Epidemiology and burden of influenza in healthy children aged 6 to 35 months: analysis of data from the placebo arm of a phase III efficacy trial

Trends in Influenza and Related Health Resource Use During 2005-2021 Among Children in Japan

BACKGROUND

To determine the epidemiological trends in pediatric influenza and changes in healthcare resource use from 2005 to 2021 using nationally representative outpatient database in Japan.

METHODS

We conducted a retrospective cohort study consisting of 3.5 million children with 177 million person-months during 2005-2021 using Japan Medical Data Center claims database in Japan. We investigated trends in incidence rates of influenza and changes in healthcare resource use (eg, use of antivirals) over 17 years. Generalized estimation equations were used to investigate the impact of the 2009 influenza pandemic and the coronaviral disease 2019 (COVID-19) pandemic on incidence rates of influenza and related healthcare utilization.

RESULTS

Annual incidence rates of influenza were estimated at 55 cases per 1000 person-years with a 93% relative increase [95% confidence interval (CI): 80%-107%] during the 2009 influenza pandemic and a 99.4% relative reduction (95% CI: 99.3%-99.4%) during the COVID-19 pandemic. Similar patterns were observed for health resource use, total healthcare costs, admission rates and antiviral agent use. Approximately 80% of children with influenza received prescriptions for antivirals. The most prescribed antivirals were oseltamivir, but we observed a temporal increase in zanamivir use during 2007-2009, an increasing trend in laminamivir use during 2010-2017, a temporal increase in baloxavir use in 2018. Symptomatic medications with serious side effects (codeine, salicylate, sedative antihistamine) showed decreasing trends over the study period.

CONCLUSIONS

Influenza incidence and healthcare resource use were largely affected by the 2009 influenza pandemic and the COVID-19 pandemic. Our study indicates improvement of quality in healthcare delivered to children.

XiaoEr LianHuaQinqGan alleviates viral pneumonia in mice infected by influenza A and respiratory syncytial viruses

CONTEXT

Xiaoer lianhuaqinqgan (XELH), developed based on Lianhua Qingwen (LHQW) prescription, contains 13 traditional Chinese medicines. It has completed the investigational new drug application to treat respiratory viral infections in children in China.

OBJECTIVE

This study demonstrates the pharmacological effects of XELH against viral pneumonia.

MATERIALS AND METHODS

The antiviral and anti-inflammatory effects of XELH were investigated in vitro using H3N2-infected A549 and LPS-stimulated RAW264.7 cells and in vivo using BALB/c mice models of influenza A virus (H3N2) and respiratory syncytial virus (RSV)-infection. Mice were divided into 7 groups (n = 20): Control, Model, LHQW (0.5 g/kg), XELH-low (2 g/kg), XELH-medium (4 g/kg), XELH-high (8 g/kg), and positive drug (20 mg/kg oseltamivir or 60 mg/kg ribavirin) groups. The anti-inflammatory effects of XELH were tested in a rat model of LPS-induced fever and a mouse model of xylene-induced ear edoema.

RESULTS

In vitro, XELH inhibited the pro-inflammatory cytokines and replication of H1N1, H3N2, H1N1, FluB, H9N2, H6N2, H7N3, RSV, and HCoV-229E viruses, with (IC₅₀ 47.4, 114, 79, 250, 99.2, 170, 79, 62.5, and 93 μg/mL, respectively). In vivo, XELH reduced weight loss and lung index, inhibited viral replication and macrophage M1 polarization, ameliorated lung damage, decreased inflammatory cell infiltration and pro-inflammatory cytokines expression in lung tissues, and increased the CD4⁺/CD8⁺ ratio. XELH inhibited LPS-induced fever in rats and xylene-induced ear edoema in mice.

CONCLUSION

XELH efficacy partially depends on integrated immunoregulatory effects. XELH is a promising therapeutic option against childhood respiratory viral infections.

Maternal immune protection against infectious diseases

The maternal immune system protects developing offspring against pathogens before birth via transplacental transfer and after birth through secreted milk. This transferred maternal immunity influences each generation's susceptibility to infections and responsiveness to immunization. Thus, boosting immunity in the maternal-neonatal dyad is a potentially valuable public health strategy. Additionally, at critical times during fetal and postnatal development, environmental factors and immune stimuli influence immune development. These "windows of opportunity" offer a chance to identify both risk and protective factors that promote long-term health and limit disease. Here, we review pre- and postpartum maternal immune factors that protect against infectious agents in offspring and how they may shape the infant's immune landscape over time. Additionally, we discuss the influence of maternal immunity on the responsiveness to immunization in early life. Lastly, when maternal factors are insufficient to prevent neonatal infectious diseases, we discuss pre- and postnatal therapeutic strategies for the maternal-neonatal dyad.

