CLINICAL PRACTICE. Influenza Vaccination

Designing a multi-epitope influenza vaccine: an immunoinformatics approach

Influenza continues to be one of the top public health problems since it creates annual epidemics and can start a worldwide pandemic. The virus's rapid evolution allows the virus to evade the host defense, and then seasonal vaccines need to be reformulated nearly annually. However, it takes almost half a year for the influenza vaccine to become accessible. This delay is especially concerning in the event of a pandemic breakout. By producing the vaccine through reverse vaccinology and phage display vaccines, this time can be reduced. In this study, epitopes of B lymphocytes, cytotoxic T lymphocytes, and helper T lymphocytes of HA, NA, NP, and M2 proteins from two strains of Influenza A were anticipated. We found two proper epitopes (ASFIYNGRL and LHLILWITDRLFFKC) in Influenza virus proteins for CTL and HTL cells, respectively. Optimal epitopes and linkers in silico were cloned into the N-terminal end of M13 protein III (pIII) to create a multi-epitope-pIII construct, i.e., phage display vaccine. Also, prediction of tertiary structure, molecular docking, molecular dynamics simulation, and immune simulation were performed and showed that the designed multi-epitope vaccine can bind to the receptors and stimulate the immune system response.

One-pot synthesis, characterization and antiviral properties of new benzenesulfonamide-based spirothiazolidinones

A novel series of benzenesulfonamide substituted spirothiazolidinone derivatives (3a-j) were synthesized, characterized and evaluated for their antiviral activity. The spirocyclic compounds were prepared by the condensation of 4-(aminosulfonyl)-2-methoxybenzohydrazide, appropriate cyclic ketones and 2-mercaptopropionic acid in a one-pot reaction. The structures of the new compounds were established by IR, 1H NMR, 13C NMR (APT), and elemental analysis. The new compounds were evaluated in vitro antiviral activity against influenza A/H1N1, A/H3N2 and B viruses, as well as herpes simplex virus type 1 (HSV-1), respiratory syncytial virus (RSV) and yellow fever virus (YFV). Two derivatives bearing propyl (3d) and tert-butyl (3e) substituents at position 8 of the spiro ring exhibited activity against influenza A/H1N1 virus with EC50 values in the range of 35-45 µM and no cytotoxicity at 100 μM, the highest concentration tested.

Impact of health education on promoting influenza vaccination health literacy in primary school students: a cluster randomised controlled trial protocol

INTRODUCTION

Influenza is a major public health threat, and vaccination is the most effective prevention method. However, vaccination coverage remains suboptimal. Low health literacy regarding influenza vaccination may contribute to vaccine hesitancy. This study aims to evaluate the effect of health education interventions on influenza vaccination rates and health literacy.

METHODS AND ANALYSIS

This cluster randomised controlled trial will enrol 3036 students in grades 4-5 from 20 primary schools in Dongguan City, China. Schools will be randomised to an intervention group receiving influenza vaccination health education or a control group receiving routine health education. The primary outcome is the influenza vaccination rate. Secondary outcomes include health literacy levels, influenza diagnosis rate, influenza-like illness incidence and vaccine protection rate. Data will be collected through questionnaires, influenza surveillance and self-reports at baseline and study conclusion.

ETHICS AND DISSEMINATION

Ethical approval has been sought from the Ethics Committee of the School of Public Health, Sun Yat-sen University. Findings from the study will be made accessible to both peer-reviewed journals and key stakeholders.

TRIAL REGISTRATION NUMBER

NCT06048406.

Assessing the impact of climatic variability on acute respiratory diseases across diverse climatic zones in South Africa

Acute respiratory diseases are a significant public health concern in South Africa, with climatic variables such as temperature and rainfall being key influencers. This study investigates the associations between these variables and the prevalence of acute respiratory diseases in Johannesburg, Cape Town, and Gqeberha (Port Elizabeth), representing distinct climatic zones. Spearman's correlation analyses showed negative correlations in Johannesburg for respiratory disease claims with maximum temperature (r = -0.12, p < 0.0001) and mean temperature (r = -0.13, p < 0.0001), and a negative correlation with daily rainfall (r = -0.12, p < 0.0001). Cape Town demonstrated a negative correlation with maximum temperature (r = -0.18, p < 0.0001) and a positive correlation with rainfall (r = 0.08, p < 0.0001). Utilizing Distributed Lag Non-linear Models (DLNM), the study revealed that in Johannesburg, the relative risk (RR) of respiratory claims increases notably at temperatures below 12 °C, and again at a Tmax between 16 and 23 °C. The risk escalates further at >30 °C, although with a considerable error margin. For Cape Town, a stable level of moderate RR is seen from Tmax 15-24 °C, with a significant increase in RR and error margin above 30 °C. In Gqeberha, the DLNM results are less definitive, reflecting the city's moderate climate and year-round rainfall. The RR of acute respiratory diseases did not show clear patterns with temperature changes, with increasing error margins outside the 22 °C threshold. These findings emphasize the imperative for region-specific public health strategies that account for the complex, non-linear influences of climate on respiratory health. This detailed understanding of the climate-health nexus provides a robust basis for enhancing public health interventions and future research directed at reducing the impacts of climate factors.

Reduced mortality, complications, and economic burden among medicare beneficiaries receiving influenza antivirals

INTRODUCTION

Antiviral therapy may be underutilized in patients at high risk for increased clinical and economic burden (e.g. older adults). We aimed to examine the benefits associated with antiviral treatment of seasonal influenza among treated and untreated Medicare beneficiaries.

METHODS

This retrospective study of Medicare Claims Research Identifiable Files identified patients ≥66 years old with an influenza diagnosis in outpatient setting between October 2016-March 2019 (flu seasons 2016-2018). Index date defined as date of first claim with influenza diagnosis; baseline as the 12 months pre-index. Treated patients received antivirals ≤2 days from index. Untreated patients had no antivirals ≤6 months post-index. Treated/untreated patients were 1:1 propensity score matched. Outcomes (death, all-cause and respiratory-related healthcare resource utilization [HCRU] and costs) were assessed until death or up to 6 months post-index. Descriptive statistics were reported; Kaplan-Meier estimation was used for survival over time.

RESULTS

Among 116,901 matched patient pairs, all-cause mortality within 6 months from index diagnosis was 1.6% among treated versus 4.3% among untreated patients. Rates (treated versus untreated) of all-cause inpatient hospitalizations during follow-up were 13.9% versus 22.7% and respiratory-related hospitalizations were 4.2% versus 9.0%. Mean (SD) total all-cause and respiratory-related costs were $9,830 ($18,616.0) and $900 ($4016.4) among the treated, respectively, versus $13,207 ($24,405.1) and $2,024 ($7,623.7) among untreated, respectively. All differences were statistically significant (p < 0.001).

CONCLUSIONS

Lack of antiviral treatment is associated with increased mortality, HCRU, and economic burden in older Medicare beneficiaries with seasonal influenza. Future research should investigate whether the choice of antivirals affects influenza burden.

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.

