Influenza vaccine as a coronary intervention for prevention of myocardial infarction

The impact of influenza vaccination on cardiovascular disease

Influenza infection has been identified as a triggering or exacerbating factor for cardiovascular events. To analyse the effect of influenza vaccination on cardiovascular disease, a systematic search of studies published between 2009-2019 was conducted. All the studies that evaluated the effect of vaccination against influenza on cardiovascular events and their outcome were considered. Finally, 30 of the 1147 identified studies were included. These studies show a protective effect of the influenza vaccine on the development of cardiovascular events (myocardial infarction, cerebrovascular accidents, atrial fibrillation, and heart failure) and on the worsening of these conditions. Furthermore, the data showed that vaccinated patients have a lower risk of death from cardiovascular pathologies. Influenza vaccination is therefore an effective measure in the prevention of cardiovascular diseases both in patients with established cardiovascular disease and in the population without previous coronary pathology.

Human influenza A virus causes myocardial and cardiac-specific conduction system infections associated with early inflammation and premature death

AIMS

Human influenza A virus (hIAV) infection is associated with important cardiovascular complications, although cardiac infection pathophysiology is poorly understood. We aimed to study the ability of hIAV of different pathogenicity to infect the mouse heart, and establish the relationship between the infective capacity and the associated in vivo, cellular and molecular alterations.

METHODS AND RESULTS

We evaluated lung and heart viral titres in mice infected with either one of several hIAV strains inoculated intranasally. 3D reconstructions of infected cardiac tissue were used to identify viral proteins inside mouse cardiomyocytes, Purkinje cells, and cardiac vessels. Viral replication was measured in mouse cultured cardiomyocytes. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were used to confirm infection and study underlying molecular alterations associated with the in vivo electrophysiological phenotype. Pathogenic and attenuated hIAV strains infected and replicated in cardiomyocytes, Purkinje cells, and hiPSC-CMs. The infection was also present in cardiac endothelial cells. Remarkably, lung viral titres did not statistically correlate with viral titres in the mouse heart. The highly pathogenic human recombinant virus PAmut showed faster replication, higher level of inflammatory cytokines in cardiac tissue and higher viral titres in cardiac HL-1 mouse cells and hiPSC-CMs compared with PB2mut-attenuated virus. Correspondingly, cardiac conduction alterations were especially pronounced in PAmut-infected mice, associated with high mortality rates, compared with PB2mut-infected animals. Consistently, connexin43 and NaV1.5 expression decreased acutely in hiPSC-CMs infected with PAmut virus. YEM1L protease also decreased more rapidly and to lower levels in PAmut-infected hiPSC-CMs compared with PB2mut-infected cells, consistent with mitochondrial dysfunction. Human IAV infection did not increase myocardial fibrosis at 4-day post-infection, although PAmut-infected mice showed an early increase in mRNAs expression of lysyl oxidase.

CONCLUSION

Human IAV can infect the heart and cardiac-specific conduction system, which may contribute to cardiac complications and premature death.

Influenza and Pneumococcal Vaccination in Non-Infected Cardiometabolic Patients from the Americas during the COVID-19 Pandemic. A Sub-Analysis of the CorCOVID-LATAM Study

BACKGROUND

Influenza vaccination (IV) and Pneumococcus vaccination (PV) are recommended for patients with cardiometabolic diseases. This study aimed to evaluate the immunization rate of ambulatory cardiometabolic patients during the COVID-19 pandemic in the Americas.

METHODS

Electronic surveys were collected from 13 Spanish speaking countries between 15 June and 15 July 2020.

RESULTS

4216 patients were analyzed. Mean age 60 (±15) years and 49% females. Global IV rate was 46.5% and PV 24.6%. Vaccinated patients were older (IV = 63 vs. 58 years; PV = 68 vs. 59, p < 0.01) but without gender difference. Vaccination rates were greater in higher-risk groups (65+, diabetics, heart failure), but not in coronary artery disease patients. In the Southern cone, the rate of IV and PV was approximately double that in the tropical regions of the Americas. In a multivariate model, geographic zone (IV = OR 2.02, PV = OR 2.42, p < 0.001), age (IV = OR 1.023, PV = OR 1.035, p < 0.001), and incomes (IV = OR 1.28, PV = OR 1.58, p < 0.001) were predictors for vaccination.

CONCLUSIONS

During the COVID-19 pandemic, ambulatory patients with cardiometabolic diseases from the Americas with no evidence of COVID-19 infection had lower-than-expected rates of IV and PV. Geographic, social, and cultural differences were found, and they should be explored in depth.

Quantifying the Impact of Influenza Among Persons With Type 2 Diabetes Mellitus: A New Approach to Determine Medical and Physical Activity Impact

BACKGROUND

We describe the impact of influenza on medical outcomes and daily activities among people with and without type 2 diabetes mellitus (T2DM).

METHODS

Retrospective cohort analysis of a US health plan offering a digital wellness platform connecting wearable devices capable of tracking steps, sleep, and heart rate. For the 2016 to 2017 influenza season, we compared adults with T2DM to age and gender matched controls. Medical claims were used to define cohorts and identify influenza events and outcomes. Digital tracking data were aggregated at time slices of minute-, day-, week-, and year-level. A pre-post study design compared the peri-influenza period (two weeks before and four weeks after influenza diagnosis) to the six-week preceding period (baseline).

RESULTS

A total of 54 656 T2DM and 113 016 non-DM controls were used for the study. People with T2DM had more influenza claims, vaccinations, and influenza antivirals per 100 people (1.96% vs 1.37%, 34.3% vs 24.3%, and 27.1 vs 22 respectively, P < .001). A total of 1086 persons with T2DM and 1567 controls had an influenza claim (47.4% male, median age 54, 6.4% vs 7.8% trackers, respectively). Glycemic events, pneumonia, and ischemic heart disease increased over baseline during the peri-influenza period for T2DM (1.74-, 7.4-, and 1.6-fold increase respectively, P < .01). In a device wearing subcohort, we observed 10 000 fewer steps surrounding the influenza event, with the lowest (5500 steps) two days postinfluenza. Average heart rate increased significantly (+5.5 beats per minute) one day prior to influenza.

CONCLUSION

Influenza increases rates of pneumonia, heart disease, and abnormal glucose levels among people with T2DM, and negatively impacts daily activities compared to controls.

