Contribution of influenza viruses to medically attended acute respiratory illnesses in children in high-income countries: a meta-analysis

Clinical characteristics and assessment of risk factors in patients with influenza A-induced severe pneumonia after the prevalence of SARS-CoV-2

Purpose

The aim of this study is to describe the novel epidemiological and clinical characteristics of influenza A-induced severe pneumonia occurring after the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and to further assess its potential risk factors for mortality.

Methods

We retrospectively studied the consecutive case series of 30 patients with confirmed influenza A-induced severe pneumonia treated in the intensive care unit at Dazhou Central Hospital in Sichuan, China, from March 1 to April 30, 2023. Logistic regression was used to analyze the independent risk factors, and receiver operating characteristic (ROC) curves were applied to evaluate the predictive efficacy of associated risk factors for mortality.

Results

The mortality rate was 33.3% in this study. Independent risk factors for mortality of patients were acute respiratory distress syndrome (ARDS) (p = 0.044) and septic shock (p = 0.012). ROC statistics for ARDS and septic shock to predict mortality in patients with influenza A-induced severe pneumonia demonstrated an area under the curve of 0.800 (sensitivity 80.0%, specificity 80.0%) and 0.825 (sensitivity 70.0%, specificity 95.0%), respectively.

Conclusion

ARDS and septic shock were the independent risk factors for mortality in patients with influenza A-induced severe pneumonia following the end of the SARS-CoV-2 pandemic. But high level of next generation sequencing reads Aspergillus coinfection, and comorbidities did not increase death risk of the study population.

Residential exposure to mold, dampness, and indoor air pollution and risk of respiratory tract infections: a study among children ages 11 and 12 in the Danish National Birth Cohort

BACKGROUND

The burden of respiratory tract infections (RTIs) is high in childhood. Several residential exposures may affect relative rates.

OBJECTIVES

To determine risk of RTIs in children ages 11 and 12 by residential exposures.

METHODS

We included children in the Danish National Birth Cohort (DNBC) at ages 11 and 12. We estimated incidence risk ratios (IRR) and 95% confidence intervals (CI) for counts of RTIs within the last year by exposure to mold/dampness, gas stove usage, summer and winter candle-burning, fireplace usage, cats and dogs indoors, and farmhouse living. We also estimated IRR and 95% CI for RTIs for predicted scores of four extracted factors ('owned house', 'mold and dampness', 'candles', and 'density') from exploratory factor analyses (EFA).

RESULTS

We included 42 720 children with complete data. Mold/dampness was associated with all RTIs (common cold: IRRadj 1.09[1.07, 1.12]; influenza: IRRadj 1.10 [1.05, 1.15]; tonsillitis: IRRadj 1.19 [1.10, 1.28]; conjunctivitis: IRRadj 1.16 [1.02, 1.32]; and doctor-diagnosed pneumonia: IRRadj 1.05 [0.90, 1.21]), as was the EFA factor 'mold/dampness' for several outcomes. Gas stove usage was associated with conjunctivitis (IRRadj 1.25 [1.05, 1.49]) and with doctor-diagnosed pneumonia (IRRadj 1.14 [0.93, 1.39]). Candle-burning during summer, but not winter, was associated with several RTIs, for tonsillitis in a dose-dependent fashion (increasing weekly frequencies vs. none: [IRRadj 1.06 [0.98, 1.14], IRRadj 1.16 [1.04, 1.30], IRRadj 1.23 [1.06, 1.43], IRRadj 1.29 [1.00, 1.67], and IRRadj 1.41 [1.12, 1.78]).

CONCLUSION

Residential exposures, in particular to mold and dampness and to a lesser degree to indoor combustion sources, are related to the occurrence of RTIs in children.

Protocol for establishing a model for integrated influenza surveillance in Tamil Nadu, India

The potential for influenza viruses to cause public health emergencies is great. The World Health Organisation (WHO) in 2005 concluded that the world was unprepared to respond to an influenza pandemic. Available surveillance guidelines for pandemic influenza lack the specificity that would enable many countries to establish operational surveillance plans. A well-designed epidemiological and virological surveillance is required to strengthen a country's capacity for seasonal, novel, and pandemic influenza detection and prevention. Here, we describe the protocol to establish a novel mechanism for influenza and SARS-CoV-2 surveillance in the four identified districts of Tamil Nadu, India. This project will be carried out as an implementation research. Each district will identify one medical college and two primary health centres (PHCs) as sentinel sites for collecting severe acute respiratory infections (SARI) and influenza like illness (ILI) related information, respectively. For virological testing, 15 ILI and 10 SARI cases will be sampled and tested for influenza A, influenza B, and SARS-CoV-2 every week. Situation analysis using the WHO situation analysis tool will be done to identify the gaps and needs in the existing surveillance systems. Training for staff involved in disease surveillance will be given periodically. To enhance the reporting of ILI/SARI for sentinel surveillance, trained project staff will collect information from all ILI/SARI patients attending the sentinel sites using pre-tested tools. Using time, place, and person analysis, alerts for abnormal increases in cases will be generated and communicated to health authorities to initiate response activities. Advanced epidemiological analysis will be used to model influenza trends over time. Integrating virological and epidemiological surveillance data with advanced analysis and timely communication can enhance local preparedness for public health emergencies. Good quality surveillance data will facilitate an understanding outbreak severity and disease seasonality. Real-time data will help provide early warning signals for prevention and control of influenza and COVID-19 outbreaks. The implementation strategies found to be effective in this project can be scaled up to other parts of the country for replication and integration.