Development and applications of mRNA treatment based on lipid nanoparticles

Nucleic acid-based therapies such as messenger RNA have the potential to revolutionize modern medicine and enhance the performance of existing pharmaceuticals. The key challenges of mRNA-based therapies are delivering the mRNA safely and effectively to the target tissues and cells and controlling its release from the delivery vehicle. Lipid nanoparticles (LNPs) have been widely studied as drug carriers and are considered to be state-of-the-art technology for nucleic acid delivery. In this review, we begin by presenting the advantages and mechanisms of action of mRNA therapeutics. Then we discuss the design of LNP platforms based on ionizable lipids and the applications of mRNA-LNP vaccines for prevention of infectious diseases and for treatment of cancer and various genetic diseases. Finally, we describe the challenges and future prospects of mRNA-LNP therapeutics.

A Review of the Pharmacokinetic Characteristics of Immune Checkpoint Inhibitors and Their Clinical Impact Factors

Immune checkpoint inhibitors (ICIs) have been shown to be significant in improving the overall survival rate in certain malignancies with poor prognoses. However, only 20-40% of patients achieve long-term benefits, highlighting the relevance of the factors that influence the treatment, which can help clinicians improve their results and guide the development of new immune checkpoint therapies. In this study, the current pharmacokinetic aspects associated with the ICIs and the factors influencing clinical efficacy were characterised, including in terms of drug metabolism, drug clearance, hormonal effects and immunosuppressive effects.

Expression of Influenza M2e-NP Recombinant Fusion Protein in Escherichia coli BL21 (DE3) and Its Binding to Antibodies

The current influenza vaccines only confer protection against the circulating influenza subtypes, therefore universal vaccines are needed to prevent upcoming influenza outbreaks caused by emerging influenza subtypes. The extracellular domain of influenza A M2 protein (M2e) is highly conserved among different subtypes of influenza A viruses, and it is able to elicit protective immunity against the viruses. The influenza nucleoprotein (NP) was used to display the M2e in this study due to its promising T-cell response and adjuvanticity. The M2e gene was fused to the 5'-end of the NP gene and then cloned into pRSET B vector. The DNA sequencing analysis revealed six point mutations in the M2e-NP fusion gene, including one mutation in the M2e peptide and five mutations in the NP. The mutations were reverted using PCR site-directed mutagenesis. The recombinant plasmids (pRSET B-M2e-NP and pRSET B-mM2e-NP) were introduced into Escherichia coli (E. coli) BL21 (DE3) for protein expression. The mutated and non-mutated proteins were subsequently expressed and named mM2e-NP and M2e-NP, respectively. The expression of mM2e-NP and M2e-NP was not affected by the mutations. The binding of anti-M2e antibody to the purified native mM2e-NP and M2e-NP also remained active. However, when the anti-NP antibody was tested, the signal produced by mM2e-NP was very weak. The results implied that the amino acid changes in the NP had adversely impacted on the conformation of mM2e-NP and subsequently affected the antibody binding. In light of the remarkable antibody binding to the M2e-NP fusion protein, this study highly recommends the potential of M2e-NP as a universal influenza vaccine candidate.

CD4 T cell epitope abundance in ferritin core potentiates responses to hemagglutinin nanoparticle vaccines

Nanoparticle vaccines based on H. pylori ferritin are increasingly used as a vaccine platform for many pathogens, including RSV, influenza, and SARS-CoV-2. They have been found to elicit enhanced, long-lived B cell responses. The basis for improved efficacy of ferritin nanoparticle vaccines remains unresolved, including whether recruitment of CD4 T cells specific for the ferritin component of these vaccines contributes to cognate help in the B cell response. Using influenza HA-ferritin nanoparticles as a prototype, we have performed an unbiased assessment of the CD4 T cell epitope composition of the ferritin particles relative to that contributed by influenza HA using mouse models that express distinct constellations of MHC class II molecules. The role that these CD4 T cells play in the B cell responses was assessed by quantifying follicular helper cells (TFH), germinal center (GC) B cells, and antibody secreting cells. When mice were immunized with equimolar quantities of soluble HA-trimers and HA-Fe nanoparticles, HA-nanoparticle immunized mice had an increased overall abundance of TFH that were found to be largely ferritin-specific. HA-nanoparticle immunized mice had an increased abundance of HA-specific isotype-switched GC B cells and HA-specific antibody secreting cells (ASCs) relative to mice immunized with soluble HA-trimers. Further, there was a strong, positive correlation between CD4 TFH abundance and GC B cell abundance. Thus, availability of helper CD4 T cell epitopes may be a key additional mechanism that underlies the enhanced immunogenicity of ferritin-based HA-Fe-nanoparticle vaccines.

Programmed Cell Death Protein 1 Axis Inhibition in Viral Infections: Clinical Data and Therapeutic Opportunities

A vital function of the immune system is the modulation of an evolving immune response. It is responsible for guarding against a wide variety of pathogens as well as the establishment of memory responses to some future hostile encounters. Simultaneously, it maintains self-tolerance and minimizes collateral tissue damage at sites of inflammation. In recent years, the regulation of T-cell responses to foreign or self-protein antigens and maintenance of balance between T-cell subsets have been linked to a distinct class of cell surface and extracellular components, the immune checkpoint molecules. The fact that both cancer and viral infections exploit similar, if not the same, immune checkpoint molecules to escape the host immune response highlights the need to study the impact of immune checkpoint blockade on viral infections. More importantly, the process through which immune checkpoint blockade completely changed the way we approach cancer could be the key to decipher the potential role of immunotherapy in the therapeutic algorithm of viral infections. This review focuses on the effect of programmed cell death protein 1/programmed death-ligand 1 blockade on the outcome of viral infections in cancer patients as well as the potential benefit from the incorporation of immune checkpoint inhibitors (ICIs) in treatment of viral infections.

Acute Lymphocyte Myocarditis Associated with Influenza Vaccination

An elderly patient was admitted to our hospital for acute heart failure soon after receiving influenza vaccination. On admission, chest radiography revealed pulmonary edema. An electrocardiogram showed poor R progression, and echocardiography showed diffuse hypokinesis and myocardial edema. The serum troponin level was elevated. A histopathological evaluation indicated active myocarditis with lymphocyte-predominant infiltrates. A drug-induced lymphocyte stimulation test (DLST) was positive. The patient rapidly recovered from heart failure after treatment with conventional heart failure drugs, such as intravenous diuretics and vasodilators. These experimental data and the clinical course suggest that influenza vaccination was responsible for heart failure due to acute lymphocyte myocarditis.

Influenza Vaccination in Cancer Patients Treated With Immune Checkpoint Inhibitors: A Systematic Review and Meta-analysis

The safety and efficacy of influenza vaccination is not well-studied in cancer patients receiving immune checkpoint inhibitors (ICIs). A systematic review and meta-analysis was performed aiming to summarize available data regarding influenza vaccination in ICI-treated cancer patients. Peer-reviewed studies or nonpeer-reviewed conference abstracts including ICI-treated cancer patients who received at least 1 dose of influenza vaccine were deemed eligible. A systematic search in PubMed/EMBASE was performed until October 26, 2021. Endpoints of interest included mortality as the primary outcome and secondary safety outcomes such as the incidence of immune-related adverse events (irAEs). Twenty-five studies were included in the systematic review, among which 9 were included in the meta-analysis. Meta-analysis of 3 studies (n=589, weighted age 64 y, men 61%, influenza vaccinated 32%) showed pooled odds ratio for death in influenza vaccinated versus nonvaccinated patients at 1.25 [(95% confidence intervals (CI): 0.81-1.92), P=non significant (NS)]. Meta-analysis of 6 studies studies (n=1285, weighted age 60 y, men 59%, influenza vaccinated 48%) showed pooled odds ratio for any irAEs in influenza vaccinated versus nonvaccinated patients at 0.82 [95% CI: 0.63-1.08, P=NS]. Similar results were observed in sensitivity analyses for serious irAEs, as well as when only peer-reviewed studies were included. Influenza vaccination appears to be a safe and reasonable intervention for cancer patients receiving ICIs. Most data are derived from retrospective observational studies. Randomized studies are needed to provide high-quality evidence.