Electrocardiography in Early Diagnosis of Cardiovascular Complications of COVID-19; a Systematic Literature Review

INTRODUCTION

Many reports have stated that patients admitted for COVID-19 may also suffer from cardiovascular diseases, suggesting cardiovascular involvement in COVID-19. Since there is direct association between electrocardiography (ECG) data and the prognosis of cardiovascular disease, a systematic literature review was performed in the present study to address this association and make a conclusive agreement on the early diagnostic and prognostic values of ECG in patients with COVID-19.

METHODS

Electronic databases including PubMed, Scopus, Web of Science, Science Direct, Ovid, Embase, and Google Scholar were searched for "COVID-19" and "ECG" using all their equivalents and similar terms as search words. Afterwards, the records were limited to English articles and irrelevant documents, as well as articles that reported drug-induced cardiac dysfunction or patients with previous history of cardiovascular complications were excluded.

RESULTS

Overall, 31 articles with 2379 patients were found and used for qualitative data extraction. Findings showed that there is a significant association between COVID-19 infection and ECG findings. Also, ST-segment changes, T wave inversions, QT prolongation, and atrial fibrillation were found to be early indicators of cardiac involvement of COVID-19, which were associated with worse outcomes.

CONCLUSION

It is recommended to use ECG as a valuable diagnostic and prognostic tool for cardiac evaluation of patients with COVID-19.

Electrocardiography in Early Diagnosis of Cardiovascular Complications of COVID-19; a Systematic Literature Review

INTRODUCTION

Many reports have stated that patients admitted for COVID-19 may also suffer from cardiovascular diseases, suggesting cardiovascular involvement in COVID-19. Since there is direct association between electrocardiography (ECG) data and the prognosis of cardiovascular disease, a systematic literature review was performed in the present study to address this association and make a conclusive agreement on the early diagnostic and prognostic values of ECG in patients with COVID-19.

METHODS

Electronic databases including PubMed, Scopus, Web of Science, Science Direct, Ovid, Embase, and Google Scholar were searched for "COVID-19" and "ECG" using all their equivalents and similar terms as search words. Afterwards, the records were limited to English articles and irrelevant documents, as well as articles that reported drug-induced cardiac dysfunction or patients with previous history of cardiovascular complications were excluded.

RESULTS

Overall, 31 articles with 2379 patients were found and used for qualitative data extraction. Findings showed that there is a significant association between COVID-19 infection and ECG findings. Also, ST-segment changes, T wave inversions, QT prolongation, and atrial fibrillation were found to be early indicators of cardiac involvement of COVID-19, which were associated with worse outcomes.

CONCLUSION

It is recommended to use ECG as a valuable diagnostic and prognostic tool for cardiac evaluation of patients with COVID-19.

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

Cardiovascular diseases (CVDs) are among the leading causes of mortality and morbidity worldwide. There are many contrasting ideas on the effectiveness of influenza vaccination on CVDs. This study aimed to investigate the association between influenza vaccination and the risk of CVDs. We systematically searched all PubMed/Medline, EMBASE, and the Cochrane library entries up to November 2019 for studies of influenza vs. the CVDs outcomes. We conducted a random-effects meta‐analysis using the inverse variance method for pooled risk ratios (RR) or odds ratios (OR) and evaluated statistical heterogeneity using the I² statistic. We identified 17 studies (6 randomized controlled trial [RCT], 5 cohorts, and 6 case–control) with a total of 180,043 cases and 276,898 control participants. The pooled RR of developing CVDs after influenza vaccination in RCT studies was 0.55 (95% CI 0.41–0.73), which was significant (P-value = 0.00). The pooled OR of decreasing CVDs after influenza vaccination in cohort studies was 0.89 (95% CI 0.77–1.04). The pooled OR of developing CVDs after influenza vaccination by pooling case–control studies was 0.70 (95% CI 0.57–0.86, (P-value = 0.00). All of these studies suggest decreased risks of CVDs with influenza vaccination. The current study does support the protective role of influenza vaccination on CVDs events. Health authorities may develop evidence-based preventive strategies to offer influenza vaccination in patients with CVDs.

Association of influenza infection and vaccination with cardiac biomarkers and left ventricular ejection fraction in patients with acute myocardial infarction

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We examined the association of influenza infection and vaccination with cardiac biomarkers and LVEF .

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Mean and median CK-MB levels were significantly higher among unvaccinated cases .

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Large size infarcts were more frequent in influenza positive cases and less frequent in vaccinated cases.

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Influenza vaccine may have a protective effect against large infarcts .

Aims

The aim of this study was to examine the association of influenza infection and vaccination with extent of cardiac damage during acute myocardial infarctions (AMIs) as measured by serum biomarkers and left ventricular ejection function (LVEF) in patients.

Methods

Post-hoc analysis was performed on data from a prospective case-control study of influenza and AMI, conducted in a tertiary care hospital in Sydney, Australia. We included 275 cases of AMI, aged ≥ 40 years admitted to the cardiology during the study period.

Results

Mean and median CK-MB levels were significantly higher among unvaccinated group compared to vaccinated group (p value < 0.05). Troponin levels were also higher among unvaccinated group compared to vaccinated group; although not statistically significant. Troponin and CKMB values were not statistically different among influenza positive cases and influenza negative cases. Large size infarcts were less frequent among vaccinated cases compared to unvaccinated cases (25% vs 35.5%) and were more frequent among influenza positive cases compared to influenza negative cases (35.3% vs 31.5%), however differences were not statistically significant. LVEF was lower among vaccinated cases compared to unvaccinated cases (62.5% vs. 52.8%) and influenza positive cases compared to influenza negative cases (58.8% vs 55.4), however differences were not significant.

Conclusion

Lower CKMB levels among vaccinated groups showed that influenza vaccine may have a protective effect against large infarcts, therefore influenza vaccination should be recommended for high risk groups. The study suggests an association of larger infarcts with influenza infection, but larger studies are required to confirm this.

Influenza coverage rates in subjects with chronic heart diseases: results obtained in four consecutive immunisation seasons in the Local Health Unit of Ferrara (North Italy)"

Background

Seasonal influenza epidemics yearly affects 5–15% of the world’s population, resulting in 3–5 million serious cases and up to 650,000 deaths. According to the 2017–2019 Italian National Immunisation Plan, free immunisation is offered to the categories at increased risk of experience the complications of the infection (over 65 years old subjects, pregnant women and individuals with underlying conditions, including chronic heart diseases). Rising evidence suggests that influenza can trigger adverse cardiovascular events therefore the vaccination is recommended for secondary prevention of cardiovascular diseases. Despite this, the influenza coverage rate in subjects with chronic heart disease is underestimated.