Dissecting Fc signatures of protection in neonates following maternal influenza vaccination in a placebo-controlled trial

Influenza is an important cause of illness and morbidity for infants. Seasonal influenza vaccination during pregnancy aims to provide protection to mothers, but it can also provide immunity to infants. The precise influence of maternal vaccination on immunity in infants and how vaccine-elicited antibodies provide protection in some but not all infants is incompletely understood. We comprehensively profiled the transfer of functional antibodies and defined humoral factors contributing to immunity against influenza in a clinical trial of maternal influenza vaccination. Influenza-specific antibody subclass levels, Fc ɣ receptor (FCGR) binding levels, and antibody-dependent innate immune functions were all profiled in the mothers during pregnancy and at birth, as well as in cord blood. Vaccination increased influenza-specific antibody levels, antibody binding to FCGR, and specific antibody-dependent innate immune functions in both maternal and cord blood, with FCGR binding most enhanced via vaccination. Influenza-specific FCGR binding levels were lower in cord blood of infants who subsequently developed influenza infection. Collectively these data suggest that in addition to increased antibody amounts, the selective transfer of FCGR-binding antibodies contributes to the protective immune response in infants against influenza.

Evaluation of Influenza Patients Admitted in 2019–2020 Flu Season

Objective Influenza viruses are among the most common respiratory pathogens for all age groups, and may cause seasonal outbreaks. The aim of our study was to describe the clinical characteristics of influenza cases in the 2019–2020 flu season and to study the risk factors for hospital admission and complications.

Methods This was a retrospective study in 251 children (group 1: nonhospitalized; group 2: hospitalized) with influenza in the 2019–2020 flu season. Data on demographic features, influenza type, complaints, complications, and hospitalization length were collected and recorded.

Results Influenza A was detected in 199 (79.3%) patients, and influenza B was detected in 52 (20.7%); 43.4% of patients were girls and 56.6% were boys. The mean age of the patients was 3.91 ± 3.3 years (16 days to 18 years). A total of 52 (20.7%) patients were hospitalized. The age of the patients in group 2 was lower than that in group 1 (3.1 vs. 4.2 years, p = 0.03). Group 2 patients were more likely to have creatine kinase (CK) elevation, febrile seizures, and physical examination abnormalities. Group 2 patients were also more likely to have influenza A. Patients with febrile seizures, chronic diseases, abnormal physical examination findings, developed complications, and additional drug use apart from oseltamivir in the treatment were also more likely to require hospitalization.

Conclusion Infants and children with chronic diseases, history of febrile seizures, complications, and the use of drugs other than antiviral drugs should be carefully evaluated in case they need hospitalization. Increasing vaccination rates, initiation of antiviral treatment for selected patients, and close monitoring of patients in risk groups can decrease morbidity and mortality. Myalgias are a common complaint in patients with acute influenza infection. Previous studies suggest CK measurement be part of the work-up for the hospitalized patient with acute influenza infection.

Postbiotics against Pathogens Commonly Involved in Pediatric Infectious Diseases

The Sustainable Development goals for 2020 included reducing all causes associated with infant and perinatal mortality in their priorities. The use of compounds with bioactive properties has been proposed as a therapeutic strategy due to their stimulating effect on the host's immune system. Additionally, biotherapeutic products such as postbiotics, tentatively defined as compounds produced during a fermentation process that support health and well-being, promote intestinal barrier integrity without posing considerable risks to children's health. Although this is a concept in development, there are increasing studies in the field of nutrition, chemistry, and health that aim to understand how postbiotics can help prevent different types of infections in priority populations such as minors under the age of five. The present review aims to describe the main mechanisms of action of postbiotics. In addition, it presents the available current evidence regarding the effects of postbiotics against pathogens commonly involved in pediatric infections. Postbiotics may constitute a safe alternative capable of modulating the cellular response and stimulating the host's humoral response.