Design, Synthesis, Molecular Docking Analysis and Biological Evaluations of 4-[(Quinolin-4-yl)amino]benzamide Derivatives as Novel Anti-Influenza Virus Agents

In this study, a series of 4-[(quinolin-4-yl)amino]benzamide derivatives as the novel anti-influenza agents were designed and synthesized. Cytotoxicity assay, cytopathic effect assay and plaque inhibition assay were performed to evaluate the anti-influenza virus A/WSN/33 (H1N1) activity of the target compounds. The target compound G07 demonstrated significant anti-influenza virus A/WSN/33 (H1N1) activity both in cytopathic effect assay (EC₅₀ = 11.38 ± 1.89 µM) and plaque inhibition assay (IC₅₀ = 0.23 ± 0.15 µM). G07 also exhibited significant anti-influenza virus activities against other three different influenza virus strains A/PR/8 (H1N1), A/HK/68 (H3N2) and influenza B virus. According to the result of ribonucleoprotein reconstitution assay, G07 could interact well with ribonucleoprotein with an inhibition rate of 80.65% at 100 µM. Furthermore, G07 exhibited significant activity target PA−PB1 subunit of RNA polymerase according to the PA−PB1 inhibitory activity prediction by the best pharmacophore Hypo1. In addition, G07 was well drug-likeness based on the results of Lipinski’s rule and ADMET prediction. All the results proved that 4-[(quinolin-4-yl)amino]benzamide derivatives could generate potential candidates in discovery of anti-influenza virus agents.

BNT162b2 Protection against the Omicron Variant in Children and Adolescents

BACKGROUND

Spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 (omicron) variant, which led to increased U.S. hospitalizations for coronavirus disease 2019 (Covid-19), generated concern about immune evasion and the duration of protection from vaccines in children and adolescents.

METHODS

Using a case-control, test-negative design, we assessed vaccine effectiveness against laboratory-confirmed Covid-19 leading to hospitalization and against critical Covid-19 (i.e., leading to receipt of life support or to death). From July 1, 2021, to February 17, 2022, we enrolled case patients with Covid-19 and controls without Covid-19 at 31 hospitals in 23 states. We estimated vaccine effectiveness by comparing the odds of antecedent full vaccination (two doses of BNT162b2 messenger RNA vaccine) at least 14 days before illness among case patients and controls, according to time since vaccination for patients 12 to 18 years of age and in periods coinciding with circulation of B.1.617.2 (delta) (July 1, 2021, to December 18, 2021) and omicron (December 19, 2021, to February 17, 2022) among patients 5 to 11 and 12 to 18 years of age.

RESULTS

We enrolled 1185 case patients (1043 [88%] of whom were unvaccinated, 291 [25%] of whom received life support, and 14 of whom died) and 1627 controls. During the delta-predominant period, vaccine effectiveness against hospitalization for Covid-19 among adolescents 12 to 18 years of age was 93% (95% confidence interval [CI], 89 to 95) 2 to 22 weeks after vaccination and was 92% (95% CI, 80 to 97) at 23 to 44 weeks. Among adolescents 12 to 18 years of age (median interval since vaccination, 162 days) during the omicron-predominant period, vaccine effectiveness was 40% (95% CI, 9 to 60) against hospitalization for Covid-19, 79% (95% CI, 51 to 91) against critical Covid-19, and 20% (95% CI, -25 to 49) against noncritical Covid-19. During the omicron period, vaccine effectiveness against hospitalization among children 5 to 11 years of age was 68% (95% CI, 42 to 82; median interval since vaccination, 34 days).

CONCLUSIONS

BNT162b2 vaccination reduced the risk of omicron-associated hospitalization by two thirds among children 5 to 11 years of age. Although two doses provided lower protection against omicron-associated hospitalization than against delta-associated hospitalization among adolescents 12 to 18 years of age, vaccination prevented critical illness caused by either variant. (Funded by the Centers for Disease Control and Prevention.).

Association of Online Search Trends With Vaccination in the United States: June 2020 Through May 2021

Stagnating COVID-19 vaccination rates and vaccine hesitancy remain a threat to public health. Improved strategies for real-time tracking and estimation of population-level behavior regarding vaccinations are needed. The aim of this study was to evaluate whether online search trends for COIVD-19 and influenza mirror vaccination rates. State-level weekly fraction of online searches for top vaccination-related search terms and CDC vaccination data were obtained from June 1, 2020, to May 31, 2021. Next, trends in online search and vaccination data for COVID-19 and influenza were analyzed for visual and quantitative correlation patterns using Spearman’s rank correlation analysis. Online searches in the US for COVID-19 vaccinations increased 2.71-fold (95% CI: 1.98-3.45) in the 4 weeks after the FDA emergency authorization compared to the precedent 4 weeks. In March-April 2021, US online searches reached a plateau that was followed by a decline of 83.3% (95% CI: 31.2%-135.3%) until May 31, 2021. The timing of peaks in online searches varied across US states. Online searches were strongly correlated with vaccination rates (r=0.71, 95% CI: 0.45 - 0.87), preceding actual reported vaccination rates in 44 of 51 states. Online search trends preceded vaccination trends by a median of 3.0 weeks (95% CI: 2.0-4.0 weeks) across all states. For influenza vaccination searches, seasonal peaks in September-October between 2016-2020 were noted. Influenza search trends highly correlated with the timing of actual vaccinations for the 2019-2020 (r=0.82, 95% CI: 0.64 – 0.93) and 2020-2021 season (r=0.91, 95% CI: 0.78 – 0.97). Search trends and real-world vaccination rates are highly correlated. Temporal alignment and correlation levels were higher for influenza vaccinations; however, only online searches for COVID-19 vaccination preceded vaccination trends. These findings indicate that US online search data can potentially guide public health efforts, including policy changes and identifying geographical areas to expand vaccination campaigns.

ARHGAP1 Transported with Influenza Viral Genome Ensures Integrity of Viral Particle Surface through Efficient Budozone Formation

Influenza viral particles are assembled at the plasma membrane concomitantly with Rab11a-mediated endocytic transport of viral ribonucleoprotein complexes (vRNPs). The mechanism of spatiotemporal regulation of viral budozone formation and its regulatory molecules on the endocytic vesicles remain unclear. Here, we performed a proximity-based proteomics approach for Rab11a and found that ARHGAP1, a Rho GTPase-activating protein, is transported through the Rab11a-mediated apical transport of vRNP. ARHGAP1 stabilized actin filaments in infected cells for the lateral clustering of hemagglutinin (HA) molecules, a viral surface membrane protein, to the budozone. Disruption of the HA clustering results in the production of virions with low HA content, and such virions were less resistant to protease and had enhanced antigenicity, presumably because reduced clustering of viral membrane proteins exposes hidden surfaces. Collectively, these results demonstrate that Rab11a-mediated endocytic transport of ARHGAP1 with vRNPs stimulates budozone formation to ensure the integrity of virion surface required for viral survival.