Methods

The study investigated the coverage rate in four consecutive influenza seasons (from 2011/2012 to 2014/2015) in subjects that benefit from exemption from paying healthcare costs for chronic heart disease living in Local Health Unit (LHU) of Ferrara (Italy), comparing the databases of exemptions and immunisations.

Results

The levels of influenza vaccine uptake were unstable, reaching the 50.3% in 2011/2012 immunisation season and falling to 42.2% in the following year. Coverage rates increased with increasing age, without achieving the 75% target, neither in over 65 years old subjects. The logistic regression analysis showed that influenza coverage rates were statistically significant different (p < 0.0001, 0.003 only for category of disease in 2011/2012 immunisation season) according to age, district of residence, category of chronic heart disease and length of exemption, but not influenced by gender.

Conclusions

The recommendation of influenza immunisation was weakly followed in individuals with chronic heart diseases. A collaboration between cardiologists, GPs, scientific societies and patient associations could successfully support influenza vaccine uptake.

Immune Mechanisms in Cardiovascular Diseases Associated With Viral Infection

Influenza virus infection causes 3-5 million cases of severe illness and 250,000-500,000 deaths worldwide annually. Although pneumonia is the most common complication associated with influenza, there are several reports demonstrating increased risk for cardiovascular diseases. Several clinical case reports, as well as both prospective and retrospective studies, have shown that influenza can trigger cardiovascular events including myocardial infarction (MI), myocarditis, ventricular arrhythmia, and heart failure. A recent study has demonstrated that influenza-infected patients are at highest risk of having MI during the first seven days of diagnosis. Influenza virus infection induces a variety of pro-inflammatory cytokines and chemokines and recruitment of immune cells as part of the host immune response. Understanding the cellular and molecular mechanisms involved in influenza-associated cardiovascular diseases will help to improve treatment plans. This review discusses the direct and indirect effects of influenza virus infection on triggering cardiovascular events. Further, we discussed the similarities and differences in epidemiological and pathogenic mechanisms involved in cardiovascular events associated with coronavirus disease 2019 (COVID-19) compared to influenza infection.

Acute Cardiovascular Events Associated With Influenza in Hospitalized Adults : A Cross-sectional Study

BACKGROUND

Influenza may contribute to the burden of acute cardiovascular events during annual influenza epidemics.

OBJECTIVE

To examine acute cardiovascular events and determine risk factors for acute heart failure (aHF) and acute ischemic heart disease (aIHD) in adults with a hospitalization associated with laboratory-confirmed influenza.

DESIGN

Cross-sectional study.

SETTING

U.S. Influenza Hospitalization Surveillance Network during the 2010-to-2011 through 2017-to-2018 influenza seasons.

PARTICIPANTS

Adults hospitalized with laboratory-confirmed influenza and identified through influenza testing ordered by a practitioner.

MEASUREMENTS

Acute cardiovascular events were ascertained using discharge codes from the International Classification of Diseases (ICD), Ninth Revision, Clinical Modification, and ICD, 10th Revision. Age, sex, race/ethnicity, tobacco use, chronic conditions, influenza vaccination, influenza antiviral medication, and influenza type or subtype were included as exposures in logistic regression models, and marginal adjusted risk ratios and 95% CIs were estimated to describe factors associated with aHF or aIHD.

RESULTS

Among 89 999 adults with laboratory-confirmed influenza, 80 261 had complete medical record abstractions and available ICD codes (median age, 69 years [interquartile range, 54 to 81 years]) and 11.7% had an acute cardiovascular event. The most common such events (non-mutually exclusive) were aHF (6.2%) and aIHD (5.7%). Older age, tobacco use, underlying cardiovascular disease, diabetes, and renal disease were significantly associated with higher risk for aHF and aIHD in adults hospitalized with laboratory-confirmed influenza.

LIMITATION

Underdetection of cases was likely because influenza testing was based on practitioner orders. Acute cardiovascular events were identified by ICD discharge codes and may be subject to misclassification bias.

CONCLUSION

In this population-based study of adults hospitalized with influenza, almost 12% of patients had an acute cardiovascular event. Clinicians should ensure high rates of influenza vaccination, especially in those with underlying chronic conditions, to protect against acute cardiovascular events associated with influenza.

PRIMARY FUNDING SOURCE

Centers for Disease Control and Prevention.

Influenza Vaccination to Reduce Cardiovascular Morbidity and Mortality in Patients With COVID-19: JACC State-of-the-Art Review

Viral respiratory infections are risk factors for cardiovascular disease (CVD). Underlying CVD is also associated with an increased risk of complications following viral respiratory infections, including increased morbidity, mortality, and health care utilization. Globally, these phenomena are observed with seasonal influenza and with the current coronavirus disease 2019 (COVID-19) pandemic. Persons with CVD represent an important target population for respiratory virus vaccines, with capacity developed within 3 large ongoing influenza vaccine cardiovascular outcomes trials to determine the potential cardioprotective effects of influenza vaccines. In the context of COVID-19, these international trial networks may be uniquely positioned to redeploy infrastructure to study therapies for primary and secondary prevention of COVID-19. Here, we describe mechanistic links between influenza and COVID-19 infection and the risk of acute cardiovascular events, summarize the data to date on the potential cardioprotective effects of influenza vaccines, and describe the ongoing influenza vaccine cardiovascular outcomes trials, highlighting important lessons learned that are applicable to COVID-19.

The disease burden of influenza beyond respiratory illness

Although influenza is primarily considered a respiratory infection and causes significant respiratory mortality, evidence suggests that influenza has an additional burden due to broader consequences of the illness. Some of these broader consequences include cardiovascular events, exacerbations of chronic underlying conditions, increased susceptibility to secondary bacterial infections, functional decline, and poor pregnancy outcomes, all of which may lead to an increased risk for hospitalization and death. Although it is methodologically difficult to measure these impacts, epidemiological and interventional study designs have evolved over recent decades to better take them into account. Recognizing these broader consequences of influenza virus infection is essential to determine the full burden of influenza among different subpopulations and the value of preventive approaches. In this review, we outline the main influenza complications and societal impacts beyond the classical respiratory symptoms of the disease.

