Influenza vaccination as a novel means of preventing coronary heart disease: Effectiveness in older adults

Effectiveness of influenza vaccines in preventing acute cardiovascular events within 1 year in Beijing, China

Controversies persist about the protective effects of vaccines against acute cardiovascular events. Using electronic medical records from hospitals and influenza vaccine administration data in Beijing, China, we studied individuals vaccinated between January 1, 2016, and December 31, 2018, who experienced at least one acute cardiovascular event within two years. A self-controlled case series design calculated the relative incidence (RI) and 95% confidence interval (CI) of acute cardiovascular events within one year after vaccination. Among 1647 participants (median age: 65 years, 38.43% female), the risk of events 29-365 days post-vaccination was 0.76 times the baseline level (RI: 0.76; 95% CI: 0.68-0.84). The protective effect was more pronounced in younger participants (P = 0.043) and those without cardiovascular history (P < 0.001), while acute respiratory infection (P = 0.986) and vaccination frequency (P = 0.272) had no impact. Influenza vaccines offer protection against acute cardiovascular events for at least one year, suggesting potential for cardiovascular disease prevention.

Podcast: Influenza-Associated Complications and the Impact of Vaccination on Public Health

Influenza is primarily considered an acute respiratory infection but can lead to a myriad of medium and long-term sequelae across every major organ system in the body. Increasing awareness, gaining broader understanding of its mechanistic pathways, identifying at-risk individuals, and determining how to better protect them could help minimize its impact. The aim of this podcast, featuring Dr Stefania Maggi, Dr Annemarijn de Boer, and Dr Melissa K. Andrew, is to outline the main influenza complications and their impact beyond acute respiratory disease, as well as highlighting vaccination as a tool at our disposal. Both physical and cognitive function can be affected as a result of influenza infection, notably in frailer individuals, which in turn may lead to a loss of independence. Observational studies have identified beneficial effects of vaccination for cardioprotection as well as preventing dementia, but more evidence is required. In conclusion, influenza can cause a wide array of complications, which vaccination may help prevent.Podcast available for this article.

Estimated health and economic impact of using high-dose influenza vaccine on respiratory and circulatory plus respiratory hospitalizations of older adults in Australia

Background

Standard dose influenza vaccine provides moderate protection from infection, but with lower effectiveness among the elderly. High dose and adjuvanted vaccines (HD-TIV and aTIV) were developed to address this. This study aims to estimate the incremental health and economic impact of using HD-TIV (high dose trivalent vaccine) instead of aTIV (adjuvanted trivalent vaccine) on respiratory and circulatory plus respiratory hospitalizations of older people (≥65 years) in Australia.

Methods

This is a modelling study comparing predicted hospitalization outcomes in people receiving HD-TIV or aTIV during an average influenza season in Australia. Hospitalization records of Australian adults ≥65 years of age from 01 April to 30 November during 15 influenza seasons (2002-2017 excluding 2009, which was a pandemic) were extracted from the Australian Institute of Health and Welfare [AIHW] and used to calculate hospitalisation rates during an average season. Relative vaccine effectiveness data for aTIV and HD-TIV were used to estimate morbidity burden related to influenza.

Results

Between 2002 and 2017, the average respiratory hospitalization rate among older people during influenza season (April-November) was 3,445/100,000 population-seasons, with an average cost of AU$ 7,175 per admission. The average circulatory plus respiratory hospitalization rate among older Australian people during that time was 10,393/100,000 population-seasons, with an average cost of AU$ 7829 per admission. For older Australians, HD-TIV may avert an additional 6,315-9,410 respiratory admissions each year, with an incremental healthcare cost saving of AU$ 15.9-38.2 million per year compared to aTIV. Similar results were also noted for circulatory plus respiratory hospitalizations.

Conclusions

From the modelled estimations, HD-TIV was associated with less economic burden and fewer respiratory, and circulatory plus respiratory hospitalizations than aTIV for older Australians.