Effectiveness of BNT162b2 Vaccine against Critical Covid-19 in Adolescents

BACKGROUND

The increasing incidence of pediatric hospitalizations associated with coronavirus disease 2019 (Covid-19) caused by the B.1.617.2 (delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United States has offered an opportunity to assess the real-world effectiveness of the BNT162b2 messenger RNA vaccine in adolescents between 12 and 18 years of age.

METHODS

We used a case-control, test-negative design to assess vaccine effectiveness against Covid-19 resulting in hospitalization, admission to an intensive care unit (ICU), the use of life-supporting interventions (mechanical ventilation, vasopressors, and extracorporeal membrane oxygenation), or death. Between July 1 and October 25, 2021, we screened admission logs for eligible case patients with laboratory-confirmed Covid-19 at 31 hospitals in 23 states. We estimated vaccine effectiveness by comparing the odds of antecedent full vaccination (two doses of BNT162b2) in case patients as compared with two hospital-based control groups: patients who had Covid-19-like symptoms but negative results on testing for SARS-CoV-2 (test-negative) and patients who did not have Covid-19-like symptoms (syndrome-negative).

RESULTS

A total of 445 case patients and 777 controls were enrolled. Overall, 17 case patients (4%) and 282 controls (36%) had been fully vaccinated. Of the case patients, 180 (40%) were admitted to the ICU, and 127 (29%) required life support; only 2 patients in the ICU had been fully vaccinated. The overall effectiveness of the BNT162b2 vaccine against hospitalization for Covid-19 was 94% (95% confidence interval [CI], 90 to 96); the effectiveness was 95% (95% CI, 91 to 97) among test-negative controls and 94% (95% CI, 89 to 96) among syndrome-negative controls. The effectiveness was 98% against ICU admission and 98% against Covid-19 resulting in the receipt of life support. All 7 deaths occurred in patients who were unvaccinated.

CONCLUSIONS

Among hospitalized adolescent patients, two doses of the BNT162b2 vaccine were highly effective against Covid-19-related hospitalization and ICU admission or the receipt of life support. (Funded by the Centers for Disease Control and Prevention.).

Systematic review of the efficacy, effectiveness and safety of MF59® adjuvanted seasonal influenza vaccines for the prevention of laboratory-confirmed influenza in individuals ≥18 years of age

The most effective means of preventing seasonal influenza is through vaccination. In this systematic review, we investigated the efficacy, effectiveness and safety of MF59^® adjuvanted trivalent and quadrivalent influenza vaccines to prevent laboratory-confirmed influenza. A systematic literature search was conducted in electronic databases and grey literature sources up to 7 February 2020. Randomised controlled trials and non-randomised studies of interventions (NRSIs) were eligible for inclusion. The search returned 28,846 records, of which 48 studies on MF59^® adjuvanted vaccines met our inclusion criteria. No efficacy trials were identified. In terms of vaccine effectiveness (VE), MF59^® adjuvanted trivalent influenza vaccines were effective in preventing laboratory-confirmed influenza in older adults (aged ≥65 years) compared with no vaccination (VE = 45%, 95% confidence interval (CI) 23%-61%, 5 NRSIs across 3 influenza seasons). By subtype, significant effect was found for influenza A(H1N1) (VE = 61%, 95% CI 44%-73%) and B (VE = 29%, 95% CI 5%-46%), but not for A(H3N2). In terms of relative VE, there was no significant difference comparing MF59^® adjuvanted trivalent vaccines with either non-adjuvanted trivalent or quadrivalent vaccines. Compared with traditional trivalent influenza vaccines, MF59^® adjuvanted trivalent influenza vaccines were associated with a greater number of local adverse events (RR = 1.90, 95% CI 1.50-2.39) and systemic reactions (RR = 1.18, 95% CI 1.02-1.38). In conclusion, MF59^® adjuvanted trivalent influenza vaccines were found to be more effective than 'no vaccination'. Based on limited data, there was no significant difference comparing the effectiveness of MF59^® adjuvanted vaccines with their non-adjuvanted counterparts.

Systematic review of the efficacy, effectiveness and safety of recombinant haemagglutinin seasonal influenza vaccines for the prevention of laboratory-confirmed influenza in individuals ≥18 years of age

The most effective means of preventing seasonal influenza is through vaccination. In this systematic review, we investigated the efficacy, effectiveness and safety of recombinant haemagglutinin (HA) seasonal influenza vaccines to prevent laboratory-confirmed influenza. A systematic literature search was conducted in electronic databases and grey literature sources up to 7 February 2020. Randomised controlled trials and non-randomised studies of interventions were eligible for inclusion. The search returned 28,846 records, of which 10 studies on recombinant HA influenza vaccine met our inclusion criteria. One study found that the quadrivalent recombinant HA influenza vaccine had higher relative vaccine efficacy (rVE) in preventing laboratory-confirmed influenza during the 2014-15 season compared with traditional quadrivalent vaccination in adults aged ≥50 years (rVE = 30%, 95% CI 10%-47%, moderate-certainty evidence). In a subgroup analysis, higher rVE was reported for influenza A (rVE = 36%, 95% CI 14% to 53%), but not for B (non-significant). Another study reported higher efficacy for the trivalent recombinant HA vaccine compared with placebo (VE = 45%, 95% CI 19-63, 1 RCT, low-certainty evidence) in adults aged 18-55 years. With the exception of a higher rate of chills (RR = 1.33, 95% CI 1.03-1.72), the safety profile of recombinant HA vaccines was comparable to that of traditional influenza vaccines. The evidence base for the efficacy and effectiveness of recombinant HA influenza vaccines is limited at present, although one study found that the quadrivalent recombinant HA influenza vaccine had higher rVE compared with traditional quadrivalent vaccination in adults aged ≥50 years.

Interpretation of Relative Efficacy and Effectiveness for Influenza Vaccines

Relative vaccine effectiveness (rVE) are metrics commonly reported to compare absolute VE (aVE) of two vaccine products. Estimates of rVE for enhanced influenza vaccines (eIV) vs. standard inactivated influenza vaccine (IIV) have been assessed across different seasons, influenza-specific endpoints, and nonspecific endpoints (e.g., all-cause cardiovascular hospitalizations). To illustrate the challenges of comparability across studies, we conducted a scenario analysis to evaluate the effects of varying absolute VE (aVE) of IIV (i.e., as compared with placebo) on the interpretation of rVE of eIV vs IIV. We show that estimates of rVE might not be comparable across studies because additional benefits commensurate with a given estimate of rVE are dependent on the aVE for the comparator vaccine, which can depend on factors such as host response to vaccine, virus type, and clinical endpoint evaluated. These findings have implications for interpretation of rVE across studies and for sample size considerations in future trials.