Relationship between Influenza Vaccination Coverage Rate and COVID-19 Outbreak: An Italian Ecological Study

Background: The lack of specific vaccines or drugs against coronavirus disease 2019 (COVID-19) warrants studies focusing on alternative clinical approaches to reduce the spread of this pandemic disease. In this study, we investigated whether anti-influenza vaccination plays a role in minimizing the diffusion of COVID-19 in the Italian population aged 65 and over. Methods: Four COVID-19 outcomes were used: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence, hospitalizations for COVID-19 symptoms, admissions to intensive care units for reasons related to SARS-CoV-2, and deaths attributable to COVID-19. Results: At univariate analyses, the influenza vaccination coverage rates correlated negatively with all COVID-19 outcomes (Beta ranging from -134 to -0.61; all p < 0.01). At multivariable analyses, influenza vaccination coverage rates correlated independently with SARS-CoV-2 seroprevalence (Beta (95% C.I.): -130 (-198, -62); p = 0.001), hospitalizations for COVID-19 symptoms (Beta (95% C.I.): -4.16 (-6.27, -2.05); p = 0.001), admission to intensive care units for reasons related to SARS-CoV-2 (Beta (95% C.I.): -0.58 (-1.05, -0.12); p = 0.017), and number of deaths attributable to COVID-19 (Beta (95% C.I.): -3.29 (-5.66, -0.93); p = 0.010). The R2 observed in the unadjusted analysis increased from 82% to 159% for all the considered outcomes after multivariable analyses. Conclusions: In the Italian population, the coverage rate of the influenza vaccination in people aged 65 and over is associated with a reduced spread and a less severe clinical expression of COVID-19. This finding warrants ad hoc studies to investigate the role of influenza vaccination in preventing the spread of COVID-19.

Sociodemographic Disparities in Influenza Vaccination Among Adults With Atherosclerotic Cardiovascular Disease in the United States

Importance

Atherosclerotic cardiovascular disease (ASCVD) remains a leading cause of death and disability in the US and worldwide. Influenza vaccination has shown to decrease overall morbidity, mortality, severity of infection, and hospital readmissions among these individuals. However, national estimates of influenza vaccination among individuals with ASCVD in the US are not well studied.

Objective

To evaluate the prevalence of and sociodemographic disparities in influenza vaccination among a nationally representative sample of individuals with ASCVD.

Design, Setting, and Participants

Pooled Medical Expenditure Panel Survey data from 2008 to 2016 were used and included adults 40 years or older with ASCVD. Participants' ASCVD status was ascertained via self-report and/or International Classification of Diseases, Ninth Revision diagnosis of coronary heart disease, peripheral artery disease, and/or cerebrovascular disease. Analysis began April 2020.

Main Outcomes and Measures

Prevalence and characteristics of adults with ASCVD who lacked influenza vaccination during the past year. Covariates including age, sex, race/ethnicity, family income, insurance status, education level, and usual source of care were assessed.

Results

Of 131 881 adults, 19 793 (15.7%) had ASCVD, corresponding to 22.8 million US adults annually. A total of 7028 adults with ASCVD (32.7%), representing 7.4 million adults, lacked influenza vaccination. The highest odds of lacking vaccination were observed among individuals aged 40 to 64 years (odds ratio [OR], 2.32; 95% CI, 2.06-2.62), without a usual source of care (OR, 2.00; 95% CI, 1.71-2.33), without insurance (OR, 2.05; 95% CI, 1.63-2.58), with a lower education level (OR, 1. 25; 95% CI, 1.12-1.40), with a lower income level (OR, 1.14; 95% CI, 1.01-1.27), and of non-Hispanic Black race/ethnicity (OR, 1.24, 95% CI, 1.10-1.41). A stepwise increase was found in the prevalence and odds of lacking influenza vaccination among individuals with increase in high-risk characteristics. Overall, 1171 individuals (59.7%; 95% CI, 55.8%-63.5%) with 4 or more high-risk characteristics and ASCVD (representing 732 524 US adults annually) reported lack of influenza vaccination (OR, 6.06; 95% CI, 4.88-7.53).

Conclusion and Relevance

Despite current recommendations, a large proportion of US adults with established ASCVD lack influenza vaccination, with several sociodemographic subgroups having greater risk. Focused public health initiatives are needed to increase access to influenza vaccinations for high-risk and underserved populations.

Acute Coronary Syndromes and Covid-19: Exploring the Uncertainties

Since an association between myocardial infarction (MI) and respiratory infections has been described for influenza viruses and other respiratory viral agents, understanding possible physiopathological links between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and acute coronary syndromes (ACS) is of the greatest importance. The initial data suggest an underestimation of ACS cases all over the world, but acute MI still represents a major cause of morbidity and mortality worldwide and should not be overshadowed during the coronavirus disease (Covid-19) pandemic. No common consensus regarding the most adequate healthcare management policy for ACS is currently available. Indeed, important differences have been reported between the measures employed to treat ACS in China during the first disease outbreak and what currently represents clinical practice across Europe and the USA. This review aims to discuss the pathophysiological links between MI, respiratory infections, and Covid-19; epidemiological data related to ACS at the time of the Covid-19 pandemic; and learnings that have emerged so far from several catheterization labs and coronary care units all over the world, in order to shed some light on the current strategies for optimal management of ACS patients with confirmed or suspected SARS-CoV-2 infection.

Causal relationship between influenza infection and risk of acute myocardial infarction: pathophysiological hypothesis and clinical implications

Presently several evidences support an association between acute myocardial infarction and influenza infection. The pathophysiology rationale rests on the release of inflammation cytokines, rupture of atherosclerotic plaque, and triggering of prothrombotic events leading to coronary artery occlusion. Several observational evidences support a potential role of influenza vaccine in cardiovascular prevention. It is estimated that the efficacy of influenza vaccine in preventing myocardial infarction could range between 15% and 45%. Notwithstanding the clear recommendation of numerous guidelines concerning patients with cardiovascular diseases, vaccination rates are still low in the high-risk groups. Influenza vaccine as preventive measure of cardiovascular disease still awaits support from randomized clinical trials. Nonetheless, considering the favourable cost-efficacy and safety profile of influenza vaccination, its use should be encouraged in everyday clinical practice.

Cardiovascular Considerations in Treating Patients With Coronavirus Disease 2019 (COVID-19)

A novel betacoronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread rapidly across the globe since December 2019. Coronavirus disease 2019 (COVID-19) has a significantly higher mortality rate than seasonal influenza and has disproportionately affected older adults, especially those with cardiovascular disease and related risk factors. Adverse cardiovascular sequelae, such as myocarditis, acute myocardial infarction, and heart failure, have been reported in patients with COVID-19. No established treatment is currently available; however, several therapies, including remdesivir, hydroxychloroquine and chloroquine, and interleukin (IL)-6 inhibitors, are being used off-label and evaluated in ongoing clinical trials. Considering these therapies are not familiar to cardiovascular clinicians managing these patients, this review describes the pharmacology of these therapies in the context of their use in patients with cardiovascular-related conditions.