Betrachtung der Pandemie Phase 3 – „mitigation“ – vom Endpunkt Hospitalisation her

Hintergrund

Die Phase 3 – „mitigation“ – der jetzigen Pandemie durch das SARS-CoV‑2 steht nun auch in Deutschland unmittelbar bevor. Da es aufgrund der hohen Komplexität sehr viel zu beachten gibt, ist Vereinfachung dringend geboten, nicht zuletzt auch, um den Fokus auf die wichtigen Dinge nicht aus den Augen zu verlieren.

Methode

Die Phase 3 vom Endpunkt, und zwar der stationären Behandlung (Hospitalisation), her zu betrachten, soll den Blick auf die Einflussgrößen flussaufwärts schärfen. Auf der Grundlage einer simplifizierten Modellierung mit Hilfe von angenäherten und plausiblen Parametern für die Infektionsrate (attack rate), hier als AR(gesamt) bezeichnet, die Rate für eine stationäre Aufnahme – AR(stationär) und die Rate für eine intensivmedizinische Behandlung – AR(intensiv), werden als SOLL mit den verfügbaren Ressourcen, sprich Betten im allgemeinstationären und intensivmedizinischen Bereich, IST, verglichen. Die Berechnungen werden populations-bezogen je für den Landkreis Plön und die Metropolregion Kiel zusammen mit Kreis Plön ausgeführt.

Ergebnisse

Da in den bisherigen Kohorten die Prozentsätze der notwendigen Maßnahmen überschätzt werden, sollte eine deutlich niedrigere AR(stationär) und AR(intensiv) zu erwarten sein. Eine AR(stationär) von 10 % wäre für den Flächenkreis Plön nicht abzubilden, eine mit 5 % sehr wohl. In der regionalen Betrachtung mit dem Universitätsklinikum SH, Standort Kiel, lässt sich sogar eine AR(stationär) von bis zu 10 % abbilden, insbesondere auch eine AR(intensiv) von 3 %. Allerdings ist die Anflutungsgeschwindigkeit von den epidemiologischen Gegenmaßnahmen und dem Einweisungsverhalten abhängig. Die verfügbare Bettenanzahl wird von der freigemachten Bettenzahl und der Liegedauer bestimmt; letztere von Alter und Vorerkrankungen der Patienten.

Schlussfolgerungen

Ein Systemversagen sollte durch Klarheit über die entscheidenden Parameter und ihrer Einflussgrößen vermieden werden. Die regionale Betrachtung der Versorgung ist wichtig und sollte von einem Bettenkoordinator gesteuert werden. Auf die enge Zusammenarbeit im Gesamtversorgungssystem im Schulterschluss mit den Gesundheitsämtern kommt es an.

Recombinant Measles AIK-C Vaccine Strain Expressing Influenza HA Protein

Recombinant measles AIK-C vaccine expressing the hemagglutinin (HA) protein of influenza A/Sapporo/107/2013(H1N1pdm) (MVAIK/PdmHA) was constructed. Measles particle agglutination (PA) and influenza hemagglutinin inhibition (HI) antibodies were induced in cotton rats immunized with MVAIK/PdmHA. Cotton rats immunized with two doses of the HA split vaccine were used as positive controls, and higher HI antibodies were detected 3 weeks after the first dose. Following the challenge of A/California/07/2009(H1N1pdm), higher viral loads (10⁷ TCID50/g) were detected in the lung homogenates of cotton rats immunized with the empty vector (MVAIK) or control groups than those immunized with MVAIK/Pdm HA (10³ TCID50/g) or the group immunized with HA split vaccine (10⁵ TCID50/g). Histopathologically, destruction of the alveolar structure, swelling of broncho-epithelial cells, and thickening of the alveolar wall with infiltration of inflammatory cells and HA antigens were detected in lung tissues obtained from non-immunized rats and those immunized with the empty vector after the challenge, but not in those immunized with the HA spilt or MVAIK/PdmHA vaccine. Lower levels of IFN-α, IL-1β, and TNF-α mRNA, and higher levels of IFN-γ mRNA were found in the lung homogenates of the MVAIK/PdmHA group. Higher levels of IFN-γ mRNA were detected in spleen cell culture from the MVAIK/PdmHA group stimulated with UV-inactivated A/California/07/2009(H1N1pdm). In conclusion, the recombinant MVAIK vaccine expressing influenza HA protein induced protective immune responses in cotton rats.

