Influenza

Predicting influenza-like illness trends based on sentinel surveillance data in China from 2011 to 2019: A modelling and comparative study1

Background

Influenza is an acute respiratory infectious disease with a significant global disease burden. Additionally, the coronavirus disease 2019 pandemic and its related non-pharmaceutical interventions (NPIs) have introduced uncertainty to the spread of influenza. However, comparative studies on the performance of innovative models and approaches used for influenza prediction are limited. Therefore, this study aimed to predict the trend of influenza-like illness (ILI) in settings with diverse climate characteristics in China based on sentinel surveillance data using three approaches and evaluate and compare their predictive performance.

Methods

The generalized additive model (GAM), deep learning hybrid model based on Gate Recurrent Unit (GRU), and autoregressive moving average-generalized autoregressive conditional heteroscedasticity (ARMA-GARCH) model were established to predict the trends of ILI 1-, 2-, 3-, and 4-week-ahead in Beijing, Tianjin, Shanxi, Hubei, Chongqing, Guangdong, Hainan, and the Hong Kong Special Administrative Region in China, based on sentinel surveillance data from 2011 to 2019. Three relevant metrics, namely, Mean Absolute Percentage Error (MAPE), Root Mean Squared Error (RMSE), and R squared, were calculated to evaluate and compare the goodness of fit and robustness of the three models.

Results

Considering the MAPE, RMSE, and R squared values, the ARMA-GARCH model performed best, while the GRU-based deep learning hybrid model exhibited moderate performance and GAM made predictions with the least accuracy in the eight settings in China. Additionally, the models' predictive performance declined as the weeks ahead increased. Furthermore, blocked cross-validation indicated that all models were robust to changes in data and had low risks of overfitting.

Conclusions

Our study suggested that the ARMA-GARCH model exhibited the best accuracy in predicting ILI trends in China compared to the GAM and GRU-based deep learning hybrid model. Therefore, in the future, the ARMA-GARCH model may be used to predict ILI trends in public health practice across diverse climatic zones, thereby contributing to influenza control and prevention efforts.

AMG487 alleviates influenza A (H1N1) virus-induced pulmonary inflammation through decreasing IFN-γ-producing lymphocytes and IFN-γ concentrations

BACKGROUND AND PURPOSE

Severe influenza virus-infected patients have high systemic levels of Th1 cytokines (including IFN-γ). Intrapulmonary IFN-γ increases pulmonary IFN-γ-producing T lymphocytes through the CXCR3 pathway. Virus-infected mice lacking IP-10/CXCR3 demonstrate lower pulmonary neutrophilic inflammation. AMG487, an IP-10/CXCR3 antagonist, ameliorates virus-induced lung injury in vivo through decreasing viral loads. This study examined whether AMG487 could treat H1N1 virus-induced mouse illness through reducing viral loads or decreasing the number of lymphocytes or neutrophils.

EXPERIMENTAL APPROACH

Here, we studied the above-mentioned effects and underlying mechanisms in vivo.

KEY RESULTS

H1N1 virus infection caused bad overall condition and pulmonary inflammation characterized by the infiltration of lymphocytes and neutrophils. From Day-5 to Day-10 post-virus infection, bad overall condition, pulmonary lymphocytes, and IFN-γ concentrations increased, while pulmonary H1N1 viral titres and neutrophils decreased. Both anti-IFN-γ and AMG487 alleviated virus infection-induced bad overall condition and pulmonary lymphocytic inflammation. Pulmonary neutrophilic inflammation was mitigated by AMG487 on Day-5 post-infection, but was not mitigated by AMG487 on Day-10 post-infection. H1N1 virus induced increases of IFN-γ, IP-10, and IFN-γ-producing lymphocytes and activation of the Jak2-Stat1 pathways in mouse lungs, which were inhibited by AMG487. Anti-IFN-γ decreased IFN-γ and IFN-γ-producing lymphocytes on Day-5 post-infection. AMG487 but not anti-IFN-γ decreased viral titres in mouse lung homogenates or BALF. Higher virus load did not increase pulmonary inflammation and IFN-γ concentrations when mice were treated with AMG487.

CONCLUSION AND IMPLICATIONS

AMG487 may ameliorate H1N1 virus-induced pulmonary inflammation through decreasing IFN-γ-producing lymphocytes rather than reducing viral loads or neutrophils.

Molecular surveillance of influenza A virus in Saudi Arabia: whole-genome sequencing and metagenomic approaches

Outbreaks of influenza A viruses are generally seasonal and cause annual epidemics worldwide. Due to their frequent reassortment and evolution, annual surveillance is of paramount importance to guide vaccine strategies. The aim of this study was to explore the molecular epidemiology of influenza A virus and nasopharyngeal microbiota composition in infected patients in Saudi Arabia. A total of 103 nasopharyngeal samples from 2015 and 12 samples from 2022 were collected from patients positive for influenza A. Sequencing of influenza A as well as metatranscriptomic analysis of the nasopharyngeal microbiota was conducted using Oxford Nanopore sequencing. Phylogenetic analysis of hemagglutinin, neuraminidase segments, and concatenated influenza A genomes was performed using MEGA7. Whole-genome sequencing analysis revealed changing clades of influenza A virus: from 6B.1 in 2015 to 5a.2a in 2022. One sample containing the antiviral resistance-mediating mutation S247N toward oseltamivir and zanamivir was found. Phylogenetic analysis showed the clustering of influenza A strains with the corresponding vaccine strains in each period, thus suggesting vaccine effectiveness. Principal component analysis and alpha diversity revealed the absence of a relationship between hospital admission status, age, or gender of infected patients and the nasopharyngeal microbial composition, except for the infecting clade 5a.2a. The opportunistic pathogens Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis were the most common species detected. The molecular epidemiology appears to be changing in Saudi Arabia after the COVID-19 pandemic. Antiviral resistance should be carefully monitored in future studies. In addition, the disease severity of patients as well as the composition of the nasopharyngeal microbiota in patients infected with different clades should also be assessed.IMPORTANCEIn this work, we have found that the clade of influenza A virus circulating in Riyadh, KSA, has changed over the last few years from 6B.1 to 5a.2a. Influenza strains clustered with the corresponding vaccine strains in our population, thus emphasizing vaccine effectiveness. Metatranscriptomic analysis showed no correlation between the nasopharyngeal microbiome and the clinical and/or demographic characteristics of infected patients. This is except for the 5a.2a strains isolated post-COVID-19 pandemic. The influenza virus is among the continuously evolving viruses that can cause severe respiratory infections. Continuous surveillance of its molecular diversity and the monitoring of anti-viral-resistant strains are thus of vital importance. Furthermore, exploring potential microbial markers and/or dysbiosis of the nasopharyngeal microbiota during infection could assist in the better management of patients in severe cases.

Novel Acyl Thiourea-Based Hydrophobic Tagging Degraders Exert Potent Anti-Influenza Activity through Two Distinct Endonuclease Polymerase Acidic-Targeted Degradation Pathways

The spread of the influenza virus has caused devastating pandemics and huge economic losses worldwide. Antiviral drugs with diverse action modes are urgently required to overcome the challenges of viral mutation and drug resistance, and targeted protein degradation strategies constitute excellent candidates for this purpose. Herein, the first degradation of the influenza virus polymerase acidic (PA) protein using small-molecule degraders developed by hydrophobic tagging (HyT) technology to effectively combat the influenza virus was reported. The SAR results revealed that compound 19b with Boc2-(L)-Lys demonstrated excellent inhibitory activity against A/WSN/33/H1N1 (EC50 = 0.015 μM) and amantadine-resistant strain (A/PR/8/H1N1), low cytotoxicity, high selectivity, substantial degradation ability, and good drug-like properties. Mechanistic studies demonstrated that the proteasome system and autophagic lysosome pathway were the potential drivers of these HyT degraders. Thus, this study provides a powerful tool for investigating the targeted degradation of influenza virus proteins and for antiviral drug development.

Morpholinodiazenyl chalcone blocks influenza A virus capsid uncoating by perturbing the clathrin-mediated vesicular trafficking pathway

Influenza A virus (IAV) is a highly contagious respiratory pathogen that significantly threatens global health by causing seasonal epidemics and occasional, unpredictable pandemics. To identify new compounds with therapeutic potential against IAV, we designed and synthesized a series of 4'-morpholinodiazenyl chalcones using the molecular hybridization method, performed a high-content screen against IAV, and found that (E)-1-{4-[(E)-morpholinodiazenyl]phenyl}-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (MC-22) completely neutralized IAV infection. While MC-22 allowed IAV to successfully internalize into the cell and fuse at the acidic late endosomes, it prevented viral capsid uncoating and genome release. Since IAV majorly utilizes clathrin-mediated endocytosis (CME) for cellular entry, we examined whether MC-22 had any effect on CME, using nonviral cargoes that enter cells via clathrin-dependent or -independent pathways. Although MC-22 showed no effect on the uptake of choleratoxin B, a cargo that enters cells majorly via the clathrin-independent pathway, it significantly attenuated the clathrin-dependent internalization of both epidermal growth factor and transferrin. Cell biological analyses revealed a marked increase in the size of early endosomes upon MC-22 treatment, indicating an endosomal trafficking/maturation defect. This study reports the identification of MC-22 as a novel CME-targeting, highly potent IAV entry inhibitor, which is expected to neutralize a broad spectrum of viruses that enter the host cells via CME.