Glycaemic control, antidiabetic medications and influenza vaccination coverage among patients with diabetes in Udine, Italy

Objective

The objectives of this study were to estimate influenza vaccination coverage among patients with diabetes mellitus in an Italian 250 000-inhabitant area in the 2017-2018 season and to assess whether glycaemic control and pharmacological treatment were associated with the likelihood of being vaccinated.

Design

In this cross-sectional study, we analysed anonymous health administrative databases, linked with each other at the individual patient level through a stochastic key: diabetes mellitus registry, vaccinations, drug prescriptions and laboratory database.

Setting

The study was conducted in the catchment area of the University Hospital of Udine ('the Udine area'), a 250 000-inhabitant area in the northeast of Italy.

Participants

The study included all subjects included in the regional registry of patients with diabetes mellitus, living in the Udine area as of 1 October 2017.

Main outcome measures

Vaccination coverage in the 2017-2018 influenza season was calculated. The association between patients' characteristics and the likelihood of being vaccinated was assessed through multivariate log binomial regression.

Result

53.0% of 15 900 patients with diabetes living in the area were vaccinated. Coverage increased with age, approaching 75% at ≥85 years. Patients lacking recent glycated haemoglobin testing were less likely to be vaccinated (43.4% vaccination coverage), as were those not treated pharmacologically (44.4% vaccination coverage). Patients treated with both insulin, metformin and other antidiabetic medications were more likely to be vaccinated than those treated with metformin alone (58.1% vaccination coverage; adjusted relative risk=1.07, 95% CI 1.01 to 1.14).

Conclusion

Influenza vaccination coverage was suboptimal in this Italian population of patients with diabetes. Strategies to improve diabetes management could in turn positively affect influenza coverage.

Seasonality of ventricular fibrillation at first myocardial infarction and association with viral exposure

AIMS

To investigate seasonality and association of increased enterovirus and influenza activity in the community with ventricular fibrillation (VF) risk during first ST-elevation myocardial infarction (STEMI).

METHODS

This study comprised all consecutive patients with first STEMI (n = 4,659; aged 18-80 years) admitted to the invasive catheterization laboratory between 2010-2016, at Copenhagen University Hospital, Rigshospitalet, covering eastern Denmark (2.6 million inhabitants, 45% of the Danish population). Hospital admission, prescription, and vital status data were assessed using Danish nationwide registries. We utilized monthly/weekly surveillance data for enterovirus and influenza from the Danish National Microbiology Database (2010-2016) that receives copies of laboratory tests from all Danish departments of clinical microbiology.

RESULTS

Of the 4,659 consecutively enrolled STEMI patients, 581 (12%) had VF before primary percutaneous coronary intervention. In a subset (n = 807), we found that VF patients experienced more generalized fatigue and flu-like symptoms within 7 days before STEMI compared with the patients without VF (OR 3.39, 95% CI 1.76-6.54). During the study period, 2,704 individuals were diagnosed with enterovirus and 19,742 with influenza. No significant association between enterovirus and VF (OR 1.00, 95% CI 0.99-1.02), influenza and VF (OR 1.00, 95% CI 1.00-1.00), or week number and VF (p-value 0.94 for enterovirus and 0.89 for influenza) was found.

CONCLUSION

We found no clear seasonality of VF during first STEMI. Even though VF patients had experienced more generalized fatigue and flu-like symptoms within 7 days before STEMI compared with patients without VF, no relationship was found between enterovirus or influenza exposure and occurrence of VF.

Prevalence and associated factors of influenza vaccination coverage in Korean adults with cardiovascular disease

Infection with influenza virus increases morbidity and mortality in patients with risk factors, including cardiovascular disease (CVD). This study aimed to evaluate factors associated with influenza vaccination coverage in Korean CVD patients.We included 19,599 adults from the 2010 to 2012 Korea National Health and Nutrition Examination Survey. Influenza vaccination rates were compared in subjects with and without CVD. Logistic regression analysis was performed to identify factors associated with influenza vaccination in Korean adults with CVD before and after stratification for age (<65 and ≥65 years).Significantly higher vaccination rates were observed in individuals with CVD than in those without CVD (61.4% vs 31.0%, P < .001). However, young individuals (19-49 years) had decreased influenza vaccination rates, with no difference based on CVD status (20.3% vs 21.6%, P = .859). A lack of private insurance (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.23-0.98) and recent health screening (OR, 4.56; 95% CI, 1.90-10.92) were independent factors for influenza vaccination in CVD patients aged <65 years, whereas female sex (OR, 3.71; 95% CI, 1.24-11.07) and less education (OR, 4.59; 95% CI, 1.27-16.61) were independent factors in CVD patients aged ≥65 years.Improving influenza vaccination coverage for Korean adults with CVD is important, especially in young patients. For young patients with CVD, influenza vaccination status is independently associated with the presence of private insurance and recent health screening. This finding could help establish public health policies to promote influenza vaccination in this population.

Adult Immunization in Occupational Settings: A Consensus of Indian Experts

There is an increasing focus on instituting wellness programs at the workplace among organizations in India. Such programs are aimed at improving employee health, which in turn, helps in reducing absenteeism, as well as in increasing work productivity and improving employee engagement. Of note, adult vaccination plays a significant role in ensuring the well-being of employees, as well as in keeping an organization profitable. The burden of vaccine-preventable diseases (VPDs) in adults is increasing in India, causing significant morbidity and disability. Moreover, adult immunization is an underpublicized concept in India. There is an urgent need to create awareness about adult immunization in India, particularly in occupational health settings-both at the employee and employer levels. In view of this, an expert meeting was held under the aegis of the Indian Association of Occupational Health (IAOH) to discuss key issues pertaining to the burden of VPDs in the working population in India and to formulate guidelines on adult vaccination in occupational health settings. This consensus guideline document may act as a guide for organizations across India to create awareness about adult vaccination and also to design workplace vaccination programs to promote better health among employees.

