascular Risk: A Systematic Review and Meta-analysis

BACKGROUND

The clinical impact of the influenza vaccination on cardiovascular outcomes in people with established cardiovascular disease (CVD) is still debated.

AIM

The aim of this meta-analysis was to estimate the effect of influenza vaccination on cardiovascular and cerebrovascular outcomes among patients with established CVD.

METHODS

We systematically searched all electronic databases from inception until 15 April 2022. Primary clinical outcomes were all-cause mortality (ACM), and major adverse clinical events (MACE). Secondary endpoints were heart failure, myocardial infarction, CV mortality, and stroke.

RESULTS

Eighteen articles (five randomized trials and thirteen observational studies), with a total of 22,532,165 patients were included in the analysis. There were 217,072 participants included in the high cardiovascular risk or established CVD population (vaccinated n = 111,073 and unvaccinated n = 105,999). The mean age of the patients was 68 years old, without any difference between groups (69 vs 71) years. At mean follow-up of 1.5 years, vaccinated group was associated with lower risk for all-cause mortality [HR, 0.71(95%CI, 0.63-0.80), p < 0.001], MACE [HR, 0.83(95%CI:0.72-0.96), p = 0.01], CV mortality [HR, 0.78(95%CI:0.68-0.90), p < 0.001] and myocardial infarction [HR, 0.82(95%CI:0.74-0.92), p < 0.001] compared to unvaccinated group. While incidence of stroke [HR, 1.03 (95%CI, 0.92-1.06), p = 0.61] and heart failure [HR, 0.74 (95%CI, 0.51-1.08), p = 0.12] did not differ between the two groups.

CONCLUSION

Influenza vaccination reduced major adverse clinical events, all-cause mortality, CV mortality and myocardial infarction. These highlighted the importance of influenza vaccination in established CVD or high cardiovascular risk.

[Trend analysis of influenza vaccination among hospitalized elderly people in Beijing, 2013-2019]

OBJECTIVE

To analyze the influenza vaccination trend of hospitalized elderly people (≥ 60 years old) in Beijing from 2013 to 2019.

METHODS

The influenza vaccination status and hospitalization information of elderly people were extracted from the Beijing Elderly Influenza Vaccination database (2013-2019) and the Beijing Urban Employee Basic Medical Insurance database (2013-2019), se-parately. The influenza vaccine coverage rates and annual percentage change were calculated to compare the vaccination trends of elderly people hospitalized due to different diseases. The subjects in 2018-2019 influenza season were divided into different groups according to demographic status, health conditions and hospitalization outcomes to describe and compare the distribution of influenza vaccination rates.

RESULTS

The influenza vaccine coverage rates among the elderly people hospitalized due to cardiovascular diseases, cerebrovascular diseases, respiratory diseases or diabetes mellitus were 14.6%, 13.4%, 13.4% and 11.8%, respectively. The influenza vaccination rate among those hospitalized for cardiovascular diseases remained the highest across six influenza seasons and those hospitalized for diabetes mellitus remained the lowest. The largest annual decline of influenza vaccine coverage rate was observed among the hospitalized elderly due to diabetes mellitus (-7.85%). The distribution of vaccinated population was significantly associated with age, gender, hospitalization outcome and comorbidities among the hospitalized elderly people with specific diseases in 2018-2019. Among the elderly people hospitalized due to four different diseases, the vaccination rate of the patients aged 70-79 years was higher than that of the other age groups and that of the patients aged 60-69 years was the lowest. Among the elderly people hospitalized due to respiratory diseases, the vaccination rate of men was higher than that of women, while the situation reversed among the elderly people hospitalized due to cardiovascular diseases and diabetes mellitus. Vaccination rates decreased among the older adults with poor hospitalization outcomes. Among the elderly people hospitalized due to diabetes mellitus, those with 0 comorbidity had the lowest vaccination rate (7.9%).