Impact of influenza, herpes zoster, and pneumococcal vaccinations on the incidence of cardiovascular events in subjects aged over 65 years: a systematic review

This systematic review aims to summarize the impact of vaccination against influenza, shingles, and pneumococcus on the incidence on the risk of cardiovascular events in the elderly. This protocol was developed in accordance with PRISMA guidelines. We conducted a literature search and identified all relevant articles published regarding the matter up to September 2022. We retrieved 38 studies (influenza vaccine = 33, pneumococcal vaccine = 5, and zoster vaccine = 2). A total of 28 and 2 studies have shown that influenza and pneumococcal vaccines significantly lower the risk of cardiovascular disease in the elderly. Also, repeated influenza vaccination shows a consistent and dose-dependent protective effect against acute coronary syndromes and stroke. Moreover, dual influenza and pneumococcal vaccination was associated with lower risks of some cardiovascular events (stroke, congestive heart failure, ischemic heart disease, and myocardial infarction). However, the impact of PCV13 on cardiovascular events has not been studied, nor has the currently recommended vaccination schedule (PCV13 + PPV23). As for herpes zoster vaccination, only the protective effect against stroke has been studied with the live attenuated herpes zoster vaccine, but no studies have been conducted with the recombinant subunit herpes zoster vaccine. This review outlines the benefits of the vaccines mentioned above beyond their preventive action on infectious diseases. It is intended for health professionals who wish to inform and advise their elderly patients.

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.

Pleiotropic Effects of Influenza Vaccination

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

Maintaining a 'fit' immune system: the role of vaccines

INTRODUCTION

Conventionally, vaccines are thought to induce a specific immune response directed against a target pathogen. Long recognized but poorly understood nonspecific benefits of vaccination, such as reduced susceptibility to unrelated diseases or cancer, are now being investigated and may be due in part to "trained immunity'.

AREAS COVERED

We discuss 'trained immunity' and whether vaccine-induced 'trained immunity' could be leveraged to prevent morbidity due to a broader range of causes.

EXPERT OPINION

The prevention of infection i.e. maintaining homeostasis by preventing the primary infection and resulting secondary illnesses, is the pivotal strategy used to direct vaccine design and may have long-term, positive impacts on health at all ages. In the future, we anticipate that vaccine design will change to not only prevent the target infection (or related infections) but to generate positive modifications to the immune response that could prevent a wider range of infections and potentially reduce the impact of immunological changes associated with aging. Despite changing demographics, adult vaccination has not always been prioritized. However, the SARS-CoV-2 pandemic has demonstrated that adult vaccination can flourish given the right circumstances, demonstrating that harnessing the potential benefits of life-course vaccination is achievable for all.

Clinical impact of influenza vaccination after ST- and non-ST-segment elevation myocardial infarction - insights from the IAMI trial

BACKGROUND

Influenza vaccination early after myocardial infarction (MI) improves prognosis but vaccine effectiveness may differ dependent on type of MI.

METHODS

A total of 2,571 participants were prospectively enrolled in the Influenza vaccination after myocardial infarction (IAMI) trial and randomly assigned to receive in-hospital inactivated influenza vaccine or saline placebo. The trial was conducted at 30 centers in eight countries from October 1, 2016 to March 1, 2020. Here we report vaccine effectiveness in the 2,467 participants with ST-segment elevation MI (STEMI, n = 1,348) or non-ST-segment elevation MI (NSTEMI, n = 1,119). The primary endpoint was the composite of all-cause death, MI, or stent thrombosis at 12 months. Cumulative incidence of the primary and key secondary endpoints by randomized treatment and NSTEMI/STEMI was estimated using the Kaplan-Meier method. Treatment effects were evaluated with formal interaction testing to assess for effect modification.

RESULTS

Baseline risk was higher in participants with NSTEMI. In the NSTEMI group the primary endpoint occurred in 6.5% of participants assigned to influenza vaccine and 10.5% assigned to placebo (hazard ratio [HR], 0.60; 95% CI, 0.39-0.91), compared to 4.1% assigned to influenza vaccine and 4.5% assigned to placebo in the STEMI group (HR, 0.90; 95% CI, 0.54-1.50, P = .237 for interaction). Similar findings were seen for the key secondary endpoints of all-cause death and cardiovascular death. The Kaplan-Meier risk difference in all-cause death at one year was more pronounced in participants with NSTEMI (NSTEMI: HR, 0.47; 95% CI 0.28-0.80, STEMI: HR, 0.86; 95% CI, 0.43-1.70, interaction P = .028).

CONCLUSIONS

The beneficial effect of influenza vaccination on adverse cardiovascular events may be enhanced in patients with NSTEMI compared to those with STEMI.