A broad influenza virus inhibitor acting via IMP dehydrogenase and in synergism with ribavirin

To suppress serious influenza infections in persons showing insufficient protection from the vaccines, antiviral drugs are of vital importance. There is a need for novel agents with broad activity against influenza A (IAV) and B (IBV) viruses and with targets that differ from those of the current antivirals. We here report a new small molecule influenza virus inhibitor referred to as CPD A (chemical name: N-(pyridin-3-yl)thiophene-2-carboxamide). In an influenza virus minigenome assay, this non-nucleoside compound inhibited RNA synthesis of IAV and IBV with EC₅₀ values of 2.3 μM and 2.6 μM, respectively. Robust in vitro activity was noted against a broad panel of IAV (H1N1 and H3N2) and IBV strains, with a median EC₅₀ value of 0.20 μM, which is 185-fold below the 50% cytotoxic concentration. The action point in the viral replication cycle was located between 1 and 5 h p.i., showing a similar profile as ribavirin. Like this nucleoside analogue, CPD A was shown to cause strong depletion of the cellular GTP pool and, accordingly, its antiviral activity was antagonized when this pool was restored with exogenous guanosine. This aligns with the observed inhibition in a cell-based IMP dehydrogenase (IMPDH) assay, which seems to require metabolic activation of CPD A since no direct inhibition was seen in an enzymatic IMPDH assay. The combination of CPD A with ribavirin, another IMPDH inhibitor, proved strongly synergistic. To conclude, we established CPD A as a new inhibitor of influenza A and B virus replication and RNA synthesis, and support the potential of IMPDH inhibitors for influenza therapy with acceptable safety profile.

Exploration of the 2,3-dihydroisoindole pharmacophore for inhibition of the influenza virus PA endonuclease

Seasonal influenza A and B viruses represent a global concern. Antiviral drugs are crucial to treat severe influenza in high-risk patients and prevent virus spread in case of a pandemic. The emergence of viruses showing drug resistance, in particular for the recently licensed polymerase inhibitor baloxavir marboxil, drives the need for developing alternative antivirals. The endonuclease activity residing in the N-terminal domain of the polymerase acidic protein (PA_N) is crucial for viral RNA synthesis and a validated target for drug design. Its function can be impaired by molecules bearing a metal-binding pharmacophore (MBP) able to coordinate the two divalent metal ions in the active site. In the present work, the 2,3-dihydro-6,7-dihydroxy-1H-isoindol-1-one scaffold is explored for the inhibition of influenza virus PA endonuclease. The structure-activity relationship was analysed by modifying the substituents on the lipophilic moiety linked to the MBP. The new compounds exhibited nanomolar inhibitory activity in a FRET-based enzymatic assay, and a few compounds (15-17, 21) offered inhibition in the micromolar range, in a cell-based influenza virus polymerase assay. When investigated against a panel of PA-mutant forms, compound 17 was shown to retain full activity against the baloxavir-resistant I38T mutant. This was corroborated by docking studies providing insight into the binding mode of this novel class of PA inhibitors.

Review of Influenza Virus Vaccines: The Qualitative Nature of Immune Responses to Infection and Vaccination Is a Critical Consideration

Influenza viruses have affected the world for over a century, causing multiple pandemics. Throughout the years, many prophylactic vaccines have been developed for influenza; however, these viruses are still a global issue and take many lives. In this paper, we review influenza viruses, associated immunological mechanisms, current influenza vaccine platforms, and influenza infection, in the context of immunocompromised populations. This review focuses on the qualitative nature of immune responses against influenza viruses, with an emphasis on trained immunity and an assessment of the characteristics of the host–pathogen that compromise the effectiveness of immunization. We also highlight innovative immunological concepts that are important considerations for the development of the next generation of vaccines against influenza viruses.

Implementation of a program to improve influenza vaccination rates among medical students: a comparative study involving two university affiliated hospitals

Background and objectives: Influenza vaccination rates among medical students (MSs) are below the standards recommended in hospitals where influenza vaccination is not mandatory. We carried out a comparative study in two Spanish university hospitals to reassert this fact and evaluated the impact on vaccination rates of a specific program aimed at promoting influenza vaccination among MSs.Methods: A descriptive cross-sectional study was performed describing influenza vaccination rates and motivations for vaccination during the 2017/18 campaign among MSs in two hospitals affiliated to the same university. We subsequently performed a community-based intervention study during the 2018/19 campaign evaluating the impact of a strategy for promoting influenza vaccination, comparing the hospital where the intervention took place (hospital A) with the one where it did not take place (hospital B).Results: During de 2017/18 campaign the overall influenza vaccination rate was 44.8%, with no differences between hospitals A and B (difference: 3.9%; 95% CI: -4.36-12.16; p-value = .4). During the 2018/19 campaign, vaccination rate increased to 76.4% in hospital A, with significant differences compared with the previous campaign in the same hospital (29.8%; OR 5.00; 95% CI: 3.14-8.3; p-value = .0001) and with that observed in hospital B in the same campaign (21.1%; 95% CI: 13.38-28.82; p-value <.001).Conclusions: Influenza vaccination rates among MSs in two Spanish university affiliated hospitals were below the recommended standards. A new reproducible strategy for promoting influenza vaccination with a specific approach toward MSs achieved a significant improvement in vaccination rate.

Cost-effectiveness of childhood influenza vaccination in Europe: results from a systematic review

Introduction: Influenza can be a significant public health problem. Nevertheless, it is preventable through vaccination. Concerning the pediatric population, the recommendation of influenza vaccination is under-represented in many European countries. The aim of this systematic review is to evaluate the cost-effectiveness of universal childhood vaccination against influenza in Europe.Areas covered: We conducted a systematic review of original article assessing the cost-effectiveness of influenza vaccination by searching PubMed, Embase and Scopus databases for studies in English, starting from January 1^st, 2010 up to October 21^st, 2020.Expert opinion: Our literature review showed that all studies identified highlight that pediatric vaccinations using a live vaccine, especially in the quadrivalent formulation, are cost-effective compared to current vaccinations (elderly and at-risk groups) with TIV or no vaccination. A significant contribution to this positive economic profile is due to the indirect protection. Already many clinical data report the relevant direct and indirect impact of vaccination against influenza for younger subjects. The recent studies collected in this review showed also that the pediatric vaccination is also cost-effective. Therefore, decision-makers should now consider this new favorable evidence.

Oseltamivir and the Risk of Neuropsychiatric Events: A National, Population-based Study

BACKGROUND

Reports of serious neuropsychiatric events (NPEs), specifically suicide/suicide attempts, following the use of oseltamivir have led to public concerns. Our aim in this study was to determine whether an association exists between oseltamivir use and NPEs.

METHOD

This study was a population-based, retrospective, cohort study on a random sample of 50% of individuals in the Korean National Health Insurance Service (KNIS) database aged ≥8 years who were diagnosed with influenza between 2009 and 2017. The primary exposure was oseltamivir prescription at the time of influenza diagnosis, whereas the primary outcome was a diagnosis of an NPE within 30 days after the influenza diagnosis. Information on oseltamivir prescription, diagnoses of NPEs, demographic characteristics, comorbidities, drugs prescribed within the year before influenza diagnosis, and healthcare utilization were extracted from the KNIS database.

RESULTS

Of 3 352 015 individuals included in the analysis, 1 266 780 (37.8%) were prescribed oseltamivir. The incidence of NPEs was 0.86% and 1.16% in patients who were and were not prescribed oseltamivir, respectively (hazard ratio [HR], 0.74; 95% confidence interval [CI], .73 to .75; P < .001). Oseltamivir use was not associated with a difference in the overall risk of NPEs in the adjusted model (HR, 0.98; 95% CI, .96 to 1.01; P = .16), but the incidence of moderate-to-severe NPEs was significantly lower in those prescribed oseltamivir (HR, 0.92; 95% CI, .88-.96; P < .001).