Impact of influenza vaccination history in the clinical course of older adults hospitalized with COVID-19

BACKGROUND AND PURPOSE

Some studies have shown that influenza vaccination is associated with a lower risk of SARS-CoV-2 infection; in patients with COVID-19 infection, admission to intensive care is reduced, with less need for mechanical ventilation, shorter hospital stays, and reduced mortality. This study aimed to determine if a history of annual influenza vaccination impacts the clinical course of SARS-CoV-2 infection during hospitalization.

METHODS

This was an observational, prospective, cohort study of patients older than 65 admitted to the COVID-19 unit from January to June 2021. The history of influenza vaccination over the last 5 years was assessed in each patient during hospitalization. We measured the length of hospital stay, the need for admission to the intensive care unit (ICU), the patient's oxygen requirements, complications during hospitalization, and outcome (medical discharge or death). Patients with a history of vaccination against SARS-CoV-2 were not included.

RESULTS

We analyzed 125 patients, 50.4% (n=63) with history of influenza vaccination and 49.6% (n=62) without a history of influenza vaccination. In-hospital mortality was 44.8%, higher in the unvaccinated (54.8%) population (p=0.008). ICU admission was 27% higher in vaccinated (35%) patients (p=0.05). Patients without a history of influenza vaccination had a higher prevalence of cardiac (8% vs. 5%, p=0.04) and renal complications (29% vs. 13%, p=0.02). Patients with a history of vaccination had a greater need for invasive mechanical ventilation (25.4%, p=0.02).

CONCLUSION

In this study, a history of influenza vaccination in older adults with SARS-CoV-2 infection was related to lower in-hospital mortality.

The antigenic landscape of human influenza N2 neuraminidases from 2009 until 2017

Human H3N2 influenza viruses are subject to rapid antigenic evolution which translates into frequent updates of the composition of seasonal influenza vaccines. Despite these updates, the effectiveness of influenza vaccines against H3N2-associated disease is suboptimal. Seasonal influenza vaccines primarily induce hemagglutinin-specific antibody responses. However, antibodies directed against influenza neuraminidase (NA) also contribute to protection. Here, we analysed the antigenic diversity of a panel of N2 NAs derived from human H3N2 viruses that circulated between 2009 and 2017. The antigenic breadth of these NAs was determined based on the NA inhibition (NAI) of a broad panel of ferret and mouse immune sera that were raised by infection and recombinant N2 NA immunisation. This assessment allowed us to distinguish at least four antigenic groups in the N2 NAs derived from human H3N2 viruses that circulated between 2009 and 2017. Computational analysis further revealed that the amino acid residues in N2 NA that have a major impact on susceptibility to NAI by immune sera are in proximity of the catalytic site. Finally, a machine learning method was developed that allowed to accurately predict the impact of mutations that are present in our N2 NA panel on NAI. These findings have important implications for the renewed interest to develop improved influenza vaccines based on the inclusion of a protective NA antigen formulation.

Effectiveness of inactivated influenza vaccine against laboratory-confirmed influenza among Chinese elderly: a test-negative design

BACKGROUND

Evidence on the effectiveness of influenza vaccination in the elderly is limited, and results are controversial. There are also few reports from China.

METHODS

We conducted a test-negative case-control study design to estimate influenza vaccine effectiveness (VE) against laboratory-confirmed influenza-associated visits among elderly (aged ≥ 60 years) across four influenza seasons in Ningbo, China, from 2018 to 19 to 2021-22. Influenza-positive cases and negative controls were randomly matched in a 1:1 ratio according to age, sex, hospital, and date of influenza testing. We used logistic regression models to compare vaccination odds ratios (ORs) in cases to controls. We calculated the VE as [100% × (1-adjusted OR)] and calculated the 95% confidence interval (CI) around the estimate.

RESULTS

A total of 30,630 elderly patients tested for influenza with virus nucleic acid or antigen during the study period. After exclusions, we included 1 825 influenza-positive cases and 1 825 influenza-negative controls. Overall, the adjusted VE for influenza-related visits was 63.5% (95% CI, 56.3-69.5%), but varied by season. Influenza VE was 59.8% (95% CI, 51.5-66.7%) for influenza A and 89.6% (95% CI, 77.1-95.3%) for influenza B. The VE for ages 60-69 and 70-79 was 65.2% (95% CI, 55.4-72.9%) and 69.8% (95% CI, 58.7-77.9%), respectively, but only 45.4% (95% CI, 6.2-68.2%) for ages 80 and over.

CONCLUSIONS

Standard-dose inactivated influenza vaccine has shown good protection in the elderly in China. However, protection may not be satisfactory in people aged 80 years and older.

Antiviral influenza treatments and hemorrhage-related adverse events in the United States Food and Drug Administration Adverse Event Reporting System (FAERS) database

STUDY OBJECTIVE

To determine whether there is a signal for gastrointestinal (GI) or intracranial (IC) hemorrhage associated with the use of antiviral medications for influenza in the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database.

DESIGN

Disproportionality analysis.

DATA SOURCE

The FAERS database was searched using OpenVigil 2.1 to identify GI and IC hemorrhage events reported between 2004 and 2022.

MEASUREMENTS

Antiviral medications for influenza included the following: oseltamivir, zanamivir, peramivir, and baloxavir marboxil. Hemorrhage events were identified using Standardized Medical Dictionary for Regulatory Activities (MedDRA) Queries for GI and IC hemorrhages. Reporting odds ratios (RORs) were calculated to compare the occurrence of GI and IC hemorrhage events between antiviral drugs for influenza and (i) all other medications and (ii) antibiotics. RORs were also calculated for each of the individual antiviral medications.

MAIN RESULTS

A total of 245 cases of GI hemorrhage and 23 cases of IC hemorrhage were identified in association with four antivirals. In comparison with all other drugs, the RORs of GI hemorrhage for oseltamivir, zanamivir, peramivir, baloxavir, and all antivirals combined were 1.17, 0.62, 4.44, 2.53, and 1.22, respectively, indicating potential variations in GI hemorrhage risk among the antivirals. In contrast, in comparison with all other drugs, the RORs of IC hemorrhage for oseltamivir (0.44), zanamivir (0.16), baloxavir (0.44), and all antivirals combined (0.41) were less than 1.0 which is consistent with no elevated risk of IC hemorrhage.

CONCLUSION

In this study, some signals for GI hemorrhage were observed, particularly for peramivir and baloxavir marboxil. Further investigation is warranted to better understand and evaluate the potential risks of GI hemorrhage associated with antiviral treatments for influenza.

Respiratory Syncytial Virus and Influenza During the COVID-19 Pandemic: A Two-center Experience

BACKGROUND

The aim of the study was to determine the burden of respiratory syncytial virus (RSV) and influenza disease during the COVID-19 pandemic at 2 Austrian urban pediatric centers between October 1, 2019 and April 30, 2022.

METHODS

We performed a retrospective observational 2-center study on RSV- and influenza virus-associated hospitalizations in infants and children up to 18 years at the University Hospital of Graz and the Clinic Donaustadt of Vienna from October 1, 2019 to April 30, 2022. Hospitalization had to be associated with the infectious disease, proven by polymerase chain reaction, including presence of respiratory symptoms. Demographic data including underlying diseases and treatment strategies were compared between centers and diseases, respectively.

RESULTS

There were 826 cases in Graz and 379 in Vienna with significant more RSV cases in Graz and more influenza cases in Vienna (RSV: 76% vs. 59%, influenza: 24% vs. 41%; both P < 0.001). One death occurred in Graz due to RSV and another due to influenza in Vienna. Seasonality only slightly differed between centers and severity of diseases was not aggravated when measured by pediatric intensive care unit admission rates, need for supplemental oxygen and respiratory support between first and last seasons. Treatment regimen differed regarding higher use of antibiotics and rates of intravenous fluids in Vienna compared to higher rates of bronchodilators, corticosteroids and nose drops in Graz.

CONCLUSIONS

We observed higher numbers of hospitalizations due to both viruses after the lockdown but not increased severity of the diseases; and mortality remained extremely low. Preventive measures should be implemented with high priority especially focused on infants with underlying diseases.

Real-time investigation of an influenza A(H3N2) virus outbreak in a refugee community, November 2022

OBJECTIVES

To report epidemiological and virological results of an outbreak investigation of influenza-like illness (ILI) among refugees in Northern Italy.

STUDY DESIGN

Outbreak investigation of ILI cases observed among nearly 100 refugees in Northern Italy unvaccinated for influenza.

METHODS

An epidemiological investigation matched with a differential diagnosis was carried out for each sample collected from ILI cases to identify 10 viral pathogens (SARS-CoV-2, influenza virus type A and B, respiratory syncytial virus, metapneumovirus, parainfluenza viruses, rhinovirus, enterovirus, parechovirus, and adenovirus) by using specific real-time PCR assays according to the Centers for Disease Control and Prevention (CDC) protocols. In cases where the influenza virus type was identified, complete hemagglutinin (HA) gene sequencing and the related phylogenetic analysis were conducted.