Immune Pressure on Polymorphous Influenza B Populations Results in Diverse Hemagglutinin Escape Mutants and Lineage Switching

Mutations arise in the genomes of progeny viruses during infection. Mutations that occur in epitopes targeted by host antibodies allow the progeny virus to escape the host adaptive, B-cell mediated antibody immune response. Major epitopes have been identified in influenza B virus (IBV) hemagglutinin (HA) protein. However, IBV strains maintain a seasonal presence in the human population and changes in IBV genomes in response to immune pressure are not well characterized. There are two lineages of IBV that have circulated in the human population since the 1980s, B-Victoria and B-Yamagata. It is hypothesized that early exposure to one influenza subtype leads to immunodominance. Subsequent seasonal vaccination or exposure to new subtypes may modify subsequent immune responses, which, in turn, results in selection of escape mutations in the viral genome. Here we show that while some mutations do occur in known epitopes suggesting antibody escape, many mutations occur in other parts of the HA protein. Analysis of mutations outside of the known epitopes revealed that these mutations occurred at the same amino acid position in viruses from each of the two IBV lineages. Interestingly, where the amino acid sequence differed between viruses from each lineage, reciprocal amino acid changes were observed. That is, the virus from the Yamagata lineage become more like the Victoria lineage virus and vice versa. Our results suggest that some IBV HA sequences are constrained to specific amino acid codons when viruses are cultured in the presence of antibodies. Some changes to the known antigenic regions may also be restricted in a lineage-dependent manner. Questions remain regarding the mechanisms underlying these results. The presence of amino acid residues that are constrained within the HA may provide a new target for universal vaccines for IBV.

Immunogenicity and safety of Quadrivalent Influenza HA vaccine in Indonesian children: An open-labeled, bridging, clinical study

BACKGROUND

Influenza B (Yamagata/Victoria lineage) can cause severe forms of respiratory infection among the pediatric population as well as influenza A strains (H3N2/H1N1). Vaccination against all four strains is required to prevent infection and severe outcome. This study is the first study to assess the immunogenicity of Quadrivalent Influenza HA vaccine (QIV) and ascertain safety among children in Indonesia.

METHODS

This is an open labeled, single arm, bridging clinical study involving unprimed healthy children 6-35 months of age (Group I) and 3-8 years of age (Group II). Subjects on both groups receiving two doses of QIV with a 28 days interval. Serology tests were performed on baseline and 28 days post-vaccination. Hemagglutination inhibition antibody titers were analyzed for Geometric Mean Titer (GMT), seroprotection, and seroconversion rates. Solicited reactions, unsolicited adverse events, and serious adverse events were observed up to 28 days post-vaccination.

RESULTS

Out of 270 subjects enrolled, 269 subjects completed the study. Immunogenicity analysis were evaluated on 254 subjects. Seroprotection rates were ≥85% for all vaccine strains in both groups. Seroconversion of more than 4 folds for all strains occurred in both groups post-vaccination. In Group I, the increase of GMT for A/H1N1, A/H3N2, B/Texas, and B/Phuket was 12.5, 14.5, 8.2, and 6.4 folds, respectively. In Group II the increase of GMT for A/H1N1, A/H3N2, B/Texas, and B/Phuket was 14, 17, 10, and 8 folds, respectively. The majority of local adverse events (AEs) after the first and second immunizations were immediate injection-site pain (10.4% and 12.6%). The majority of systemic AEs after the first and second immunizations were delayed unsolicited AEs (14.8% and 14.9%). No vaccine-related serious adverse events or deaths were reported.

CONCLUSION

The investigational QIV was immunogenic with an acceptable safety profile in children 6 months to 8 years of age.

CLINICAL TRIAL REGISTRATION

NCT03336593.

Influenza A and B in a cohort of outpatient children and adolescent with influenza like-illness during two consecutive influenza seasons

INTRODUCTION

Influenza is an important cause of morbimortality worldwide. Although people at the extremes of age have a greater risk of complications, influenza has been more frequently investigated in the elderly than in children, and inpatients than outpatients. Yearly vaccination with trivalent or quadrivalent vaccines is the main strategy to control influenza.

OBJECTIVES

Determine the clinical and molecular characteristics of influenza A and B infections in children and adolescents with influenza-like illness (ILI).

METHODS

A cohort of outpatient children and adolescents with ILI was followed for 20 months. Influenza was diagnosed with commercial multiplex PCR platforms.