The link between influenza and myocardial infarction: vaccination protects

The association between influenza and cardiovascular disease has been known since the influenza pandemics of the early years of the last century. This association is more consistent and more lasting in the case of particularly severe infections. Several pathogens, including influenza viruses, can modulate the inflammatory response and influence the biology of atherosclerotic plaque to rupture it and cause a Type 1 myocardial infarction. Clinically relevant viral infections can also exacerbate pre-existing cardiovascular disease and contribute to the development of a Type 2 myocardial infarction through an increase in the metabolic demands of the myocardial tissue for fever and tachycardia and the possible induction of hypoxaemia. Evidence of a relevant protective efficacy of influenza vaccination provides further robust and convincing support for a causal link between influenza and myocardial infarction. Consistent cardiovascular protection linked to influenza vaccination has also been demonstrated in patients with recent myocardial infarction to suggest the possibility that this procedure may become an integral part of in-hospital management of acute coronary syndromes. Despite the solidity of these evidences, acknowledged by the guidelines that recommend influenza vaccination in patients at increased cardiovascular risk, still today an unacceptably high proportion of patients at high cardiovascular risk do not receive flu vaccination. Despite some potential limitations of the current flu vaccination, its advantages in terms of reducing cardiovascular events and related mortality are still such as to justify its wide use, especially, but not limited to, in patients with high cardiovascular risk.

High-dose influenza vaccines for the prevention of hospitalization due to cardiovascular events in older adults in the nursing home: Post-hoc analysis of a cluster-randomized trial

Older adults are at high risk of major acute cardiovascular events (MACE) linked to influenza illness andpreventable by influenza vaccination. It is unknown whether high-dose vaccine might incrementally reduce the risk of MACE.We conducted a post-hoc analysis of data collected from a pragmatic cluster randomized study of 823 nursing homes (NH) randomized to standard-dose (SD) or high-dose (HD) influenza vaccine in the 2013-14 season. Adults age 65 year or older who are Medicare-enrolled long-stay residents were included in the analysis.There were no statistically significant differences in hospitalization for MACE, acute coronary syndromes (ACS), stroke or heart failure between the HD and SD arms. However, in the fee-for-service group, participants in the HD arm had significantly decreased risk of hospitalization for respiratory problems, which was not observed in the Medicare Advantage group.High-dose influenza vaccine was not shown to be incrementally protective against MACE relative to standard-dose vaccine.

Influenza Vaccination Assessment according to a Value-Based Health Care Approach

Background: Seasonal influenza has a considerable public health impact, and vaccination is the key to preventing its consequences. Our aim was to describe how the value of influenza vaccination is addressed in the scientific literature considering a new value framework based on four pillars (personal, allocative, technical, and societal value). Methods: A systematic review was conducted by querying three databases. The analysis was performed on international studies focused on influenza vaccination value, and the four value pillars were taken into consideration for their description. Results: Overall, 40 studies were considered. Most of them focused on influenza vaccination in the general population (27.5%), emphasizing its value for all age groups. Most studies addressed technical value (70.4%), especially in terms of economic models and cost drivers to be considered for the economic evaluations of influenza vaccines, and societal value (63%), whereas few dealt with personal (37%) and allocative values (22.2%). Conclusions: The whole value of influenza vaccination is still not completely recognized. Knowledge and communication of the whole value of influenza vaccination is essential to guide value-based health policies. To achieve this goal, it is necessary to implement initiatives that involve all relevant stakeholders.

Looking back on 50 years of literature to understand the potential impact of influenza on extrapulmonary medical outcomes

We conducted a scoping review of the epidemiological literature from the past 50 years to document the contribution of influenza virus infection to extrapulmonary clinical outcomes. We identified 99 publications reporting 243 associations using many study designs, exposure and outcome definitions, and methods. Laboratory confirmation of influenza was used in only 28 (12%) estimates, mostly in case-control and self-controlled case series study designs. We identified 50 individual clinical conditions associated with influenza. The most numerous estimates were of cardiocirculatory diseases, neurological/neuromuscular diseases, and fetal/newborn disorders, with myocardial infarction the most common individual outcome. Due to heterogeneity, we could not generate summary estimates of effect size, but of 130 relative effect estimates, 105 (81%) indicated an elevated risk of extrapulmonary outcome with influenza exposure. The literature is indicative of systemic complications of influenza virus infection, the requirement for more effective influenza control, and a need for robust confirmatory studies.