RESULTS

The outbreak was caused by influenza A(H3N2): the attack rate was 83.3% in children aged 9-14 years, 84.6% in those aged 15-24 years, and 28.6% in adults ≥25 years. Phylogenetic analyses uncovered that A(H3N2) strains were closely related since they segregated in the same cluster, showing both a high mean nucleotide identity (100%), all belonging to the genetic sub-group 3C.2a1b.2a.2, as those mainly circulating into the general population in the same period.

CONCLUSIONS

The fact that influenza outbreak strains as well as the community strains were genetically related to the seasonal vaccine strain suggests that if an influenza prevention by vaccination strategy had been implemented, a lower attack rate of A(H3N2) and ILI cases might have been achieved.

Melatonin improves influenza virus infection-induced acute exacerbation of COPD by suppressing macrophage M1 polarization and apoptosis

BACKGROUND

Influenza A viruses (IAV) are extremely common respiratory viruses for the acute exacerbation of chronic obstructive pulmonary disease (AECOPD), in which IAV infection may further evoke abnormal macrophage polarization, amplify cytokine storms. Melatonin exerts potential effects of anti-inflammation and anti-IAV infection, while its effects on IAV infection-induced AECOPD are poorly understood.

METHODS

COPD mice models were established through cigarette smoke exposure for consecutive 24 weeks, evaluated by the detection of lung function. AECOPD mice models were established through the intratracheal atomization of influenza A/H3N2 stocks in COPD mice, and were injected intraperitoneally with melatonin (Mel). Then, The polarization of alveolar macrophages (AMs) was assayed by flow cytometry of bronchoalveolar lavage (BAL) cells. In vitro, the effects of melatonin on macrophage polarization were analyzed in IAV-infected Cigarette smoking extract (CSE)-stimulated Raw264.7 macrophages. Moreover, the roles of the melatonin receptors (MTs) in regulating macrophage polarization and apoptosis were determined using MTs antagonist luzindole.

RESULTS

The present results demonstrated that IAV/H3N2 infection deteriorated lung function (reduced FEV20,50/FVC), exacerbated lung damages in COPD mice with higher dual polarization of AMs. Melatonin therapy improved airflow limitation and lung damages of AECOPD mice by decreasing IAV nucleoprotein (IAV-NP) protein levels and the M1 polarization of pulmonary macrophages. Furthermore, in CSE-stimulated Raw264.7 cells, IAV infection further promoted the dual polarization of macrophages accompanied with decreased MT1 expression. Melatonin decreased STAT1 phosphorylation, the levels of M1 markers and IAV-NP via MTs reflected by the addition of luzindole. Recombinant IL-1β attenuated the inhibitory effects of melatonin on IAV infection and STAT1-driven M1 polarization, while its converting enzyme inhibitor VX765 potentiated the inhibitory effects of melatonin on them. Moreover, melatonin inhibited IAV infection-induced apoptosis by suppressing IL-1β/STAT1 signaling via MTs.

CONCLUSIONS

These findings suggested that melatonin inhibited IAV infection, improved lung function and lung damages of AECOPD via suppressing IL-1β/STAT1-driven macrophage M1 polarization and apoptosis in a MTs-dependent manner. Melatonin may be considered as a potential therapeutic agent for influenza virus infection-induced AECOPD.

Viral Pneumonia: From Influenza to COVID-19

Respiratory viruses are increasingly recognized as a cause of community-acquired pneumonia (CAP). The implementation of new diagnostic technologies has facilitated their identification, especially in vulnerable population such as immunocompromised and elderly patients and those with severe cases of pneumonia. In terms of severity and outcomes, viral pneumonia caused by influenza viruses appears similar to that caused by non-influenza viruses. Although several respiratory viruses may cause CAP, antiviral therapy is available only in cases of CAP caused by influenza virus or respiratory syncytial virus. Currently, evidence-based supportive care is key to managing severe viral pneumonia. We discuss the evidence surrounding epidemiology, diagnosis, management, treatment, and prevention of viral pneumonia.

Evidence for vagal sensory neural involvement in influenza pathogenesis and disease

Influenza A virus (IAV) is a common respiratory pathogen and a global cause of significant and often severe morbidity. Although inflammatory immune responses to IAV infections are well described, little is known about how neuroimmune processes contribute to IAV pathogenesis. In the present study, we employed surgical, genetic, and pharmacological approaches to manipulate pulmonary vagal sensory neuron innervation and activity in the lungs to explore potential crosstalk between pulmonary sensory neurons and immune processes. Intranasal inoculation of mice with H1N1 strains of IAV resulted in stereotypical antiviral lung inflammation and tissue pathology, changes in breathing, loss of body weight and other clinical signs of severe IAV disease. Unilateral cervical vagotomy and genetic ablation of pulmonary vagal sensory neurons had a moderate effect on the pulmonary inflammation induced by IAV infection, but significantly worsened clinical disease presentation. Inhibition of pulmonary vagal sensory neuron activity via inhalation of the charged sodium channel blocker, QX-314, resulted in a moderate decrease in lung pathology, but again this was accompanied by a paradoxical worsening of clinical signs. Notably, vagal sensory ganglia neuroinflammation was induced by IAV infection and this was significantly potentiated by QX-314 administration. This vagal ganglia hyperinflammation was characterized by alterations in IAV-induced host defense gene expression, increased neuropeptide gene and protein expression, and an increase in the number of inflammatory cells present within the ganglia. These data suggest that pulmonary vagal sensory neurons play a role in the regulation of the inflammatory process during IAV infection and suggest that vagal neuroinflammation may be an important contributor to IAV pathogenesis and clinical presentation. Targeting these pathways could offer therapeutic opportunities to treat IAV-induced morbidity and mortality.

Bloodstream Infections in Children Hospitalized for Influenza, the Canadian Immunization Monitoring Program Active

BACKGROUND

We aimed to estimate the proportion of children hospitalized for influenza whose illness was complicated by bloodstream infection, describe their clinical course, and identify the factors associated with bloodstream infection.

METHODS

We performed active surveillance for laboratory-confirmed influenza hospitalizations among children ≤16 years old at the 12 Canadian Immunization Monitoring Program Active hospitals, from the 2010-2011 to 2020-2021 influenza seasons. Factors associated with bloodstream infection were identified using multivariable logistic regression analyses.

RESULTS

Among 9179 laboratory-confirmed influenza hospital admissions, bloodstream infection occurred in 87 children (0.9%). Streptococcus pyogenes (22%), Staphylococcus aureus (18%) and Streptococcus pneumoniae (17%) were the most common bloodstream infection pathogens identified. Children with cancer [adjusted odds ratio (aOR): 2.78; 95% confidence interval (CI): 1.23-5.63], a laboratory-confirmed nonbloodstream bacterial infection (aOR: 14.1; 95% CI: 8.04-24.3) or radiographically-confirmed pneumonia (aOR: 1.87; 95% CI: 1.17-2.97) were more likely to experience a bloodstream infection, whereas children with chronic lung disorders were less likely (aOR: 0.41; 95% CI: 0.19-0.80). Disease severity markers such as intensive care unit admission (aOR: 2.11; 95% CI: 1.27-3.46), mechanical ventilation (aOR: 2.84; 95% CI: 1.63-4.80) and longer hospital length of stay (aOR: 1.02; 95% CI: 1.01-1.03) were associated with bloodstream infection. Bloodstream infection also increased the odds of death (aOR: 13.0; 95% CI: 4.84-29.1) after adjustment for age, influenza virus type and the presence of any at-risk chronic condition.

CONCLUSIONS

Bloodstream infections, although infrequent, are associated with intensive care unit admission, mechanical ventilation, increased hospital length of stay and in-hospital mortality, thus requiring increased levels of care among pediatric influenza hospitalizations.

Clinical profile of children with influenza like illness during pre-monsoon at coastal Karaikal, Puducherry, India

Influenza infections in developing countries are under reported and WHO estimates that nearly 99% of influenza deaths worldwide occur in children under-five years of age in Asian and African countries. Consequently, this study aims to analyze the use of clinical profile and easily available laboratory parameters to aid identification of the possible viral etiology in the setting of pre-monsoon ILI. A cross-sectional study was carried out for three months among children with ILI attending fever clinic of a tertiary care hospital in Karaikal, South India. In the study population the prevalence of ILI was highest in the age group four to five years followed by school aged children. Adolescents were affected the least. Influenza B was most common virus causing ILI in this region, followed by covid-19 infection. Laboratory parameters depicted a significantly high ESR in COVID-19 infected ILI children. They also exhibited leucopenia and normal platelet counts. Clinical symptoms and laboratory parameters which are easily available and cheaper can be used in resource poor settings of healthcare to identify possible influenza and COVID-19 infected children amongst cases presenting with ILI.