RESULTS

179 patients had 277 episodes of ILI, being 79 episodes of influenza A and 20 episodes of influenza B. Influenza A and B cases were mild and had similar presentation. Phylogenetic tree of influenza B viruses showed that 91.6% belonged to the B/Yamagata lineage, which is not included in trivalent vaccines.

CONCLUSIONS

Influenza A and B are often detected in children and adolescents with ILI episodes, with similar and mild presentation in outpatients. The mismatch between the circulating influenza viruses and the trivalent vaccine offered in Brazil may have contributed to the high frequency of influenza A and B in this population.

Quadrivalent Influenza Vaccine Prevents Illness and Reduces Healthcare Utilization Across Diverse Geographic Regions During Five Influenza Seasons: A Randomized Clinical Trial

BACKGROUND

We evaluated an inactivated quadrivalent influenza vaccine (IIV4) in children 6-35 months of age in a phase III, observer-blind trial.

METHODS

The aim of this analysis was to estimate vaccine efficacy (VE) in preventing laboratory-confirmed influenza in each of 5 independent seasonal cohorts (2011-2014), as well as vaccine impact on healthcare utilization in 3 study regions (Europe/Mediterranean, Asia-Pacific and Central America). Healthy children were randomized 1:1 to IIV4 or control vaccines. VE was estimated against influenza confirmed by reverse transcription polymerase chain reaction on nasal swabs. Cultured isolates were characterized as antigenically matched/mismatched to vaccine strains.

RESULTS

The total vaccinated cohort included 12,018 children (N = 1777, 2526, 1564, 1501 and 4650 in cohorts 1-5, respectively). For reverse transcription polymerase chain reaction confirmed influenza of any severity (all strains combined), VE in cohorts 1-5 was 57.8%, 52.9%, 73.4%, 30.3% and 41.4%, respectively, with the lower limit of the 95% confidence interval >0 for all estimates. The proportion of vaccine match for all strains combined in each cohort was 0.9%, 79.3%, 72.5%, 24.1% and 28.6%, respectively. Antibiotic use associated with influenza illness was reduced with IIV4 by 71% in Europe, 36% in Asia Pacific and 59% in Central America.

CONCLUSIONS

IIV4 prevented influenza in children 6-35 months of age in each of 5 separate influenza seasons in diverse geographical regions. A possible interaction between VE, degree of vaccine match and socioeconomic status was observed. The IIV4 attenuated the severity of breakthrough influenza illness and reduced healthcare utilization, particularly antibiotic use.

Detection and clinical characteristics analysis of respiratory viruses in hospitalized children with acute respiratory tract infections by a GeXP-based multiplex-PCR assay

Background

The information regarding viral epidemiology and clinical characteristics in hospitalized children with acute respiratory tract infection (ARTI) in central Fujian is limited. In this study, we aimed at analyzing the viral epidemiology and clinical characteristics of ARTI in hospitalized children admitted to The First Affiliated Hospital of Fujian Medical University.

Methods

Cohort of 386 hospitalized children (31 days to 15 years) diagnosed with ARTI admitted to the Department of Pediatrics from January 1, 2018, to December 31, 2018, was enrolled in this study. Nasopharyngeal swab or sputum samples on the day of hospitalization were tested for 11 viruses via a GeXP‐based multiplex‐PCR assay. The viral profiles and clinical characteristics were analyzed.

Results

The overall positive rate of the samples was 43.26% (167/386). Among the 167 positive samples, 134 (80.24%, 134/167) had a single virus and 33 (19.76%, 33/167) had multiple viruses. There was a significant difference in the frequency of single vs mixed infections among positive samples (80.24% vs 19.76%; χ² = 122.168, P = .000) as well as among the total examined samples (34.72% vs 8.55%; χ² = 77.945, P = .000). Human rhinovirus was the most prevalent virus (17.36%, 67/386), followed by influenza A (5.96%, 23/386) and human adenovirus (5.70%, 22/386). There was no significant difference in the etiological distribution of viral pathogens between males and females (χ² = 0.480, P = .489). Viral infections were more likely to occur in the winter‐spring months than in the summer‐autumn months (52.51% vs 33.53%, χ² = 13.830, P = .000).

Conclusions

The GeXP‐based multiplex PCR is an accurate and high‐throughput assay allows us to quickly detect multiple respiratory viruses simultaneously in pediatric patients. Our study provides information on the viral profiles and clinical characteristics in hospitalized children with ARTI, which would help better effective prevention strategies.