CONCLUSION

Treating influenza with oseltamivir does not increase the risk of NPEs. Thus, public concern regarding its use is unwarranted.

Tandem high-dose influenza vaccination is associated with more durable serologic immunity in patients with plasma cell dyscrasias

Patients with plasma cell dyscrasias (PCDs) experience an increased burden of influenza, and current practice of single-dose annual influenza vaccination yields suboptimal protective immunity in these patients. Strategies to improve immunity to influenza in these patients are clearly needed. We performed a randomized, double-blind, placebo-controlled clinical trial comparing tandem Fluzone High-Dose influenza vaccination with standard-of-care influenza vaccination. Standard-of-care vaccination was single-dose age-based vaccination (standard dose, <65 years; high dose, ≥65 years), and patients in this arm received a saline placebo injection at 30 days. A total of 122 PCD patients were enrolled; 47 received single-dose standard-of-care vaccination, and 75 received 2 doses of Fluzone High-Dose vaccine. Rates of hemagglutinin inhibition (HAI) titer seroprotection against all 3 strains (H1N1, H3N2, and influenza B) were significantly higher for patients after tandem high-dose vaccination vs control (87.3% vs 63.2%; P = .003) and led to higher seroprotection at the end of flu season (60.0% vs 31.6%; P = .04). These data demonstrate that tandem high-dose influenza vaccination separated by 30 days leads to higher serologic HAI titer responses and more durable influenza-specific immunity in PCD patients. Similar vaccine strategies may also be essential to achieve protective immunity against other emerging pathogens such as novel coronavirus in these patients. This trial was registered at www.clinicaltrials.gov as #NCT02566265.

Seasonal and pandemic influenza: 100 years of progress, still much to learn

Influenza viruses are highly transmissible, both within and between host species. The severity of the disease they cause is highly variable, from the mild and inapparent through to the devastating and fatal. The unpredictability of epidemic and pandemic outbreaks is accompanied but the predictability of seasonal disease in wide areas of the Globe, providing an inexorable toll on human health and survival. Although there have been great improvements in understanding influenza viruses and the disease that they cause, our knowledge of the effects they have on the host and the ways that the host immune system responds continues to develop. This review highlights the importance of the mucosa in defence against infection and in understanding the pathogenesis of disease. Although vaccines have been available for many decades, they remain suboptimal in needing constant redesign and in only providing short-term protection. There are real prospects for improvement in treatment and prevention of influenza soon, based on deeper knowledge of how the virus transmits, replicates and triggers immune defences at the mucosal surface.

Early Bird Gets the Flu: What Should Be Done About Waning Intraseasonal Immunity Against Seasonal Influenza?

Recently published studies highlight the growing evidence for waning immunity within a single influenza season among vaccinated individuals. However, the public health efforts to increase vaccination coverage has resulted in earlier administration of vaccines. We find this approach to be suboptimal, as the benefits of early vaccination could be lost during peak months of influenza activity. Immunity generated by influenza vaccines is a complex scientific issue with many contributing factors. We advocate for a nuanced approach to the seasonal vaccine program- one that considers duration of immunity as much as it considers coverage. As we strive for higher rates of vaccination, we must also improve the efficacy of the vaccine and the public health programs that are responsible for distributing and administering the vaccine.

Large-scale influenza vaccination promotion on a mobile app platform: A randomized controlled trial

While health-care providers have used incentives in an attempt to motivate patients to obtain vaccinations, their effect on vaccination rates has not been systematically evaluated on a large scale. In this study, we examined whether mobile applications may improve population vaccination rates through enhanced communication and incentives education. Our study is the first randomized controlled trial assessing the effect of large-scale messaging combined with individualized incentives on influenza-vaccination rates. In this trial, we delivered messages regarding influenza vaccinations to 50,286 adults, aged 18 through 65, then compared the subsequent vaccination rate, the effectiveness of the message content and the timing. Multiple rounds of messaging occurred over a seven-week period during the 2016 flu season, after which vaccination rates were observed for one week. Participants were randomly assigned to one of three messaging approaches: conspicuous (highlighting the amount of rewards to be received for obtaining a flu shot); generic (promoting vaccinations with no mention of rewards); or no-message. Evidence of vaccination obtainment was indicated by medical and pharmacy claims, augmented by patients self-reporting through the mobile wellness app during the study period. Of the people assigned to receive messaging, 23.2% obtained influenza vaccination, compared to 22.0% of people who obtained vaccination in the no-messaging control arm. This difference was statistically significant (p < 0.01). The research revealed that messaging effectiveness decreased after each successive batch sent, suggesting that most participants responsive to messaging would become activated immediately after receiving one alert. Interestingly, in this large-scale study, there were no significant differences between conspicuous incentives and generic messaging, suggesting an important area for future research. Trial Registration: clinicaltrials.gov identifier: NCT02908893.

Fc functional antibody responses to adjuvanted versus unadjuvanted seasonal influenza vaccination in community-dwelling older adults

BACKGROUND

Seasonal influenza vaccination with a standard trivalent influenza vaccine (TIV) induces a modest, and cross-reactive, Fc functional antibody response in older adults. Recent improvements to influenza vaccines include a quadrivalent influenza vaccine (QIV) and a TIV adjuvanted with the squalene-based oil-in-water emulsion MF59.

METHODS

Pre- and post-vaccination serum samples from older adults vaccinated with QIV (n = 27) and adjuvanted TIV (n = 44) were studied using hemagglutination inhibition (HAI) assays and dimeric Fc-gamma receptor IIIa binding ELISAs, as a surrogate of antibody-dependent cellular cytotoxicity (ADCC).

RESULTS

We found that the unadjuvanted QIV elicited a stronger HAI response against the H1N1 vaccine virus than the adjuvanted TIV. Post-vaccination levels of HA-specific ADCC antibodies were similar for older adults vaccinated with QIV and adjuvanted TIV. The ADCC response to influenza vaccination was largely determined by pre-vaccination or baseline levels of these antibodies, with older adults with low baseline levels of ADCC activity demonstrating greater post-vaccination rises.

CONCLUSIONS

In this cohort of community-dwelling older adults, the QIV was at least as good as the adjuvanted TIV in the induction of ADCC and HAI responses. Further studies on how these antibody responses translate to efficacy in preventing influenza infections are warranted.

Enhanced Passive Safety Surveillance (EPSS) confirms an optimal safety profile of the use of MF59® -adjuvanted influenza vaccine in older adults: Results from three consecutive seasons

BACKGROUND

In Europe, the enhanced safety surveillance (ESS) of seasonal influenza vaccines is mandatory, in order to detect any potential increase in reactogenicity when the vaccine composition is updated. The MF59® -adjuvanted influenza vaccine (Fluad™) is the first and the only licensed adjuvanted seasonal influenza vaccine in Europe.

OBJECTIVE

Our objective was to summarize the safety data of Fluad™ over three consecutive seasons.