The economic and fiscal impact of incremental use of cell-based quadrivalent influenza vaccine for the prevention of seasonal influenza among healthcare workers in Italy

BACKGROUND

Seasonal influenza has a significant impact on public health, generating substantial direct healthcare costs, production losses and fiscal effects. Understanding these consequences is crucial to effective decision-making and the development of preventive strategies. This study aimed to evaluate the economic and the fiscal impact of implementing an incremental strategy for seasonal influenza prevention using the cell-based quadrivalent influenza vaccine (QIVc) among healthcare workers (HCWs) in Italy.

METHODS

To estimate the economic impact of implementing this strategy, we performed a cost analysis that considered direct healthcare costs, productivity losses and fiscal impact. The analysis considered a 3-year time horizon. A deterministic sensitivity analysis was also conducted.

RESULTS

Assuming a vaccination coverage rate of 30% among HCWs, the analysis considered a total of 203 018 vaccinated subjects. On analysing the overall differential impact (including direct costs, indirect costs and fiscal impact), implementing QIVc vaccination as a preventative measure against influenza among HCWs in Italy would yield societal resource savings of €23 638.78 in the first year, €47 277.56 in the second year, and €70 916.35 in the third year, resulting in total resource savings of €141 832.69.

CONCLUSIONS

The study demonstrated that implementing the incremental use of QIVc as part of a preventive strategy for seasonal influenza among HCWs in Italy could yield positive economic outcomes, especially in terms of indirect costs and fiscal impact. The resources saved could be utilized to fund further public health interventions. Policy-makers should consider these findings when making decisions regarding influenza prevention strategies targeting HCWs.

Real-world effectiveness of seasonal influenza vaccination and age as effect modifier: A systematic review, meta-analysis and meta-regression of test-negative design studies

BACKGROUND

Under the global risk of epidemic rebound of influenza after COVID-19 outbreak, the study aimed to provide a comprehensive evaluation of the seasonal influenza vaccine effectiveness (IVE) and to explore the potential effect modifiers.

METHODS

We searched for test-negative design studies with IVE estimates published between January 1, 2017 and December 31, 2022. We estimated pooled IVE using random-effects meta-analysis, and conducted meta-regression with study site, age, sex and comorbidity as explanatory variables.

RESULTS

We identified 2429 publications and included 191 in the meta-analysis. The pooled IVE was 41.4 % (95 % CI: 39.2-43.5 %) against any influenza. For specific strains, the IVE was 55.4 % (95 % CI: 52.7-58.1 %) against A/H1N1, 26.8 % (95 % CI: 23.5-29.9 %) against A/H3N2, 47.2 % (95 % CI: 38.1-54.9 %) against B/Yamagata, and 40.6 % (95 % CI: 23.7-53.7 %) against B/Victoria, and the effectiveness against A/H3N2 was significantly lower than A/H1N1 (p < 0.0001) and B/Yamagata (p < 0.0001). The pooled IVE was 39.2 % (95 % CI: 36.5-41.9 %) in preventing influenza-associated outpatient visit and 43.7 % (95 % CI: 39.7-47.4 %) in preventing influenza-related hospitalization. The IVE against any influenza was 48.6 % (95 % CI: 44.7-52.2 %) for children aged < 18 years, 36.7 % (95 % CI: 31.9-41.1 %) for adults aged 18-64 years, and 30.6 % (95 % CI: 26.2-34.8 %) for elderly aged ≥65 years. Meta-regression revealed that the IVE was associated with the average age of study participants, in which both young adults [relative odds ratio (ROR) = 1.225, 95 % confidence interval (CI): 1.099-1.365, p = 0.0002] and elderly (ROR = 1.245, 95 % CI: 1.083-1.431, p = 0.002) manifested a significantly decreased effectiveness compared with children.

CONCLUSIONS

Influenza vaccines provided moderate protection against laboratory-confirmed influenza and related outpatient visit and hospitalization. However, the effectiveness may vary substantially by virus type and age group, suggesting the necessity to tailor vaccination strategies especially for older individuals and against the A/H3N2 strain, and to promote annual immunization and annual analysis of vaccine effectiveness.

Analysis of clinical characteristics and risk factors for death due to severe influenza in children

OBJECTIVE

The study analyzed the clinical features of children who had severe influenza and discussed on the risk factors associated with death in this population.

METHODS

A total of 167 children with severe influenza admitted to the intensive care unit of our hospital from January 2018 to August 2023 were selected and divided into the death group (27 cases) and the survival group (140 cases). Demographic characteristics and clinical data were collected and compared between the two groups. Logistic regression analysis was used to explore the risk factors for death in children with severe influenza.

RESULTS

The male-to-female ratio of the 167 children with severe influenza was 2.21:1, the median age was 3 years, and influenza A accounted for 70.66%. The CD4+ T cells percentage and CD4/CD8 were lower in the death group; the percentage of comorbid underlying diseases, mechanical ventilation, other systemic involvement, comorbid associated encephalopathy or encephalitis, and red blood cell distribution width (RDW), lactate dehydrogenase, activated partial thromboplastin time (APTT), and interleukin 6 were higher in the death group. The mechanical ventilation, associated encephalopathy or encephalitis, RDW, APTT, and CD4/CD8 were the independent risk factors for death.

CONCLUSION

Mechanical ventilation, comorbid encephalopathy or encephalitis, increased RDW, prolonged APTT, and decreased CD4/CD8 are independent risk factors for death in children with severe influenza.

SARS-CoV-2 and influenza virus coinfections in the Tuscan population during the 2021/2022 influenza season

Introduction

The 2021/2022 influenza season was not characterised by a well-defined incidence peak. As reported by the Italian National Institute of Health, a high value of incidence of influenza cases was recorded in week 13, but it was still lower than in other influenza seasons. This abnormal circulation was probably due to relaxation of the COVID-19 pandemic restriction measures, such as social distancing, smart-working, home leaning and the use of masks, which greatly reduced the circulation of respiratory-transmitted viruses, including human respiratory syncytial virus (HRSV). The symptoms of SARS-CoV-2 and influenza are quite similar, sharing the human-to-human transmission route via respiratory droplets.

Methods

The aim of this study was to estimate the rate of coinfection with influenza viruses and/or HRSV in SARS-CoV-2-positive subjects (N = 940) in a population of central Italy during the 2021/2022 season.

Results

A total of 54 cases of coinfection were detected during the study period, 51 cases (5.4%) of SARS-CoV-2 and influenza virus and three cases (0.3%) of SARS-CoV-2 and HRSV coinfection.

Conclusions

These results highlight the importance of continuous monitoring of the circulation of influenza virus and other respiratory viruses in the context of the COVID-19 pandemic.

Discovery of a Macrocyclic Influenza Cap-Dependent Endonuclease Inhibitor

Influenza viruses (IFVs) have caused several pandemics and have claimed numerous lives since their first record in the early 20th century. While the outbreak of COVID-19 seemed to expel influenza from the sight of people for a short period of time, it is not surprising that it will recirculate around the globe after the coronavirus has mutated into a less fatal variant. Baloxavir marboxil (1), the prodrug of baloxavir (2) and a cap-dependent endonuclease (CEN) inhibitor, were approved by the FDA for the first treatment in almost 20 years. Despite their high antiviral potency, drug-resistant variants have been observed in clinical trials. Herein, we report a novel CEN inhibitor 8 with a delicately designed macrocyclic scaffold that exhibits a significantly smaller shift of inhibitory activity toward baloxavir-resistant variants.

Healthcare-seeking behaviours of patients with acute respiratory infection: a cross-sectional survey in a rural area of southwest China

OBJECTIVES

This study aimed to assess the healthcare-seeking behaviour and related factors of people with acute respiratory symptoms in the rural areas of central and western China to estimate the disease burden of influenza more accurately.

DESIGN

Cross-sectional survey.

SETTINGS

Fifty-two communities/villages in the Wanzhou District, Chongqing, China, a rural area in southwest China, from May 2022 to July 2022.

PARTICIPANTS

The participants were those who had been living in Wanzhou District continuously for more than 6 months and consented to participate.

OUTCOME MEASURES

A semistructured questionnaire was used to determine the healthcare-seeking behaviour of participants, and the dichotomous response of 'yes' or 'no' was used to assess whether participants had acute respiratory symptoms and their healthcare-seeking behaviour.

RESULTS

Only 50.92% (360 of 707) of the patients with acute respiratory infection visited medical and health institutions for treatment, whereas 49.08% (347 of 707) avoided treatment or opted for self-medication. The primary reason for not seeing a doctor was that patients felt their condition was not serious and visiting a medical facility for treatment was unnecessary. Short distance (87.54%) and reasonable charges (49.48%) were ranked as the most important reasons for choosing treatment at primary medical and health facilities (80.27%). The primary reasons for which patients visited secondary and tertiary hospitals (7.78% and 8.61%, respectively) were that doctors in such facilities were better at diagnosis (57.14%) and at treatment (87.10%).

CONCLUSION

The findings provided in this study indicated that regular healthcare-seeking behaviour investigations should be conducted. The disease burden of influenza can be calculated more accurately when healthcare-seeking behaviour investigations are combined with surveillance in the hospitals.