Cost-benefit analysis of vaccination against four preventable diseases in older adults: Impact of an aging population

OBJECTIVE

This exploratory study estimates the economic value of the current vaccination program and increased coverage against four preventable diseases in older adults in the United States (US).

METHODS

A population-based, age-structured economic model was used to conduct a cost-benefit analysis of vaccination against influenza, pertussis, herpes zoster, and pneumococcal disease among US adults aged 50 years and older, accounting for aging of the population. The model used separate decision trees for each disease to project the discounted number of vaccinated individuals, number of disease cases, and direct medical and indirect costs (2018 US$) over a 30-year period. Benefit-cost ratios (BCRs) and net present values were calculated for two primary analyses comparing current vaccination coverage versus no vaccination and comparing increased coverage versus current coverage. Key parameter values were varied in deterministic sensitivity analyses.

RESULTS

Current adult vaccination coverage (vs. no vaccination) is estimated to result in nearly 65 million averted disease cases, $185 billion averted costs of cases, and $136 billion in incremental vaccination costs over a 30-year period from a societal perspective (BCR = 1.4). Increased vaccination coverage (vs. current coverage) is associated with over 33 million additional averted disease cases, $96 billion additional averted costs of cases, and nearly $83 billion in incremental vaccination costs, resulting in a societal BCR of 1.2 over 30 years. Deterministic sensitivity analyses demonstrated that results were most sensitive to disease incidence, vaccine efficacy, and productivity costs for time required for vaccination.

CONCLUSIONS

Study results highlight the economic value of vaccination programs for older adults in the US and indicate that efforts to further increase vaccination coverage may be warranted and economically justifiable.

[Vaccination against community acquired pneumonia in adults. Update 2021 of the position paper by Neumoexpertos en Prevención Group]

Community-acquired pneumonia (CAP) continues to be an important cause of morbidity and mortality in adults. The aim of this study is to update the practical prevention guide for CAP through vaccination in Spain developed in 2016 and updated in 2018, based on available vaccines and evidence through bibliographic review and expert opinion. The arrival of COVID-19 as a new cause of CAP and the recent availability of safe and effective vaccines constitutes the most significant change. Vaccines against pneumococcus, influenza, pertussis and COVID-19 can help to reduce the burden of disease from CAP and its associated complications. The available evidence supports the priority indications established in this guide, and it would be advisable to try to achieve a widespread dissemination and implementation of these recommendations in routine clinical practice.

Proatherogenic Sialidases and Desialylated Lipoproteins: 35 Years of Research and Current State from Bench to Bedside

This review summarizes the main achievements in basic and clinical research of atherosclerosis. Focusing on desialylation as the first and the most important reaction of proatherogenic pathological cascade, we speak of how desialylation increases the atherogenic properties of low density lipoproteins and decreases the anti-atherogenic properties of high density lipoproteins. The separate sections of this paper are devoted to immunogenicity of lipoproteins, the enzymes contributing to their desialylation and animal models of atherosclerosis. In addition, we evaluate the available experimental and diagnostic protocols that can be used to develop new therapeutic approaches for atherosclerosis.

Influenza Vaccination in Patients With Congenital Heart Disease in the Pre-COVID-19 Era: Coverage Rate, Patient Characteristics, and Outcomes

BACKGROUND

Influenza vaccination is the most commonly recommended immune prevention strategy. However, data on influenza vaccination in patients with congenital heart disease (CHD) are scarce. In this study, our goals were to: (1) measure vaccination coverage rates (VCRs) for influenza in a large cohort of children, adolescents, and adults with CHD; (2) identity patient characteristics as predictors for vaccination; and (3) investigate the effect of influenza vaccination on hospitalization.

METHODS

A nationwide cohort study in Belgium included 16,778 patients, representing 134,782 vaccination years, from the Belgian Congenital Heart Disease Database Combining Administrative and Clinical Data (BELCODAC). Data over 9 vaccination years (2006-2015) were used, and patients were stratified into 5 age cohorts: 6 months to 4 years; 5-17 years; 18-49 years; 50-64 years; and 65 years and older.

RESULTS

In the respective age cohorts, the VCR was estimated to be 6.6%, 8.0%, 23.9%, 46.6%, and 72.8%. There was a steep increase in VCRs as of the age of 40 years. Multivariable logistic regression showed that higher anatomical complexity of CHD, older age, presence of genetic syndromes, and previous cardiac interventions were associated with significantly higher VCRs. Among adults, men had lower and pregnant women had higher VCRs. The association between influenza vaccination and all-cause hospitalization was not significant in this study.