Influenza vaccine and cardiac protection: a study from a tertiary care center

Patients with heart disease (HD) are at increased risk of developing cardiac complications if they acquire the influenza virus. The objective of this study was to determine whether the influenza vaccine has a primary role in preventing newly diagnosed HD in patients who have no history of HD and who were being followed up at the American University of Beirut Medical Center (AUBMC). The study is a retrospective cohort, with 2-years follow up, which was conducted using electronic medical records between the years of 2011-2013 in a tertiary care center. All patients 60 years and older (n = 698) who have taken the flu vaccine were randomly selected from the University Health Service records (UHS) and compared to a group who has not taken the flu vaccine during the same period. The odds of developing HD among vaccinated people with cofactors are 0.97 times the odds of that among non-vaccinated. This odds ratio is not significantly different than that of people vaccinated without cofactors (OR = 1.74). The occurrence of HD in the presence of vaccination revealed a non-significant decrease trend with the increase in a number of risk factors (OR = 1.61 vs 0.97). Our results suggest that there was a non-significant difference between the effect of the vaccine for influenza on patients who had cofactors for HD and those who had not. Similarly, the effect of vaccine showed a non-significant increase in protective effect as the number of comorbidities increase. The potential effects of the vaccine may be related to the protection against flu.

Outcomes of Acute Myocardial Infarction in Patients with Influenza and Other Viral Respiratory Infections

BACKGROUND

Acute influenza infection can trigger acute myocardial infarction, however, outcome of patients with acute myocardial infarction during influenza infection is largely unknown.

METHODS

Patients ≥18 years old with ST-elevation and non-ST-elevation myocardial infarction during January 2013-December 2014 were identified using the National Inpatient Sample. The clinical outcomes were compared among patients who had no respiratory infection to the ones with influenza and other viral respiratory infections using propensity score-matched analysis.

RESULTS

Of 1,884,985 admissions for acute myocardial infarction, acute influenza and other viral infections were diagnosed in 9,885 and 11,485 patients, respectively, accounting for 1.1% of patients. Acute myocardial infarction patients with concomitant influenza infection had a worse outcome than those with acute myocardial infarction alone, in terms of in-hospital case fatality rate, development of shock, acute respiratory failure, acute kidney injury, and higher rate of blood transfusion after propensity scores. The length of stay is also significantly longer in influenza patients with acute myocardial infarction, compared with patients with acute myocardial infarction alone. However, patients who developed acute myocardial infarction during other viral respiratory infection have a higher rate of acute respiratory failure but overall lower mortality rate, and are less likely to develop shock or require blood transfusion after propensity match. Despite presenting with acute myocardial infarction, less than one-fourth of patients with concomitant influenza infection underwent coronary angiography, but more than half (51.4%) required revascularization.

CONCLUSION

Influenza infection is associated with worse outcomes in acute myocardial infarction patients, and patients were less likely to receive further evaluation with invasive coronary angiography.

The challenges of influenza for public health

Influenza, an infectious disease of the respiratory system, represents a major burden for public health. This disease affects all age groups with different prognosis, being life threatening for vulnerable individuals. Despite influenza being a vaccine-preventable disease, the control of the infection needs annual vaccination campaigns and constant improvements. Herein, the main challenges of influenza in relation to the pathogenic agent, the available vaccines and the health impact identified during the Light on Vax event, an expert meeting organized by the Asociación Española de Vacunología [Spanish Vaccinology Association] (AEV), are reported. Further possible steps in the control of influenza are also suggested. Ideally, the development of innovative and universal vaccines that would confer life-lasting and broader-spectrum immunity is highly desirable.

Pathogenesis and prevention of risk of cardiovascular events in patients with pneumococcal community-acquired pneumonia

It is now well recognized that cardiovascular events (CVE) occur quite commonly, both in the acute phase and in the long-term, in patients with community-acquired pneumonia (CAP). CVE have been noted in up to 30% of patients hospitalized with all-cause CAP. One systematic review and meta-analysis of hospitalized patients with all-cause CAP noted that the incidence rates for overall cardiac events were 17.7%, for incident heart failure were 14.1%, for acute coronary syndromes were 5.3% and for incident cardiac arrhythmias were 4.7%. In the case of pneumococcal CAP, almost 20% of patients studied had one or more of these cardiac events. Recent research has provided insights into the pathogenesis of the acute cardiac events occurring in pneumococcal infections. With respect to the former, key involvements of the major pneumococcal protein virulence factor, pneumolysin, are now well documented, whilst systemic platelet-driven neutrophil activation may also contribute. However, events involved in the pathogenesis of the long-term cardiovascular sequelae remain largely unexplored. Emerging evidence suggests that persistent antigenaemia may predispose to the development of a systemic pro-inflammatory/prothrombotic phenotype underpinning the risk of future cardiovascular events. The current manuscript briefly reviews the occurrence of cardiovascular events in patients with all-cause CAP, as well as in pneumococcal and influenza infections. It highlights the close interaction between influenza and pneumococcal pneumonia. It also includes a brief discussion of mechanisms of the acute cardiac events in CAP. However, the primary focus is on the prevalence, pathogenesis and prevention of the longer-term cardiac sequelae of severe pneumococcal disease, particularly in the context of persistent antigenaemia and associated inflammation.

Health information technology use and influenza vaccine uptake among US adults

OBJECTIVE

This study aims to estimate the association between health information technology (HIT) use and influenza vaccine uptake among US adults.

MATERIALS AND METHODS

Data analysis was conducted using 2011-2015 National Health Interview Survey (NHIS) adult data (n = 169,912). HIT use was defined as having used computers (past 12 months) to seek health information, fill prescriptions, schedule appointments, communicate with health providers via email, and/or use online health chat groups. Crude and multivariable logistic regression models were used to estimate the odds of influenza vaccine uptake among HIT users versus non-users. Interactions were tested and stratified results were reported.

RESULTS

Among US adults, 39.8% received an influenza vaccine in the past 12 months, while 48.6% reported any HIT use. After adjusting for covariates, any HIT users had 1.23 times greater odds (95% CI = 1.19, 1.27) of influenza vaccine uptake relative to non-HIT users. HIT use for looking up health information on the internet (OR = 1.19, 95% CI = 1.15, 1.23), filling prescriptions (OR = 1.56; 95% CI = 1.50, 1.66), scheduling appointments (OR = 1.56; 95% CI = 1.50, 1.66), and communicating with providers via email (OR = 1.51; 95% CI = 1.44, 1.59) were significantly associated with influenza vaccine uptake.

DISCUSSION

HIT use is positively associated with influenza vaccine uptake. Each category of HIT use was independently associated with influenza vaccine uptake. To our knowledge, no other studies have evaluated the relationship between HIT use and influenza vaccine uptake. Our results are exploratory and represent an association, not a causal relationship. Longitudinal, confirmatory studies are also needed to verify our cross-sectional findings.