Factors associated to the presence of headache in patients with influenza infection and its consequences: a 2010-2020 surveillance-based study

Headache is a common symptom of influenza infection; however, its causes and consequences remain uncertain. In this manuscript, we analyzed which demographic and clinical factors were associated with the presence of headache during the course of influenza infection and whether patients with headache had a different prognosis, evaluated by need of hospitalization, sick leave or school absenteeism. The influence study (NCT05704335) was an observational study that analyzed data routinely collected from the Health Sentinel Network between 2010 and 2020. During the study period, 7832 cases were considered, among which, 5275 (67.4%) reported headache. The presence of headache was independently associated with myalgia (2.753; 95%CI: 2.456-3.087, P < 0.001), asthenia (OR: 1.958; 95%CI: 1.732-2.214, P < 0.001), shivering (OR: 1.925; 95%CI: 1.718-2.156, P < 0.001), nasopharyngeal erythema (OR: 1.505; 95%CI: 1.293-1.753, P < 0.001), fever (OR: 1.469; 95%CI: 1.159-1.861; P = 0.001), sudden onset of symptoms (OR: 1.380; 95%CI: 1.120-1.702, p = 0.004), female sex (OR: 1.134; 95%CI: 1.023-1.257, P = 0.018), and gastrointestinal symptoms (OR: 1.169; 95%CI: 1.039-1.315; P = 0.01). Patients with headache had a sex and age adjusted lower odds of being referred to the hospital (OR: 0.463; 95%CI: 0.264-0.812, P = 0.007) and a higher odd of having a sick leave and/or school absenteeism (absenteeism (OR: 1.342; 95%CI: 1.190-1.514, P < 0.001). In conclusion, the presence of headache seems associated with symptoms caused by the innate immune response. These findings support a headache pathophysiology linked with the innate immune response. Due to the potential negative consequences and its treatable nature, clinicians should systematically evaluate it and, whenever necessary, treat it too.

Leveraging baseline transcriptional features and information from single-cell data to power the prediction of influenza vaccine response

Introduction

Vaccination is still the primary means for preventing influenza virus infection, but the protective effects vary greatly among individuals. Identifying individuals at risk of low response to influenza vaccination is important. This study aimed to explore improved strategies for constructing predictive models of influenza vaccine response using gene expression data.

Methods

We first used gene expression and immune response data from the Immune Signatures Data Resource (IS2) to define influenza vaccine response-related transcriptional expression and alteration features at different time points across vaccination via differential expression analysis. Then, we mapped these features to single-cell resolution using additional published single-cell data to investigate the possible mechanism. Finally, we explored the potential of these identified transcriptional features in predicting influenza vaccine response. We used several modeling strategies and also attempted to leverage the information from single-cell RNA sequencing (scRNA-seq) data to optimize the predictive models.

Results

The results showed that models based on genes showing differential expression (DEGs) or fold change (DFGs) at day 7 post-vaccination performed the best in internal validation, while models based on DFGs had a better performance in external validation than those based on DEGs. In addition, incorporating baseline predictors could improve the performance of models based on days 1-3, while the model based on the expression profile of plasma cells deconvoluted from the model that used DEGs at day 7 as predictors showed an improved performance in external validation.

Conclusion

Our study emphasizes the value of using combination modeling strategy and leveraging information from single-cell levels in constructing influenza vaccine response predictive models.

Community-acquired and hospital-acquired bacterial co-infections in patients hospitalized with Covid-19 or influenza: a retrospective cohort study

BACKGROUND

Bacterial co-infections are believed to be less frequent in patients with Covid-19 than influenza, but frequencies varied between studies.

METHODS

This single-center retrospective, propensity score-matched analysis included adult patients with Covid-19 or influenza admitted to normal-care wards between 02/2014 and 12/2021. Covid-19 cases were propensity score matched to influenza cases at a 2:1 ratio. Community-acquired and hospital-acquired bacterial co-infections were defined as positive blood or respiratory cultures ≤ 48 h or > 48 h after hospital admission, respectively. The primary outcome was comparison of community-acquired and hospital-acquired bacterial infections between patients with Covid-19 and influenza in the propensity score-matched cohort. Secondary outcomes included frequency of early and late microbiological testing.

RESULTS

A total of 1337 patients were included in the overall analysis, of which 360 patients with Covid-19 were matched to 180 patients with influenza. Early (≤ 48 h) microbiological sampling was performed in 138 (38.3%) patients with Covid-19 and 75 (41.7%) patients with influenza. Community-acquired bacterial co-infections were found in 14 (3.9%) of 360 patients with Covid-19 and 7 (3.9%) of 180 patients with influenza (OR 1.0, 95% CI 0.3-2.7). Late (> 48 h) microbiological sampling was performed in 129 (35.8%) patients with Covid-19 and 74 (41.1%) patients with influenza. Hospital-acquired bacterial co-infections were found in 40 (11.1%) of 360 patients with Covid-19 and 20 (11.1%) of 180 patients with influenza (OR 1.0, 95% CI 0.5-1.8).

CONCLUSION

The rate of community-acquired and hospital-acquired bacterial co-infections was similar in hospitalized Covid-19 and influenza patients. These findings contrast previous literature reporting that bacterial co-infections are less common in Covid-19 than influenza.

Promises and challenges of single-domain antibodies to control influenza

The World Health Organization advices the use of a quadrivalent vaccine as prophylaxis against influenza, to prevent severe influenza-associated disease and -mortality, and to keep up with influenza antigenic diversity. Different small molecule antivirals to treat influenza have become available. However, emergence of drug resistant influenza viruses has been observed upon use of these antivirals. An appealing alternative approach to prevent or treat influenza is the use of antibody-based antivirals, such as conventional monoclonal antibodies and single-domain antibodies (sdAbs). The surface of the influenza A and B virion is decorated with hemagglutinin molecules, which act as receptor-binding and membrane fusion proteins and represent the main target of neutralizing antibodies. SdAbs that target influenza A and B hemagglutinin have been described. In addition, sdAbs directed against the influenza A virus neuraminidase have been reported, whereas no sdAbs targeting influenza B neuraminidase have been described to date. SdAbs directed against influenza A matrix protein 2 or its ectodomain have been reported, while no sdAbs have been described targeting the influenza B matrix protein 2. Known for their high specificity, ease of production and formatting, sdAb-based antivirals could be a major leap forward in influenza control.

Changes in Epidemiology and Antibiotic Prescription of Influenza: Before and after the Emergence of COVID-19

BACKGROUND

The appearance of COVID-19 had a major impact on healthcare and the epidemiology of other diseases. Following the cessation of non-pharmacologic interventions destined to limit the spread of COVID-19, influenza reemerged. The aim of this study was to compare the pre-pandemic influenza seasons with the influenza seasons after the emergence of the COVID-19 pandemic, and to identify differences in terms of clinical characteristics, risk factors, complications, outcomes, and antiviral and antibiotic treatments.

METHODS

We conducted a retrospective cohort study from the Teaching Hospital of Infectious Diseases database in Cluj-Napoca, Romania. We analyzed four pre-pandemic seasons and the seasons after the onset of COVID-19. We included adult patients hospitalized with confirmed influenza between October 2016 and August 2023. Variables such as age, sex, duration of hospitalization, severity, clinical manifestations, comorbidities, and Charlson comorbidity index were assessed.

RESULTS

A total of 941 patients were included in the analysis. The percentage of severe influenza was similar in both groups, but mortality from influenza was significantly lower after 2022. Virtually all patients were prescribed antivirals; antibiotic prescriptions decreased in the post-COVID-19 influenza seasons.

CONCLUSION

The present study suggests that influenza seasons after 2022 had lower mortality and attenuated clinical presentation.

Heteromultivalent Ligand Display on Reversible Self-Assembled Monolayers (rSAMs): A Fluidic Platform for Tunable Influenza Virus Recognition

We report on the design of heteromultivalent influenza A virus (IAV) receptors based on reversible self-assembled monolayers (SAMs) featuring two distinct mobile ligands. The principal layer building blocks consist of α-(4-amidinophenoxy)alkanes decorated at the ω-position with sialic acid (SA) and the neuraminidase inhibitor Zanamivir (Zan), acting as two mobile ligands binding to the complementary receptors hemagglutinin (HA) and neuraminidase (NA) on the virus surface. From ternary amphiphile mixtures comprising these ligands, the amidines spontaneously self-assemble on top of carboxylic acid-terminated SAMs to form reversible mixed monolayers (rSAMs) that are easily tunable with respect to the ligand ratio. We show that this results in the ability to construct surfaces featuring a very strong affinity for the surface proteins and specific virus subtypes. Hence, an rSAM prepared from solutions containing 15% SA and 10% Zan showed an exceptionally high affinity and selectivity for the avian IAV H7N9 (Kd = 11 fM) that strongly exceeded the affinity for other subtypes (H3N2, H5N1, H1N1). Changing the SA/Zan ratio resulted in changes in the relative preference between the four tested subtypes, suggesting this to be a key parameter for rapid adjustments of both virus affinity and selectivity.

Influenza vaccine compatibility among hospitalized patients during and after the COVID-19 pandemic

Introduction

Following the significant decrease in SARS-CoV-2 cases worldwide, Israel, as well as other countries, have again been faced with a rise in seasonal influenza. This study compared circulating influenza A and B in hospitalized patients in Israel with the influenza strains in the vaccine following the 2021-2022 winter season which was dominated by the omicron variant.