METHODS

A passive approach to ESS (EPSS) was adopted, in which reporting of spontaneous adverse events (AEs) by vaccinees and vaccine exposure was estimated, in order to generate a near real-time reporting rate. EPSS was conducted in Italy during the 2015, 2016, and 2017 influenza seasons in the primary care setting. All AEs reported within 7 days following immunization were analyzed by season, type and seriousness. Fisher's exact test was used to compare frequencies between seasons.

RESULTS

Total exposure accounted for approximately 1,000 doses of Fluad™ for each season. A total of 0.5% (2015), 0.7% (2016), and 0.5% (2017) individual case safety reports (ICSRs) were received, corresponding to a total of 9 (2015), 18 (2016), and 12 (2017) spontaneous AEs. The frequencies of AEs of interest were below those expected on the basis of the known safety profile of the vaccine. Most AEs were mild-to-moderate in severity. No between-season difference was found.

CONCLUSIONS

Our analyses confirmed that the safety data observed were consistent with the known safety profile of Fluad™, which has been amply established over the last 20 years. No significant changes in the safety profile were observed.

Peptide Epitope Hot Spots of CD4 T Cell Recognition Within Influenza Hemagglutinin During the Primary Response to Infection

Antibodies specific for the hemagglutinin (HA) protein of influenza virus are critical for protective immunity to infection. Our studies show that CD4 T cells specific for epitopes derived from HA are the most effective in providing help for the HA-specific B cell responses to infection and vaccination. In this study, we asked whether HA epitopes recognized by CD4 T cells in the primary response to infection are equally distributed across the HA protein or if certain segments are enriched in CD4 T cell epitopes. Mice that collectively expressed eight alternative MHC (Major Histocompatibility Complex) class II molecules, that would each have different peptide binding specificities, were infected with an H1N1 influenza virus. CD4 T cell peptide epitope specificities were identified by cytokine EliSpots. These studies revealed that the HA-specific CD4 T cell epitopes cluster in two distinct regions of HA and that some segments of HA are completely devoid of CD4 T cell epitopes. When located on the HA structure, it appears that the regions that most poorly recruit CD4 T cells are sequestered within the interior of the HA trimer, perhaps inaccessible to the proteolytic machinery inside the endosomal compartments of antigen presenting cells.

Hospitalization and death among patients with influenza, Guatemala, 2008-2012

Background

Influenza is a major cause of respiratory illness resulting in 3–5 million severe cases and 291,243-645,832 deaths annually. Substantial health and financial burden may be averted by annual influenza vaccine application, especially for high risk groups.

Methods

We used an active facility-based surveillance platform for acute respiratory diseases in three hospitals in Guatemala, Central America, to estimate the incidence of laboratory-confirmed hospitalized influenza cases and identify risk factors associated with severe disease (defined as admission to the intensive care unit (ICU) or death). We enrolled patients presenting with signs and symptoms of acute respiratory infection (ARI) and obtained naso- and oropharyngeal samples for real-time reverse transcriptase polymerase chain reaction (RT-PCR). We used multivariable logistic regression to identify risk factors for ICU admission or death, adjusted for age and sex.

Results

From May 2008 to July 2012, among 6326 hospitalized ARI cases, 446 (7%) were positive for influenza: of those, 362 (81%) had influenza A and 84 (18%) had influenza B. Fifty nine percent of patients were aged ≤ 5 years, and 10% were aged ≥ 65 years. The median length of hospitalization was 5 days (interquartile range: 5). Eighty of 446 (18%) were admitted to the ICU and 28 (6%) died. Among the 28 deaths, 7% were aged ≤ 6 months, 39% 7–60 months, 21% 5–50 years, and 32% ≥ 50 years. Children aged ≤ 6 months comprised 19% of cases and 22% of ICU admissions. Women of child-bearing age comprised 6% of cases (2 admitted to ICU; 1 death). In multivariable analyses, Santa Rosa site (adjusted odds ratio [aOR] = 10, 95% confidence interval [CI] = 2–50), indigenous ethnicity (aOR = 4, 95% CI = 2–13, and radiologically-confirmed pneumonia (aOR = 5, 95% CI = 3–11) were independently associated with severe disease. Adjusted for hospital utilization rate, annual incidence of hospitalized laboratory-confirmed influenza was 24/100,000 overall, 93/100,000 for children aged < 5 years and 50/100,000 for those ≥ 65 years.

Conclusions

Influenza is a major contributor of hospitalization and death due to respiratory diseases in Guatemala. Further application of proven influenza prevention and treatment strategies is warranted.

Antibody-Dependent Cellular Cytotoxicity Responses to Seasonal Influenza Vaccination in Older Adults

Background

Older adults are at high risk of influenza disease, but generally respond poorly to vaccination. Antibody-dependent cellular cytotoxicity (ADCC) may be an important component of protection against influenza infection. An improved understanding of the ADCC response to influenza vaccination in older adults is required.

Methods

We studied sera samples from 3 groups of subjects aged ≥65 years (n = 16-17/group) receiving the 2008/2009 seasonal trivalent influenza vaccine (TIV). Subjects had minimal pre-existing hemagglutination inhibiting (HAI) antibodies and TIV induced either no, low, or high HAI responses. Serum ADCC activity was analyzed using Fc receptor cross-linking, NK cell activation, and influenza-infected cell killing.

Results

Most subjects from TIV nonresponder, low responder, and high responder groups had detectable ADCC antibodies prevaccination, but baseline ADCC was not predictive of HAI vaccine responsiveness. Interestingly, ADCC and HAI responses tracked closely across all groups, against all 3 TIV hemagglutinins, and in all ADCC assays tested.

Conclusions

Older adults commonly have pre-existing ADCC antibodies in the absence of high HAI titers to circulating influenza strains. In older vaccinees, ADCC response mirrored HAI antibodies and was readily detectable despite high postvaccination HAI titers. Alternate measures of vaccine responsiveness and improved vaccinations in this at-risk group are needed.

Use of adjuvanted trivalent influenza vaccine in older-age adults: a systematic review of economic evidence

Seasonal influenza is a very common disease. Yearly vaccination of at-risk population groups is a well-recognized cost-effective/cost-saving preventive measure. It is, however, unclear which available alternative has the most favorable economic profile. Some available options are: trivalent (TIV) and quadrivalent (QIV) inactivated vaccines, adjuvanted TIV (aTIV). Because of immunosenescence, aTIV has been specifically developed for elderly. The present study aimed at assessing the available evidence of aTIV use in elderly from the economic perspective. A systematic literature review targeting aTIV economic evaluations in adults aged ≥65 years was performed using Medline via Ovid, Embase, DARE and NHS/EED. Of a total of 3,654 papers screened, 18 studies (13 full papers, 5 conference abstracts) were included. It emerged that compared with both non-vaccination or non-adjuvanted vaccines, aTIV was cost-effective or cost-saving. The vaccinations strategies incorporating aTIV based on age and/or risk profile are associated with the most favorable economic outcomes.