Infectious myocarditis: the role of the cardiac vasculature

Infectious myocarditis is the result of an immune response to a microbial infection of the heart. The blood vessels of the heart, both the intramyocardial microvasculature and the large epicardial coronary arteries, play an important role in the pathogenesis of infectious myocarditis. First of all, in addition to cardiomyocytes, endothelial cells of the cardiac (micro)vasculature are direct targets for infection. Moreover, through the expression of adhesion molecules and antigen presenting Major Histocompatibility Complex molecules, the blood vessels assist in shaping the cellular immune response in infectious myocarditis. In addition, damage and dysfunction of the cardiac (micro)vasculature are associated with thrombus formation as well as aberrant regulation of vascular tone including coronary vasospasm. These in turn can cause cardiac perfusion abnormalities and even myocardial infarction. In this review, we will discuss the role of the cardiac (micro)vasculature in the pathogenesis of infectious myocarditis.

[Mortality due to cerebrovascular disease among the elderly and vaccination against influenza: São Paulo State, Brazil, 1980-2012]

This study describes the trend of the coefficients of mortality due to cerebrovascular diseases (CbVD) among the elderly in São Paulo State, Brazil, from 1980 to 2012, before and after influenza vaccination campaigns, and identifies change points. It is an ecological, time-series study carried out with death data from the Health Ministry's Mortality Information System and population data from the Brazilian Institute of Geography and Statistics. We used linear, polynomial and joinpoint regression models in the data analysis. Between 1980 and 2012, there were 480,955 deaths due to CbVD. The mean mortality coefficients decreased for both sexes in all age groups we analyzed, with the greatest reduction in the older ages and male sex. We observed a significant reduction in the mortality trend in 1998 for male sex in the age group 60-69 years (annual percent change - APC = -3%, 95%CI: -4.3; -1.6) and for all elderly (APC = -3.8%, 95%CI: -4.4; -3.1). Considering the period as a whole, we did not observe change points for the age group 70-79 (average annual percent change - AAPC = -3.3%, 95%CI: -3.5; -3.1) and, for male sex, for the group ≥ 80 years (AAPC = -2.9%, 95%CI: -3.1; -2.6). For all elderly, the mean percentage reduction was of 3.1% per year (AAPC = -3.1%, 95%CI: -3.5; -2.7). Results show a reduction in the mortality due to CbVD in the period, with different percentage variations in coefficient reduction. The study's findings add information to the debate regarding possible effects of vaccination campaigns in reducing mortality due to CbVD among the elderly.

Extreme influenza epidemics and out-of-hospital cardiac arrest

INTRODUCTION

There is compelling evidence for an association between influenza epidemics and major adverse cardiovascular events. However, the role of extreme influenza epidemics as a trigger of out-of-hospital cardiac arrest (OHCA) is unclear. Thus, we evaluated the potential association between extreme influenza epidemics and incidence of OHCA.

METHODS

We used a quasi-experimental design with time-series analysis of national registry data for cases of OHCA from all 47 prefectures of Japan during influenza seasons between 2005 and 2014. A Poisson regression time-series model with a distributed lag non-linear model was used to estimate prefecture-specific effects of influenza epidemics on OHCA. A multivariate meta-analysis was conducted for nationally pooled estimates.

RESULTS

In total, 481,516 OHCAs of presumed cardiac origin were reported during the study period. The minimum morbidity percentile (MMP) was estimated as the 0th percentile for influenza incidence. The overall cumulative relative risk versus the MMP was 1.25 (95% confidence interval, 1.16-1.34) for extreme influenza epidemics (at the 99th percentile of influenza incidence). The effect of extreme influenza epidemics was significant for lag periods of 1.5-7.1 and 17.9-21 days. Multivariate random-effects meta-analysis indicated significant spatial heterogeneity among prefectures (Cochran Q test, p = 0.011; I² = 23.2%).

CONCLUSION

Extreme influenza epidemics are associated with higher risk of OHCA. Our findings suggest that several weeks' prevention for extreme influenza infections should be implemented to reduce the risk of OHCA.

Seasonality of the Cardiac Biomarker Troponin in the Eastern Croatian Population

Background: The seasonality of acute myocardial infarction and progressive heart failure has been well established so far. Cardiac troponins (cTns) are organ-specific, not disease-specific, biomarkers. The seasonality of cTns has not been reported before. Methods: Data were collected from the emergency admission unit of a community hospital in eastern Croatia for each month of the year 2014 covering the number of patients whose doctors requested high-sensitivity cTn I (hs-cTn I) testing, the number of positive test results and hospital admissions. Results: The proportion of patients with positive test results was 15.75% (350 patients out of 2221 patients referred to testing), with the males being outnumbered by the females (F: 57.15%, M: 42.85%) (p = 0.069). The month with the highest number of patients with positive test results was December, whereas the month with the lowest number of those patients was January (p < 0.001). The highest numbers of patients referred to testing (30.9%) and of those with positive test results (50.8%) were found in the oldest age group (76+). Conclusion: Tracking the results of cTns testing during patient admissions to emergency departments would be a more effective approach from a public health perspective than tracking the number of patients diagnosed with a particular cardiovascular (CV) disease and could be used as a research approach to guide a search for precipitating factors for CV disease specific to a local community.

Laboratory-Confirmed Respiratory Infections as Predictors of Hospital Admission for Myocardial Infarction and Stroke: Time-Series Analysis of English Data for 2004-2015

Background

Acute respiratory infections are associated with increased risk of myocardial infarction (MI) and stroke; however, the role of different organisms is poorly characterized.

Methods

Time-series analysis of English hospital admissions for MI and stroke (age-stratified: 45-64, 65-74, ≥75 years), laboratory-confirmed viral respiratory infections, and environmental data for 2004-2015. Weekly counts of admissions were modeled using multivariable Poisson regression with weekly counts of respiratory viruses (influenza, parainfluenza, rhinovirus, respiratory syncytial virus [RSV], adenovirus, or human metapneumovirus [HMPV]) investigated as predictors. We controlled for seasonality, long-term trends, and environmental factors.