Methods

Nasopharyngeal samples of 16,325 patients were examined for the detection of influenza A(H1N1)pdm09, influenza A(H1N1)pdm09 and influenza B. Phylogenetic trees of hemagglutinin were then prepared using sanger sequencing. Vaccine immunogenicity was also performed using the hemagglutination inhibition test.

Results

Of the 16,325 nasopharyngeal samples collected from hospitalized patients between September 2021 (Week 40) and April 2023 (Week 15), 7.5% were found to be positive for influenza. Phylogenetic analyses show that in the 2021-2022 winter season, the leading virus subtype was influenza A(H3N2), belonging to clade 3C.2a1b.2a.2. However, the following winter season was dominated by influenza A(H1N1)pdm09, which belongs to clade 6B.aA.5a.2. The circulating influenza A(H1N1)pdm09 strain showed a shift from the vaccine strain, while the co-circulating influenza A(H3N2) and influenza B strains were similar to those of the vaccine. Antigenic analysis coincided with the sequence analysis.

Discussion

Influenza prevalence during 2022-2023 returned to typical levels as seen prior to the emergence of SARS-CoV-2, which may suggest a gradual viral adaptation to SARS-CoV-2 variants. Domination of influenza A(H1N1)pdm09 was observed uniquely in Israel compared to Europe and USA and phylogenetic and antigenic analysis showed lower recognition of the vaccine with the circulating influenza A(H1N1)pdm09 in Israel compared to the vaccine.

A Universal Aptamer for Influenza A Viruses: Selection, Recognition, and Infection Inhibition

It is crucial to develop universal inhibitors for viral inhibition due to the rapid mutation of viruses. Herein, a universal aptamer inhibitor was developed that enabled a single DNA molecule to recognize several hemeagglutinin (HA) protein subtypes, inducing broad neutralization against influenza A viruses (IAVs). Through a multi-channel enrichment (MCE) strategy, a high-affinity aptamer named UHA-2 was obtained, with its dissociation constants (Kd) for three different HA proteins being 1.5 ± 0.2 nM (H5N1), 3.7 ± 0.4 nM (H7N9), and 10.1 ± 1.1 nM (H9N2). The UHA-2 aptamer had a universal inhibition effect, by which it could broadly neutralize influenza A H5N1, H7N9, H9N2, H1N1, and H3N2 viruses. Universal aptamer inhibitors have the advantages of acquisition in vitro, stability, simple structure, small size, etc. This study not only develops a novel universal aptamer to achieve a broad inhibition effect on various IAVs, but also opens up an efficient strategy for the development of universal inhibitors against viruses.

Resurgence of influenza A after SARS-CoV-2 omicron wave and comparative analysis of hospitalized children with COVID-19 and influenza A virus infection

Context

The highly infectious Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have caused large-scale transmission from Dec 2022 to Feb 2023 in China. After this event, a remarkable surge of influenza A (Flu A) occurred from March to May 2023, especially in pediatric patients.

Objectives

This study aimed to investigate the differences between pediatric patients infected with COVID-19 Omicron and Flu A virus.

Methods

A total of 1,063 hospitalized children who admitted into two tertiary general hospital of Guangdong province of China were included. Medical records were compared retrospectively in these patients during the pandemic periods of SARS-CoV-2 omicron and Flu A.

Results

A total of 592 Patients with Flu A were mostly preschool and school-aged (>3y, 76.0%), they showed higher ratio of high fever (≥39°C), cough, rhinorrhea, and vomiting than patients with SARS-CoV-2 omicron. Most of the 471 Omicron patients were young children (0-3y, 74.5%) and had more poor appetite and dyspnea symptom. Benign acute children myositis (BACM) was only observed in patients with Flu A, and a significant male predominance. Multisystem inflammatory syndrome in children (MIS-C) was only found in patients with SARS-CoV-2 Omicron. Compared to the SARS-CoV-2 Omicron group, for both age groups (0-3 years and > 3 years), the Flu A group showed significantly reduced lymphocyte (Lym) counts (P < 0.001), and elevated levels of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatinine kinase-MB (CK-MB) in laboratory indexes (all P < 0.001). Additionally, it was found that more children hospitalized with COVID-19 had increased C-reactive protein (CRP) levels compared to those with Flu A.

Conclusion

Influenza A infections have notably surged in children, coinciding with the relaxation of COVID-19 related social restrictions. During the epidemic periods of Omicron and Flu A virus infection, different clinical and laboratory characteristics were observed in hospitalized children.

Risk factors for hospitalization and pneumonia development of pediatric patients with seasonal influenza during February-April 2023

Objectives

In China influenza remains a low activity for continuous 3 years due to COVID-19 controls. We here sought to study the clinical characteristics and risk factors of the influenza infection among children after the mandatory COVID-19 restrictions were lifted.

Methods

We included 1,006 pediatric patients with influenza A virus (IAV) infection, enrolled in one tertiary hospital in Zhenjiang, Jiangsu Province, China, during February to April 2023. Patients were divided into the outpatient (n = 798) and inpatient (n = 208) groups, and their baseline characteristics were compared between two groups to conclude the risk factors for pediatric hospitalization. Separately, pediatric inpatients (n = 208) were further divided into the pneumonia and non-pneumonia groups with comparison of their clinical characteristics, including their laboratory test results and representative radiological features, to derive the key determinants for pneumonia development after hospitalization.

Results

Compared to outpatients, IAV-infected pediatric inpatients exhibited younger age, higher female: male ratio, more co-infection of influenza B virus (IBV) and hematological abnormality. Multivariate regression analysis determined the independent risk factors of hospitalization to be the clinical symptom of abdominal pain (OR = 2.63, [95% CI, 1.05-6.57], p = 0.039), co-infection of IBV (OR = 44.33, [95% CI, 25.10-78.30], p = 0.001), elevated levels of lymphocytes (OR = 2.24, [95% CI,1.65-3.05], p = 0.001) and c-reactive proteins (CRPs) (OR = 1.06, [95% CI, 1.03-1.08], p = 0.001) upon hospital admission. Furthermore, the cough symptom (OR = 17.39, [95% CI, 3.51-86.13], p = 0.001) and hospitalization length (OR = 1.36, [95% CI, 1.12-1.67], p = 0.002) were determined to be risk factors of pneumonia acquirement for pediatric inpatients.

Conclusion

While the abdominal pain, viral co-infection and some hematological abnormality mainly contribute to hospitalization of pediatric patients with IAV infection, the length of hospital stay and clinical sign of coughing upon hospital admission constitute the key determinants for nosocomial pneumonia development.

Platelet distribution width as an useful indicator of influenza severity in children

PURPOSE

The present study aims to investigate the potential of platelet distribution width as an useful parameter to assess the severity of influenza in children.

METHODS

Baseline characteristics and laboratory results were collected and analyzed. Receiver operating characteristic (ROC) curve analysis was used to joint detection of inflammatory markers for influenza positive children, and the scatter-dot plots were used to compare the differences between severe and non-severe group.

RESULTS

Influenza B positive children had more bronchitis and pneumonia (P < 0.05), influenza A infected children had more other serious symptoms (P = 0.007). Neutrophil count, lymphocyte count, neutrophil-to-lymphocyte ratio (NLR), and platelet parameters performed differently among < 4 years and ≥ 4 years children with influenza. Combined detection of platelet parameters and other indicators could better separate healthy children from influenza infected children than single indicator detection. The levels of platelet distribution width of children with severe influenza (A and B) infection was significantly dropped, compared with non-severe group (P < 0.05).

CONCLUSIONS

Platelet distribution width could be a very useful and economic indicator in distinction and severity assessment for children with influenza.

Influvac Tetra: clinical experience on safety, efficacy, and immunogenicity

INTRODUCTION

This paper summarizes the safety and immunogenicity data of Influvac Tetra across all age groups starting from 6 months of age, obtained during its clinical development program.

AREAS COVERED

The article covers the clinical development program of Influvac Tetra based on five registration studies that included different age groups, different comparators, and participants from Europe and Asia. Safety and immunogenicity were assessed in all studies and in one study, the efficacy of Influvac Tetra was assessed.

EXPERT OPINION

Seasonal influenza is a vaccine-preventable disease that can cause serious complications. Several types of influenza vaccines are available, including egg-based (standard dose, high dose, and adjuvanted), cell-based, and recombinant. The COVID-19 pandemic has stimulated innovation in the development such as mRNA vaccines. However, these vaccines are still in development and the true value still has to be proven. Regardless of the type of vaccine, it is also important to increase overall vaccination coverage. ECDC recommends that EU Member States implement action plans and policies aimed at reaching 75% coverage in at-risk groups and healthcare workers. Even so, vaccine coverage is still far from recommended.