Evolution and Biological Evaluation of Matrinic Derivatives with Amantadine Fragments As New Anti-Influenza Virus Agents

A series of novel tricyclic matrinic derivatives with 11-adamantyl substitution were designed, synthesized, and evaluated for their activities against Influenza A H3N2 virus, based on the privileged structure strategy. Structure-activity relationship (SAR) analysis indicated that the introduction of an 11-adamantyl might be helpful for the potency. Among them, compounds 9f and 9j exhibited the promising anti-H3N2 activities with IC50 values of 7.2 μM and 10.2 μM, respectively, better than that of lead 1. Their activities were further confirmed at the protein level. Moreover, compound 9f displayed a high pharmacokinetic (PK) stability profile in whole blood and a safety profile in vivo. In primary mechanism, compound 9f could inhibit the virus replication cycle at early stage by targeting M2 protein, consistent with that of the parent amantadine. This study provided powerful information for further strategic optimization to develop these compounds into a new class of anti-influenza agents.

Influenza virus entry via the GM3 ganglioside-mediated platelet-derived growth factor receptor β signalling pathway

The possible resistance of influenza virus against existing antiviral drugs calls for new therapeutic concepts. One appealing strategy is to inhibit virus entry, in particular at the stage of internalization. This requires a better understanding of virus-host interactions during the entry process, including the role of receptor tyrosine kinases (RTKs). To search for cellular targets, we evaluated a panel of 276 protein kinase inhibitors in a multicycle antiviral assay in Madin-Darby canine kidney cells. The RTK inhibitor Ki8751 displayed robust anti-influenza A and B virus activity and was selected for mechanistic investigations. Ki8751 efficiently disrupted the endocytic process of influenza virus in different cell lines carrying platelet-derived growth factor receptor β (PDGFRβ), an RTK that is known to act at GM3 ganglioside-positive lipid rafts. The more efficient virus entry in CHO-K1 cells compared to the wild-type ancestor (CHO-wt) cells indicated a positive effect of GM3, which is abundant in CHO-K1 but not in CHO-wt cells. Entering virus localized to GM3-positive lipid rafts and the PDGFRβ-containing endosomal compartment. PDGFRβ/GM3-dependent virus internalization involved PDGFRβ phosphorylation, which was potently inhibited by Ki8751, and desialylation of activated PDGFRβ by the viral neuraminidase. Virus uptake coincided with strong activation of the Raf/MEK/Erk cascade, but not of PI3K/Akt or phospholipase C-γ. We conclude that influenza virus efficiently hijacks the GM3-enhanced PDGFRβ signalling pathway for cell penetration, providing an opportunity for host cell-targeting antiviral intervention.

Excess Deaths Attributable to Influenza-Like Illness in the ESRD Population

BACKGROUND

Morbidity and mortality vary seasonally. Timing and severity of influenza seasons contribute to those patterns, especially among vulnerable populations such as patients with ESRD. However, the extent to which influenza-like illness (ILI), a syndrome comprising a range of potentially serious respiratory tract infections, contributes to mortality in patients with ESRD has not been quantified.

METHODS

We used data from the Centers for Disease Control and Prevention (CDC) Outpatient Influenza-like Illness Surveillance Network and Centers for Medicare and Medicaid Services ESRD death data from 2000 to 2013. After addressing the increasing trend in deaths due to the growing prevalent ESRD population, we calculated quarterly relative mortality compared with average third-quarter (summer) death counts. We used linear regression models to assess the relationship between ILI data and mortality, separately for quarters 4 and 1 for each influenza season, and model parameter estimates to predict seasonal mortality counts and calculate excess ILI-associated deaths.

RESULTS

An estimated 1% absolute increase in quarterly ILI was associated with a 1.5% increase in relative mortality for quarter 4 and a 2.0% increase for quarter 1. The average number of annual deaths potentially attributable to ILI was substantial, about 1100 deaths per year.

CONCLUSIONS

We found an association between community ILI activity and seasonal variation in all-cause mortality in patients with ESRD, with ILI likely contributing to >1000 deaths annually. Surveillance efforts, such as timely reporting to the CDC of ILI activity within dialysis units during influenza season, may help focus attention on high-risk periods for this vulnerable population.

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.

Providing Additional "Muscle" for Older Adults Through Optimal Influenza Vaccine Selection

Immunization is the best strategy to protect individuals from influenza; however, older adults tend to respond less favorably to vaccines because of immunosenescence. The Centers for Disease Control and Prevention states that any licensed, recommended, and age-appropriate influenza vaccine may be used in older adults despite reasonable evidence suggesting that the high-dose and, to a lesser extent, the adjuvanted and recombinant influenza vaccines provide better protection than the standard-dose vaccines in this vulnerable population. In this era of precision medicine, clinicians can preferentially recommend these contemporary vaccines to equip their older patients with the best possible protection against influenza.

Influenza vaccine showed a good preventive effect against influenza-associated hospitalization among elderly patients, during the 2016/17 season in Japan

The 2016/17 influenza season in Japan was characterized by a predominance of influenza A (H3N2) activity; with H3N2 accounting for 85% of all detected influenza virus infections. We assessed the vaccine effectiveness (VE) of an inactivated quadrivalent influenza vaccine (IIV4) in adult patients, using a test-negative case-control design study based on the results of a rapid influenza diagnostic test (RIDT). Between November 2016 and March 2017, a total of 1048 adult patients were enrolled: including 363 RIDT positive for influenza A, 9 RIDT-positive for influenza B, and 676 RIDT-negative. During the 2016/17 season, the overall adjusted VE was 28.8% (95% confidence interval [CI]: 6.3-46%). The adjusted VE against influenza A was 27.4% (95%CI: 4.4-45%). The VE against influenza B could not be estimated because of the very low number of influenza B patients. Twenty-nine patients were hospitalized due to influenza-associated illness-during the present study, all of whom were infected with influenza A virus. The adjusted VE, determined using a case-control study, for preventing hospitalization for influenza A infection was 72.6% (95%CI: 30.7-89.1%). In addition, the VE for preventing hospitalization of influenza patients with comorbidities was 78.2% (95%CI: 41.1-92%). Our study showed that, during the 2016/17season, IIV4 was effective for preventing both the onset of influenza and influenza-associated hospitalization.

Influenza vaccination of cancer patients during PD-1 blockade induces serological protection but may raise the risk for immune-related adverse events

Background

Immune checkpoint inhibiting antibodies were introduced into routine clinical practice for cancer patients. Checkpoint blockade has led to durable remissions in some patients, but may also induce immune-related adverse events (irAEs). Lung cancer patients show an increased risk for complications, when infected with influenza viruses. Therefore, vaccination is recommended. However, the efficacy and safety of influenza vaccination during checkpoint blockade and its influence on irAEs is unclear. Similarly, the influence of vaccinations on T cell-mediated immune reactions in patients during PD-1 blockade remains poorly defined.

Methods

We vaccinated 23 lung cancer patients and 11 age-matched healthy controls using a trivalent inactivated influenza vaccine to investigate vaccine-induced immunity and safety during checkpoint blockade.

Results

We did not observe significant differences between patients and healthy controls in vaccine-induced antibody titers against all three viral antigens. Influenza vaccination resulted in protective titers in more than 60% of patients/participants. In cancer patients, the post-vaccine frequency of irAEs was 52.2% with a median time to occurrence of 3.2 months after vaccination. Six of 23 patients (26.1%) showed severe grade 3/4 irAEs. This frequency of irAEs might be higher than the rate previously published in the literature and the rate observed in a non-study population at our institution (all grades 25.5%, grade 3/4 9.8%).

Conclusions

Although this is a non-randomized trial with a limited number of patients, the increased rate of immunological toxicity is concerning. This finding should be studied in a larger patient population.