CONCLUSIONS

The influenza VCR in people with CHD is low, especially in children and adolescents. Older patients, particularly those with complex CHD, are well covered. Our findings should inform vaccination promotion strategies in populations with CHD.

Relationship Between Influenza, Temperature, and Type 1 Myocardial Infarction: An Ecological Time-Series Study

Background Previous studies investigating the relationship of influenza with acute myocardial infarction (AMI) have not distinguished between AMI types 1 and 2. Influenza and cold temperature can explain the increased incidence of AMI during winter but, because they are closely related in temperate regions, their relative contribution is unknown. Methods and Results The temporal relationship between incidence rates of AMI with demonstrated culprit plaque (type 1 AMI) from the regional primary angioplasty network and influenza, adjusted for ambient temperature, was studied in Madrid region (Spain) during 5 influenza seasons (from June 2013 to June 2018). A time-series analysis with quasi-Poisson regression models and distributed lag-nonlinear models was used. The incidence rate of type 1 AMI according to influenza vaccination status was also explored. A total of 8240 cases of confirmed type 1 AMI were recorded. The overall risk ratio (RR) of type 1 AMI during epidemic periods, adjusted for year, month, and temperature, was 1.23 (95% CI, 1.03-1.47). An increase of weekly influenza rate of 50 cases per 100 000 inhabitants resulted in an RR for type 1 AMI of 1.16 (95% CI, 1.09-1.23) during the same week, disappearing 1 week after. When adjusted for influenza, a decrease of 1ºC in the minimum temperature resulted in an increase of 2.5% type 1 AMI. Influenza vaccination was associated with a decreased risk of type 1 AMI in subjects aged 60 to 64 years (RR, 0.58; 95% CI, 0.47-0.71) and ≥65 years (RR, 0.53; 95% CI, 0.49-0.57). Conclusions Influenza and cold temperature were both independently associated with an increased risk of type 1 AMI, whereas vaccination was associated with a reduced risk among older patients.

Excess mortality at Christmas due to cardiovascular disease in the HUNT study prospective population-based cohort in Norway

Background

Although it is known that winter inclusive of the Christmas holiday period is associated with an increased risk of dying compared to other times of the year, very few studies have specifically examined this phenomenon within a population cohort subject to baseline profiling and prospective follow-up. In such a cohort, we sought to determine the specific characteristics of mortality occuring during the Christmas holidays.

Methods

Baseline profiling and outcome data were derived from a prospective population-based cohort with longitudinal follow-up in Central Norway - the Trøndelag Health (HUNT) Study. From 1984 to 1986, 88% of the target population comprising 39,273 men and 40,353 women aged 48 ± 18 and 50 ± 18 years, respectively, were profiled. We examined the long-term pattern of mortality to determine the number of excess (all-cause and cause-specific) deaths that occurred during winter overall and, more specifically, the Christmas holidays.

Results

During 33.5 (IQR 17.1–34.4) years follow-up, 19,879 (50.7%) men and 19,316 (49.3%) women died at age-adjusted rate of 5.3 and 4.6 deaths per 1000/annum, respectively. Overall, 1540 (95% CI 43–45 deaths/season) more all-cause deaths occurred in winter (December to February) versus summer (June to August), with 735 (95% CI 20–22 deaths per season) of these cardiovascular-related. December 25th–27th was the deadliest 3-day period of the year; being associated with 138 (95% CI 96–147) and 102 (95% CI 72–132) excess all-cause and cardiovascular-related deaths, respectively. Accordingly, compared to 1st–21st December (equivalent winter conditions), the incidence rate ratio of all-cause mortality increased to 1.22 (95% CI 1.16–1.27) and 1.17 (95% 1.11–1.22) in men and women, respectively, during the next 21 days (Christmas/New Year holidays). All observed differences were highly significant (P < 0.001). A less pronounced pattern of mortality due to respiratory illnesses (but not cancer) was also observed.

Conclusion

Beyond a broader pattern of seasonally-linked mortality characterised by excess winter deaths, the deadliest time of year in Central Norway coincides with the Christmas holidays. During this time, the pattern and frequency of cardiovascular-related mortality changes markedly; contrasting with a more stable pattern of cancer-related mortality. Pending confirmation in other populations and climates, further research to determine if these excess deaths are preventable is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10503-7.

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.