A systematic review of influenza virus in water environments across human, poultry, and wild bird habitats

Influenza, a highly contagious acute respiratory disease, remains a major global health concern. This study aimed to comprehensively assess the prevalence of influenza virus in different aquatic environments. Using 43 articles from four databases, we thoroughly examined water matrices from wastewater treatment plants (WTPs) and other human environments, as well as poultry habitats and areas frequented by migratory wild birds. In WTP influents (10 studies), positivity rates for influenza A ranged from 0.0 % to 97.6 %. For influenza B (8 studies), most studies reported no positivity, except for three studies reporting detection in 0.8 %, 5.6 %, and 46.9 % of samples. Within poultry habitats (13 studies), the prevalence of influenza A ranged from 4.3 % to 76.4 %, while in environments frequented by migratory wild birds (11 studies), it ranged from 0.4 % to 69.8 %. Geographically, the studies were distributed as follows: 39.5 % from the Americas, 18.6 % from Europe, 2.3 % from South-East Asia and 39.5 % from the Western Pacific. Several influenza A subtypes were found in water matrices, including avian influenza (H3N6, H3N8, H4N1, H4N2, H4N6, H4N8, H5N1, H5N8, H6N2, H6N6, H7N9, H0N8, and H11N9) and seasonal human influenza (H1N1 and H3N2). The existing literature indicates a crucial requirement for more extensive future research on this topic. Specifically, it emphasizes the need for method harmonization and delves into areas deserving of in-depth research, such as water matrices pertaining to pig farming and prevalence studies in low-income countries.

Inactivation of Three Subtypes of Influenza A Virus by a Commercial Device Using Ultraviolet Light and Ozone

Avian influenza (AI) is a highly contagious disease that can be transmitted to naïve birds through fomites. The survival of AI viruses (AIV) on nonporous and porous fomites also dictates how long the fomite can serve as a vehicle for virus transmission. AIVs are known to be inactivated by ozone and ultraviolet (UV) light. However, the combined effect of UV light and ozone in combating AIV on different fomites has not been investigated. This study was undertaken to determine AIV inactivation by a commercial device called the BioSec shoe sanitizing station. This device generates both ozone and UV light for 8 sec when activated. We evaluated this device against three different subtypes of AIVs applied on seven different fomites. In general, the device inactivated all three AIV subtypes loaded on all fomites but to varying degrees of inactivation. The percentage of virus reduction on nonporous fomites (98.6%-99.9%) was higher than on porous fomites (90.0%-99.5%). In conclusion, this new device has the potential to help reduce the risk of transmission of AIV.

The mortality and years of life lost for community-acquired pneumonia before and during COVID-19 pandemic in China

Background

Community-acquired pneumonia (CAP) is a leading cause of mortality worldwide, but disease burden of CAP is not clear so far. We aim to explore the spatial and temporal trends of mortality and years of life lost (YLL) due to CAP during 2013-2021 in mainland China, especially the mortality changes before and during COVID-19 pandemic due to COVID-19 related non-pharmaceutical interventions (NPIs).

Methods

We used data from the National Mortality Surveillance System to estimate the age-standardized rates of death and YLL of CAP at national and provincial level in China during 2013-2021. Monthly and provincial NPIs data were obtained from Oxford COVID-19 Government Response Tracker. The Average annual percentage change (AAPC) and mortality reduction were estimated by log-linear regression and interrupted time series, respectively.

Findings

In China, most CAP that caused deaths had no clear etiology, and bacterial pneumonia and viral pneumonia were the leading 2 causes among CAP deaths with determined etiology before and during COVID-19 pandemic. The age-standardized CAP mortality rate decreased from 11.18 per 100,000 in 2013 to 8.76 per 100,000 in 2019, and to 5.74 per 100,000 in 2021 (AAPC -4.51% vs -7.89%). Trends were similar in age-standardized rate of YLL. Both rates declined more for viral pneumonia, compared with bacterial pneumonia. After adjusting for NPIs at provincial level after 2020, the NPIs for COVID-19 was associated with significant reductions in CAP mortality (-0.34 per 100,000, -0.41 to -0.27; p < 0.0001), and provinces that economically developed and conducted strict regular NPIs against COVID-19 contributed the most reduction.

Interpretation

We observed a decreasing trend of age-standardized CAP mortality from 2013 to 2019, and a dramatical reduction during COVID-19 pandemic, especially for viral pneumonia. Our study provided the evidence for the effectiveness of regular NPIs on the significant reductions in CAP mortality.

Funding

This work has been supported by Beijing Municipal Science and Technology Project Z191100006619101, Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Sciences (CIFMS 2021-I2M-1-048), CAMS Institute of Respiratory Medicine Grant for Young Scholars (2023-ZF-8) and the New Cornerstone Science Foundation.

Evaluation of the efficacy, safety and influencing factors of concomitant and sequential administration of viral respiratory infectious disease vaccines: a systematic review and meta-analysis

Background

There is no clear conclusion on the immunogenicity and adverse events of concomitant administration the viral respiratory infectious disease vaccines. We aimed to evaluate the impact of concomitant administering viral respiratory infectious disease vaccines on efficiencies, safety and influencing factors.

Methods

This meta-analysis included studies from PubMed, Embase, Cochrane Central Register of Clinical Trials, Web of Science, WHO COVID-19 Research, and ClinicalTrials.gov databases. Randomized controlled trials of the adult participants concomitant administered with viral respiratory infectious disease vaccine and other vaccines were included. The main outcomes were the seroconversion rate and seroprotection rate of each vaccine. Used the Mantel-Haenszel fixed effects method as the main analysis to estimate the pooled RRs and the corresponding 95% confidence intervals. The risk of bias for each trial was assessed using the Cochrane Handbook for Systematic Reviews of Interventions, while evidence certainty was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation system.

Results

A total of 21 studies comprising 14060 participants with two types of vaccines were retained for the meta-analysis. Concomitant immunization reduced the geometric mean titer (RR: 0.858, 95% CI: (0.785 to 0.939)) and the geometric mean fold rise (0.754 (0.629 to 0.902)) in the SARS-COV-2 vaccine group but increased the seroconversion rate (1.033 (1.0002 to 1.067)) in the seasonal influenza vaccine group. Concomitant administration were influenced by the type of vaccine, adjuvant content, booster immunization, and age and gender of the recipient.

Conclusion

This meta-analysis suggested that the short-term protection and safety of concomitant administered were effective. Appropriate adjuvants, health promotion and counselling and booster vaccines could improve the efficiency and safety of Concomitant vaccination.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022343709.

Active surveillance for influenza virus and coronavirus infection in Antarctic birds and mammals in environmental fecal samples, South Shetland Islands

Numerous Antarctic species are recognized as reservoirs for various pathogens, and their migratory behavior allows them to reach the Brazilian coast, potentially contributing to the emergence and circulation of new infectious diseases. To address the potential zoonotic risks, we conducted surveillance of influenza A virus (IAV) and coronaviruses (CoVs) in the Antarctic Peninsula, specifically focusing on different bird and mammal species in the region. During the summer of 2021/2022, as part of the Brazilian Antarctic Expedition, we collected and examined a total of 315 fecal samples to target these respiratory viruses. Although we did not detect the viruses of interest during this particular expedition, previous research conducted by our team has shown the presence of the H11N2 subtype of influenza A virus in penguin fecal samples from the same region. Given the continuous emergence of new viral strains worldwide, it is crucial to maintain active surveillance in the area, contributing to strengthening integrated One Health surveillance efforts.

Multicenter study to describe viral etiologies, clinical profiles, and outcomes of hospitalized children with severe acute respiratory infections, Egypt 2022

In late 2022, severe acute respiratory infections (SARI) surveillance reported an abrupt increase in non-COVID-19 infections among children after three years of drastic reductions. Signals of increased absenteeism due to respiratory symptoms among primary and preparatory school children were detected by Event-Based Surveillance. We conducted a hospital-based survey of children who were admitted with SARI to identify the causative pathogen(s) and estimate the burden of infection. A survey was conducted among children < 16 years in 21 referral hospitals in the three governorates with the highest SARI rates. Patients' demographics, clinical symptoms, and severity were collected from medical records using a line list. Patients were swabbed and tested for a panel of 33 respiratory pathogens by RT-PCR at the Central Laboratory in Cairo. Descriptive data analysis was performed for demographic data. Patients' characteristics were compared by causative agents' clinical picture and severity using Chi2 with a p < 0.05 significance. Overall, 317 patients were enrolled, 58.3% were ≤ 1 year of age, 61.5% were males. Of 229 (72.7%) of positively tested patients, viruses caused 92.1% including RSV 63.8%, Rhinovirus 10.0%, Influenza 9.2%, Adenovirus 5.2%, and 1.3% co-infected with two viruses. Bacteria caused 3.5% of cases and 4.4% had mixed viral-bacterial infections. Rhinovirus was the most common cause of death among children with SARI, followed by RSV (8.7% and 1.4%), whereas influenza and Adenovirus did not result in any deaths. Patients with viral-bacterial infections are more likely to be admitted to ICU and die at the hospital than bacterial or viral infections (60% and 20% vs. 31.8% and 1.9% vs. 12.5% and 12.5%, p < 0.001). Viruses particularly RSV are the leading cause of SARI causing significant health problem among children < 16 years in Egypt. Bacterial on top of viral infection can worsen disease courses and outcomes. Studies are required to estimate the SARI burden accurately among Egyptian children and a comprehensive approach tailored to Egypt is necessary to reduce its burden.

