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.

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

Importance

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

Objective

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

Design, Setting, and Participants

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

Intervention

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

Main Outcomes and Measures

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

Results

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

Conclusions and Relevance

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

Trial Registration

ClinicalTrials.gov Identifier: NCT02787044.

Influenza Vaccine Effectiveness Against All-Cause Mortality Following Laboratory-Confirmed Influenza in Older Adults, 2010-2011 to 2015-2016 Seasons in Ontario, Canada

BACKGROUND

Older adults are at increased risk of mortality from influenza infections. We estimated influenza vaccine effectiveness (VE) against mortality following laboratory-confirmed influenza.

METHODS

Using a test-negative design study and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against all-cause mortality following laboratory-confirmed influenza for community-dwelling adults aged >65 years during the 2010-2011 to 2015-2016 influenza seasons.

RESULTS

Among 54 116 older adults tested for influenza across the 6 seasons, 6837 died within 30 days of specimen collection. Thirteen percent (925 individuals) tested positive for influenza, and 50.6% were considered vaccinated for that season. Only 23.2% of influenza test-positive cases had influenza recorded as their underlying cause of death. Before and after multivariable adjustment, we estimated VE against all-cause mortality following laboratory-confirmed influenza to be 20% (95% confidence interval [CI], 8%-30%) and 20% (95% CI, 7%-30%), respectively. This estimate increased to 34% after correcting for influenza vaccination exposure misclassification. We observed significant VE against deaths following influenza confirmation during 2014-2015 (VE = 26% [95% CI, 5%-42%]). We also observed significant VE against deaths following confirmation of influenza A/H1N1 and A/H3N2, and against deaths with COPD as the underlying cause.

CONCLUSIONS

These results support the importance of influenza vaccination in older adults, who account for most influenza-associated deaths annually.

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.

Impact of the presence of heart disease, cardiovascular medications and cardiac events on outcome in COVID-19

BACKGROUND

Cardiovascular risk factors and usage of cardiovascular medication are prevalent among coronavirus disease 2019 (COVID-19) patients. Little is known about the cardiovascular implications of COVID-19. The goal herein, was to evaluate the prognostic impact of having heart disease (HD) and taking cardiovascular medications in a population diagnosed of COVID-19 who required hospitalization. Also, we studied the development of cardiovascular events during hospitalization.

METHODS

Consecutive patients with definitive diagnosis of COVID-19 made by a positive real time- -polymerase chain reaction of nasopharyngeal swabs who were admitted to the hospital from March 15 to April 14 were included in a retrospective registry. The association of HD with mortality and with mortality or respiratory failure were the primary and secondary objectives, respectively.

RESULTS

A total of 859 patients were included in the present analysis. Cardiovascular risk factors were related to death, particularly diabetes mellitus (hazard ratio in the multivariate analysis: 1.810 [1.159- -2.827], p = 0.009). A total of 113 (13.1%) patients had HD. The presence of HD identified a group of patients with higher mortality (35.4% vs. 18.2%, p < 0.001) but HD was not independently related to prognosis; renin-angiotensin-aldosterone system inhibitors, calcium channel blockers, diuretics and beta-blockers did not worsen prognosis. Statins were independently associated with decreased mortality (0.551 [0.329-0.921], p = 0.023). Cardiovascular events during hospitalization identified a group of patients with poor outcome (mortality 31.8% vs. 19.3% without cardiovascular events, p = 0.007).

CONCLUSIONS

The presence of HD is related to higher mortality. Cardiovascular medications taken before admission are not harmful, statins being protective. The development of cardiovascular events during the course of the disease is related to poor outcome.

Modelling the linkage between influenza infection and cardiovascular events via thrombosis

There is a heavy burden associated with influenza including all-cause hospitalization as well as severe cardiovascular and cardiorespiratory events. Influenza associated cardiac events have been linked to multiple biological pathways in a human host. To study the contribution of influenza virus infection to cardiovascular thrombotic events, we develop a dynamic model which incorporates some key elements of the host immune response, inflammatory response, and blood coagulation. We formulate these biological systems and integrate them into a cohesive modelling framework to show how blood clotting may be connected to influenza virus infection. With blood clot formation inside an artery resulting from influenza virus infection as the primary outcome of this integrated model, we demonstrate how blood clot severity may depend on circulating prothrombin levels. We also utilize our model to leverage clinical data to inform the threshold level of the inflammatory cytokine TNFα which initiates tissue factor induction and subsequent blood clotting. Our model provides a tool to explore how individual biological components contribute to blood clotting events in the presence of influenza infection, to identify individuals at risk of clotting based on their circulating prothrombin levels, and to guide the development of future vaccines to optimally interact with the immune system.