Results

Weekly hospital admissions in adults aged ≥45 years averaged 1347 (interquartile range [IQR], 1217-1541) for MI and 1175 (IQR, 1023-1395) for stroke. Respiratory infections ranged from 11 cases per week (IQR, 5-53) for influenza to 55 (IQR, 7-127) for rhinovirus. In the adjusted models, all viruses except parainfluenza were significantly associated with MI and ischemic stroke admissions in those aged ≥75. Among 65- to 74-year-olds, adenovirus, rhinovirus, and RSV were associated with MI but not ischemic stroke admissions. Respiratory infections were not associated with MI or ischemic stroke in people aged 45-64 years, nor with hemorrhagic stroke in any age group. An estimated 0.4%-5.7% of MI and ischemic stroke admissions may be attributable to respiratory infection.

Conclusions

We identified small but strongly significant associations in the timing of respiratory infection (with HMPV, RSV, influenza, rhinovirus, and adenovirus) and MI or ischemic stroke hospitalizations in the elderly.

Clinical Trials Registration

NCT02984280.

Challenges in adult vaccination

Life-long primary prevention interventions beginning and continuing throughout an individual's lifetime are increasingly seen as key to meeting the global healthcare challenges that accompany demographic changes - a concept referred to as "Healthy aging". In this perspective, vaccination is seen as part of a triad, together with healthy diet and exercise. Current adult vaccine coverage is lower than target vaccination rates in most developed countries, and so vaccine preventable diseases continue to present a substantial burden on health and healthcare resources, especially in older individuals. In part, this is due to lack of knowledge and understanding of the benefits of vaccination, inconsistent recommendations by providers and uncertainties about cost benefits. However, lower vaccine effectiveness in older adults plays a part, and new vaccines with novel characteristics to improve effectiveness in older adults are required. A life-course immunization approach to ensure optimal vaccine uptake across adults of all ages can be expected to reduce morbidity and mortality in later life. To achieve this, greater emphasis on public and healthcare provider education is necessary, based on appropriate economic analyses that demonstrate the overall value of vaccination. This article introduces the technical, economic, political and demographic issues that make establishing effective adult vaccination programs such a difficult, but pressing issue, and outlines some of the steps that are now being taken to address them. Key messages Life-long preventive activities that start and continue throughout life are essential, especially as the world's population is "getting older". This "Healthy aging" approach includes not only healthy diet and physical exercise; vaccination is critical in reducing some infectious diseases and their complications. Many adults, especially older adults (who have lower immunity than younger people) develop infections such as influenza and shingles that could potentially be prevented through vaccination. This review provides a perspective on the challenges in delivering a life-course immunization program. While some vaccines are less effective in older people, newer vaccines have been developed which provide stronger and longer protection in older patients than standard existing vaccines. However, the benefits of vaccination can only be realized if the vaccines are recommended and used. For that purpose, greater education of patients and their healthcare providers is necessary. Better knowledge of vaccines and making sure that all adults are up to date with all their recommended vaccines is an essential part of "Healthy aging". This should prevent not only vaccine-preventable diseases but also reduce the risk of complications in later life.

Influenza vaccination in the elderly

Seasonal influenza is a prevalent and serious annual illness resulting in widespread morbidity and economic disruption throughout the population; the elderly and immunocompromised are particularly vulnerable to serious sequelae and mortality. The changing demographics worldwide to an aging society have important implications for public health policy and pharmaceutical innovations. For instance, primary prevention via immunization is effective in reducing the burden of influenza illness among the elderly. However, the elderly may be insufficiently protected by vaccination due to the immunosenescence which accompanies aging. In addition, vaccine hesitancy among the younger populations increases the likelihood of circulating infectious diseases, and thus concomitant exposure. While it is clear that the development of more immunogenic vaccines is an imperative and worthy endeavor, clinical trials continue to demonstrate that the current influenza vaccine formulation remains highly effective in reducing morbidity and mortality when well matched to circulating strains.

Fighting against a protean enemy: immunosenescence, vaccines, and healthy aging

The progressive increase of the aged population worldwide mandates new strategies to ensure sustained health and well-being with age. The development of better and/or new vaccines against pathogens that affect older adults is one pivotal intervention in approaching this goal. However, the functional decline of various physiological systems, including the immune system, requires novel approaches to counteract immunosenescence. Although important progress has been made in understanding the mechanisms underlying the age-related decline of the immune response to infections and vaccinations, knowledge gaps remain, both in the areas of basic and translational research. In particular, it will be important to better understand how environmental factors, such as diet, physical activity, co-morbidities, and pharmacological treatments, delay or contribute to the decline of the capability of the aging immune system to appropriately respond to infectious diseases and vaccination. Recent findings suggest that successful approaches specifically targeted to the older population can be developed, such as the high-dose and adjuvanted vaccines against seasonal influenza, the adjuvanted subunit vaccine against herpes zoster, as well as experimental interventions with immune-potentiators or immunostimulants. Learning from these first successes may pave the way to developing novel and improved vaccines for the older adults and immunocompromised. With an integrated, holistic vaccination strategy, society will offer the opportunity for an improved quality of life to the segment of the population that is going to increase most significantly in numbers and proportion over future decades.

Emergency Department demand associated with seasonal influenza, 2010 through 2014, New South Wales, Australia

Introduction

Influenza’s impact on health and health care is underestimated by influenza diagnoses recorded in health-care databases. We aimed to estimate total and non-admitted influenza-attributable hospital Emergency Department (ED) demand in New South Wales (NSW), Australia.

Methods

We used generalized additive time series models to estimate the association between weekly counts of laboratory-confirmed influenza infections and weekly rates of total and non-admitted respiratory, infection, cardiovascular and all-cause ED visits in NSW, Australia for the period 2010 through 2014. Visit categories were based on the coded ED diagnosis or the free-text presenting problem if no diagnosis was recorded.

Results

The estimated all-age, annual influenza-attributable respiratory, infection, cardiovascular and all-cause visit rates/100 000 population/year were, respectively, 120.6 (99.9% confidence interval [CI] 102.3 to 138.8), 79.7 (99.9% CI: 70.6 to 88.9), 14.0 (99.9% CI: 6.8 to 21.3) and 309.0 (99.9% CI: 208.0 to 410.1). Among respiratory visits, influenza-attributable rates were highest among < 5-year-olds and ≥ 85-year-olds. For infection and all-cause visits, rates were highest among children; cardiovascular rates did not vary significantly by age. Annual rates varied substantially by year and age group, and statistically significant associations were absent in several years or age groups. Of the respiratory visits, 73.4% did not require admission. The non-admitted proportion was higher for the other clinical categories. Around 1 in 100 total visits and more than 1 in 10 respiratory or infection visits were associated with influenza.

Discussion

Influenza is associated with a substantial and annually varying burden of hospital-attended illness in NSW.