Influenza vaccination in children with pulmonary disease during the COVID-19 pandemic

INTRODUCTION

Influenza is associated with considerable respiratory morbidity and mortality. Healthcare authorities recommend immunization of all children as vaccinations protect vulnerable populations, minimize influenza triggered asthma attacks, and reduced the burden of respiratory illnesses during the SARS-CoV-2 pandemic. Medical professionals should counsel parents of children with chronic lung disease to receive annual influenza vaccinations as part of supportive care. We aimed to describe adherence to influenza vaccination in respiratory patients and identify potential reasons for non-vaccination.

METHODS

This study included questionnaires reviewing personal experience and beliefs regarding influenza vaccination, provided by parents of patients who visited the Pediatric Pulmonary Institute at Schneider Children's Medical Center with their children, during March-August 2021.

RESULTS

Of 198 parents who completed our questionnaire, 114 (57.3 %) vaccinated their children against influenza during that year. Average age was 6.9 ± 4.5 years. Demographic data were similar between the vaccinated and unvaccinated groups. Influenza vaccination rates differed significantly between parents who received an explanation from their primary physician and those who did not (65.4 % vs. 43.7 %, respectfully, p = 0.003), and parents who received explanations from a pulmonary specialist and those who did not (77.3 % vs. 48.8 %, respectively, p = 0.004). The combined recommendation of a primary physician and pulmonologist translated to a significantly higher vaccination rate among those who received such recommendations, as compared to those who did not (p < 0.001). Parents who believed in vaccine efficacy and safety were more likely to vaccinate their children (p < 0.001). Factors significantly affecting the decision of the parents to have their child vaccinated were their knowledge, beliefs, and conceptions about the vaccine.

CONCLUSIONS

Pediatric respiratory patients' influenza vaccination rate was 57 %. Major factors encouraging vaccination were correct parental knowledge and receiving recommendations from their primary physician\pulmonologist. This emphasizes the need for providing patients with information, by first explaining the vaccine's importance to physicians.

Obesity amplifies influenza virus-driven disease severity in male and female mice

Influenza virus-induced respiratory pneumonia remains a major public health concern. Obesity, metabolic diseases, and female sex are viewed as independent risk factors for worsened influenza virus-induced lung disease severity. However, lack of experimental models of severe obesity in female mice limits discovery-based studies. Here, via utility of thermoneutral housing (30 °C) and high-fat diet (HFD) feeding, we induced severe obesity and metabolic disease in female C57BL/6 mice and compared their responses to severely obese male C57BL/6 counterparts during influenza virus infection. We show that lean male and female mice have similar lung edema, inflammation, and immune cell infiltration during influenza virus infection. At standard housing conditions, HFD-fed male, but not female, mice exhibit severe obesity, metabolic disease, and exacerbated influenza disease severity. However, combining thermoneutral housing and HFD feeding in female mice induces severe obesity and metabolic disease, which is sufficient to amplify influenza virus-driven disease severity to a level comparable to severely obese male counterparts. Lastly, increased total body weights of male and female mice at time of infection correlated with worsened influenza virus-driven disease severity metrics. Together, our findings confirm the impact of obesity and metabolic disease as key risk factors to influenza disease severity and present a novel mouse experimental model suitable for future mechanistic interrogation of sex, obesity, and metabolic disease traits in influenza virus-driven disease severity.

Systemic perturbations in amino acids/amino acid derivatives and tryptophan pathway metabolites associated with murine influenza A virus infection

BACKGROUND

Influenza A virus (IAV) is the only influenza virus causing flu pandemics (i.e., global epidemics of flu disease). Influenza (the flu) is a highly contagious disease that can be deadly, especially in high-risk groups. Worldwide, these annual epidemics are estimated to result in about 3 to 5 million cases of severe illness and in about 290,000 to 650,000 respiratory deaths. We intend to reveal the effect of IAV infection on the host's metabolism, immune response, and neurotoxicity by using a mouse IAV infection model.

METHODS

51 metabolites of murine blood plasma (33 amino acids/amino acid derivatives (AADs) and 18 metabolites of the tryptophan pathway) were analyzed by using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry with Electrospray Ionization at the acute (7 days post-infection (dpi)), resolution (14 dpi), and recovery (21 dpi) stages of the virus infection in comparison with controls.

RESULTS

Among the 33 biogenic amino acids/AADs, the levels of five amino acids/AADs (1-methylhistidine, 5-oxoproline, α-aminobutyric acid, glutamine, and taurine) increased by 7 dpi, whereas the levels of ten amino acids/AADs (4-hydroxyproline, alanine, arginine, asparagine, cysteine, citrulline, glycine, methionine, proline, and tyrosine) decreased. By 14 dpi, the levels of one AAD (3-methylhistidine) increased, whereas the levels of five amino acids/AADs (α-aminobutyric acid, aminoadipic acid, methionine, threonine, valine) decreased. Among the 18 metabolites from the tryptophan pathway, the levels of kynurenine, quinolinic acid, hydroxykynurenine increased by 7 dpi, whereas the levels of indole-3-acetic acid and nicotinamide riboside decreased.

CONCLUSIONS

Our data may facilitate understanding the molecular mechanisms of host responses to IAV infection and provide a basis for discovering potential new mechanistic, diagnostic, and prognostic biomarkers and therapeutic targets for IAV infection.

Suitability of Polymyxin B as a Mucosal Adjuvant for Intranasal Influenza and COVID-19 Vaccines

Polymyxin B (PMB) is an antibiotic that exhibits mucosal adjuvanticity for ovalbumin (OVA), which enhances the immune response in the mucosal compartments of mice. Frequent breakthrough infections of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants indicate that the IgA antibody levels elicited by the mRNA vaccines in the mucosal tissues were insufficient for the prophylaxis of this infection. It remains unknown whether PMB exhibits mucosal adjuvanticity for antigens other than OVA. This study investigated the adjuvanticity of PMB for the virus proteins, hemagglutinin (HA) of influenza A virus, and the S1 subunit and S protein of SARS-CoV-2. BALB/c mice immunized either intranasally or subcutaneously with these antigens alone or in combination with PMB were examined, and the antigen-specific antibodies were quantified. PMB substantially increased the production of antigen-specific IgA antibodies in mucosal secretions and IgG antibodies in plasma, indicating its adjuvanticity for both HA and S proteins. This study also revealed that the PMB-virus antigen complex diameter is crucial for the induction of mucosal immunity. No detrimental effects were observed on the nasal mucosa or olfactory bulb. These findings highlight the potential of PMB as a safe candidate for intranasal vaccination to induce mucosal IgA antibodies for prophylaxis against mucosally transmitted infections.

Diatomic iron nanozyme with lipoxidase-like activity for efficient inactivation of enveloped virus

Enveloped viruses encased within a lipid bilayer membrane are highly contagious and can cause many infectious diseases like influenza and COVID-19, thus calling for effective prevention and inactivation strategies. Here, we develop a diatomic iron nanozyme with lipoxidase-like (LOX-like) activity for the inactivation of enveloped virus. The diatomic iron sites can destruct the viral envelope via lipid peroxidation, thus displaying non-specific virucidal property. In contrast, natural LOX exhibits low antiviral performance, manifesting the advantage of nanozyme over the natural enzyme. Theoretical studies suggest that the Fe-O-Fe motif can match well the energy levels of Fe2 minority β-spin d orbitals and pentadiene moiety π* orbitals, and thus significantly lower the activation barrier of cis,cis-1,4-pentadiene moiety in the vesicle membrane. We showcase that the diatomic iron nanozyme can be incorporated into air purifier to disinfect airborne flu virus. The present strategy promises a future application in comprehensive biosecurity control.

Distinguishing Swine Flu (H1N1) from COVID-19: Clinical, Virological, and Immunological Perspectives

This article provides an in-depth examination on the differences between the influenza A strain, H1N1 (also called Swine Flu) and Covid-19 focusing on the immune response and clinical symptoms. Flu symptoms due to influenza A strain, H1N1, were initially discovered in 2009. This variant of influenza A is believed to have emerged through reassortment, a process where the resulting virus inherits gene segments from each of its parental viruses. This reassortment event has resulted in a variant with altered characteristics, potentially affecting the level of immunity in humans. The symptoms of this strain typically manifest 1-4 days after exposure and include fever, cough, sore throat, runny/stuffy nose, body aches, fatigue, and gastrointestinal symptoms such as diarrhea. The transmission dynamics of this new variant, including human-to-human transmission, are still under investigation by health authorities. Individuals with weakened immune systems are generally more susceptible to severe illness. Risk factors associated with swine flu can include older adults, young children, pregnant women, and individuals with obesity. Historical variants of swine flu, such as the 2015 variant in India, have been associated with significant case numbers and deaths, often due to respiratory failure. Since the epidemic of Covid-19 due to SARS-CoV2 in early 2020, several symptoms of COVID-19 and swine flu overlap. In this article, we critically reviewed the differences and similarities in the immune response and clinical symptoms due to H1N1 virus and SARS-CoV2 in human.