Diminished immune responses with aging predispose older adults to common and uncommon influenza complications

Influenza (flu) is a serious disease for older adults, with increased severity of infection and greater risk for hospitalization and death. Flu infection is limited to pulmonary epithelial cells, yet there are many systemic symptoms and older adults are more susceptible to flu-related complications. In older adults, flu rarely comes without additional complications and there is a perfect storm for enhanced disease due to multiple factors including existing co-morbidities, plus impaired lung function and dysregulated immune responses that occur with even healthy aging. Commonly, opportunistic secondary bacterial infections prosper in damaged lungs. Intensified systemic inflammation with aging can cause dysfunction in extra-pulmonary organs and tissues such as cardiovascular, musculoskeletal, neuropathologic, hepatic, and renal complications. Often overlooked is the underappreciated connections between many of these conditions, which exacerbate one another when in parallel. This review focuses on flu infection and the numerous complications in older adults associated with diminished immune responses.

Respiratory Syncytial Virus and Associations With Cardiovascular Disease in Adults

Respiratory syncytial virus (RSV) is historically known for causing respiratory illness in young children, but the appreciation of its impact on older adults is growing. Studies have shown that hospitalization for respiratory illness due to RSV is complicated by cardiovascular events in 14% to 22% of adult patients, including worsening congestive heart failure, acute coronary syndrome, and arrhythmias. Additionally, underlying cardiovascular disease is associated with hospitalization in 45% to 63% of adults with confirmed RSV. In summary, patients with cardiopulmonary disease have higher rates of health care utilization for RSV-related illness and worse outcomes. Patients with cardiovascular disease likely represent an important target population for the rapidly developing field of RSV vaccines.

Influenza vaccination and risk of hospitalization in patients with heart failure: a self-controlled case series study

Aims

Evidence supporting yearly influenza vaccination in patients with chronic heart failure (HF) is limited, consequently leading to inconsistent guideline recommendations. We aimed to investigate the impact of influenza vaccination on the risk of hospitalization in HF patients.

Methods and results

We used linked primary and secondary health records in England between 1990 and 2013. Using a self-controlled case series design with conditional Poisson regression, we estimated the incidence rate ratio (IRR, 95% CI) of the number of hospitalizations in a year following vaccination with an adjacent vaccination-free year in the same individuals. We found the uptake of vaccination to be varied and generally low (49% in 2013). Among 59,202 HF patients, influenza vaccination was associated with a lower risk of hospitalization due to cardiovascular disease (0.73 [0.71, 0.76]), with more modest effects for hospitalization due to respiratory infections (0.83 [0.77, 0.90]), and all-cause hospitalizations (0.96 [0.95, 0.98]). The relative effects were somewhat greater in younger patients but with no material difference between men and women. In validation analyses, effects were not significant for consecutive years without vaccination (0.96 [0.92, 1.00]) or hospitalization due to cancer (1.02 [0.84, 1.22]).

Conclusion

In HF patients, influenza vaccination is associated with reduced risk of hospitalizations, especially for cardiovascular disease. Improved efforts for wider uptake of vaccination among HF patients are needed.

Prevalence and prognostic importance of precipitating factors leading to heart failure hospitalization: recurrent hospitalizations and mortality

AIMS

Hospitalizations for heart failure (HF) are common and are associated with significant morbidity, mortality and cost. However, precipitating factors leading to HF hospitalization and their importance with respect to subsequent outcomes are not well understood.

METHODS AND RESULTS

The symptoms and signs present at admission and investigator-identified factors thought to have contributed to the first adjudicated HF hospitalization in the Candesartan in Heart Failure: Assessment of Reduction in Mortality and Morbidity (CHARM) programme were prospectively collected and stratified by ejection fraction (EF). Potential precipitants were collected using a specifically designed case report form and categorized according to the presence of cardiovascular (CV), non-CV and unknown factors. Associations between these factors and subsequent rehospitalization and mortality rates were examined. Of 1668 patients who experienced HF hospitalization, 1152 had reduced EF (≤40%, HFrEF) and 516 had preserved EF (HFpEF). Overall, 54% had CV, 32% had non-CV and 14% had unknown factors thought to have precipitated HF, with similar proportions in the HFrEF and HFpEF groups. The most common precipitants were arrhythmia (15%), other non-CV factors (11%) and respiratory infection (10%). Subsequent CV readmission rates were highest in those whose initial HF hospitalization was precipitated by CV factors. However, mortality rates were similar among patients with any of the three categories of precipitating factors. Results were similar in HFrEF and HFpEF.

CONCLUSIONS

Among chronic HF patients hospitalized for decompensation, the investigator-reported precipitating factor was not associated with the subsequent mortality rate, but was associated with type of readmission: readmissions for CV reasons were more likely when the index precipitant was CV.