CONCLUSION

The trend of influenza vaccine coverage rates among the elderly people in Beijing from 2013 to 2019 was downward. We should pay more attention to influenza vaccination in elderly people with diabetes mellitus and aged 60-69 years, and carry out more research on the protective effects of influenza vaccine to promote influenza vaccine coverage among people with chronic diseases.

Doenças crônicas em idosos e vacinação contra a influenza

Introdução: As informações sobre a presença de doenças crônicas nos idosos não são registradas durante as campanhas de vacinação contra influenza, o que dificulta sua identificação (proporção) nos idosos vacinados. Objetivo: Descrever a prevalência de doenças crônicas autorreferidas em idosos vacinados contra a influenza; verificar a influência da mídia na decisão de tomar a vacina; e se recebeu orientações sobre a importância dela, segundo o tipo de profissional de saúde. Métodos: Estudo transversal descritivo, com dados coletados por meio de entrevistas com idosos vacinados contra influenza (n=798) em um Centro de Saúde de Campinas (SP) em 2019. Resultados: Na amostra estudada, a maioria eram mulheres (58,0%), indivíduos com ensino médio completo ou ensino superior (53,0%) e com plano de saúde (72,3%). As doenças mais prevalentes foram hipertensão arterial (56,9%; intervalo de confiança — IC95% 53,4–60,3), diabetes (24,7%; IC95% 21,8–27,8), doenças cardíacas (13,6%; IC95% 11,4–16,2) e respiratórias (5,6%; IC95% 4,2–7,5). A maioria (58,0%) considerou que a mídia influenciou sua decisão de tomar a vacina. Receberam orientações sobre a importância da vacinação 21,1% dos idosos, fornecidas principalmente por médicos/as (67,4%), enfermeiros/as (18,2%) e agentes de saúde (7,0%). Conclusões: A investigação mostrou que as principais doenças referidas pelos idosos vacinados foram hipertensão arterial, diabetes, cardiopatias e doenças respiratórias. A orientação de profissionais da saúde foi pouco relatada pelos idosos e a maioria referiu influência da mídia na decisão de vacinar-se. Ressaltam-se a necessidade e a relevância de investir em estratégias de comunicação em saúde, a fim de esclarecer a população sobre a importância da vacinação contra a influenza para as pessoas idosas e com doenças crônicas.

Influenza vaccine improves cardiovascular outcomes in patients with coronary artery disease: A systematic review and meta-analysis

BACKGROUND

There are inconsistent data on the clinical benefit of the influenza vaccine on cardiovascular outcomes in patients with coronary artery disease (CAD). Therefore, the aim of our study was to evaluate the effect of the influenza vaccine on cardiovascular outcomes in CAD patients.

METHODS

We searched four electronic databases from inception to September 21, 2021. Randomized controlled trials (RCTs) assessing the efficacy of influenza vaccine in CAD patients were included. The primary outcome was major adverse cardiovascular events (MACE) and secondary outcomes were all-cause mortality, cardiovascular mortality, and myocardial infarction. The risk of bias was assessed using the Cochrane Risk of Bias 2.0 tool. Effect sizes were expressed as risk ratio (RR) with its 95% confidence interval (CI). All meta-analyses were performed using a random-effects model.

RESULTS

Five RCTs involving 4211 patients were included. The mean age ranged from 54.5 to 67 years and 75% of patients were men. Influenza vaccine significantly reduced the risk of MACE (RR, 0.63; 95% CI, 0.51-0.77), all-cause mortality (RR, 058; 95% CI, 0.4-0.84) and cardiovascular mortality (RR, 0.53; 95% CI, 0.38-0.74) compared to control group. The risk of myocardial infarction was similar between both groups (RR, 0.69; 95% CI, 0.47-1.02). The certainty of the evidence was low for MACE, all-cause mortality, and cardiovascular mortality and was very low for myocardial infarction.

CONCLUSIONS

Our review shows that the influenza vaccine may reduce cardiovascular events in CAD patients. Therefore, we suggest that it be actively applied as part of secondary prevention in this population.