Spotlight influenza: Laboratory-confirmed seasonal influenza in people with acute respiratory illness: a literature review and meta-analysis, WHO European Region, 2004 to 2017

BackgroundAcross the World Health Organization European Region, there are few estimates of the proportion of people seeking medical care for influenza-like illness or acute respiratory infections and who have laboratory-confirmed seasonal influenza infection.MethodsWe conducted a meta-analysis of data extracted from studies published between 2004 and 2017 and from sentinel data from the European surveillance system (TESSy) between 2004 and 2018. We pooled within-season estimates by influenza type/subtype, setting (outpatient (OP)/inpatient (IP)) and age group to estimate the proportion of people tested who have laboratory-confirmed and medically-attended seasonal influenza in Europe.ResultsIn the literature review, the pooled proportion for all influenza types was 33% (95% confidence interval (CI): 30-36), higher among OP 36% (95% CI: 33-40) than IP 24% (95% CI: 20-29). Pooled estimates for all influenza types by age group were: 0-17 years, 26% (22-31); 18-64 years, 41% (32-50); ≥ 65 years, 33% (27-40). From TESSy data, 33% (31-34) of OP and 24% (21-27) of IP were positive. The highest proportion of influenza A was in people aged 18-64 years (22%, 16-29). By subtype, A(H1N1)pdm09 was highest in 18-64 year-olds (16%, 11-21%) whereas A(H3N2) was highest in those ≥ 65 years (10%, 2-22). For influenza B, the highest proportion of infections was in those aged 18-64 years (15%, 9-24).ConclusionsLaboratory-confirmed influenza accounted for approximately one third of all acute respiratory infections for which medical care was sought during the influenza season.

Analysis of MarketScan Data for Immunosuppressive Conditions and Hospitalizations for Acute Respiratory Illness, United States

Increasing use of immunosuppressive biologic therapies poses a challenge for infectious diseases. Immunosuppressed patients have a high risk for influenza complications and an impaired immune response to vaccines. The total burden of immunosuppressive conditions in the United States, including those receiving emerging biologic therapies, remains unknown. We used the national claims database MarketScan to estimate the prevalence of immunosuppressive conditions and risk for acute respiratory illnesses (ARIs). We studied 47.2 million unique enrollees, representing 115 million person-years of observation during 2012–2017, and identified immunosuppressive conditions in 6.2% adults 18–64 years of age and 2.6% of children <18 years of age. Among 542,105 ARI hospitalizations, 32% of patients had immunosuppressive conditions. The risk for ARI hospitalizations was higher among enrollees with immunosuppression than among nonimmunosuppressed enrollees. Future efforts should focus on developing improved strategies, including vaccines, for preventing influenza in immunosuppressed patients, who are an increasing population in the United States.

Subtype-specific Clinical Presentation, Medical Treatment and Family Impact of Influenza in Children 1-5 Years of Age Treated in Outpatient Practices in Germany During Three Postpandemic Years, 2013-2015

BACKGROUND

Limited data on the influenza burden in pediatric outpatients are available, especially regarding direct comparison of the cocirculating (sub)types A(H1N1)pdm09, A(H3N2) and B.

METHODS

Children 1-5 years of age, unvaccinated against influenza and presenting with febrile acute respiratory infections (ARIs), were enrolled in 33 pediatric practices in Germany from 2013 to 2015 (January-May). Influenza was confirmed by multiplex polymerase chain reaction from pharyngeal swabs and (sub)typed.

RESULTS

In 805 children with ARI, influenza was the most frequently detected respiratory virus (n = 305; 37.9%). Of 217 influenza patients included, 122 (56.2%) were infected with A(H3N2), 56 (25.8%) with A(H1N1)pdm09 and 39 (18.0%) with B. Median age was 3.7 years [interquartile range (IQR), 2.1-4.8]; 11% had underlying conditions. Median fever duration was 4 days (IQR, 3-5), and the disease duration was 9 days (IQR, 7-12). Most frequent diagnoses were pharyngitis (26%), bronchitis (18%) and acute otitis media (10%). Children received mainly antipyretics (86%) and adrenergic nasal drops/spray (53%); 9% received antibiotics and 3% oseltamivir. Thirty-six percent required at least 1 additional practice visit; 1% was hospitalized. Median absences from childcare were 5 days (IQR, 3-7); parents lost 4 workdays (IQR, 2-6). Symptoms, severity and impact on the family were largely unrelated to (sub)type. However, patients with A(H1N1)pdm09 had fewer underlying conditions (P = 0.017), whereas patients with B more often had pharyngitis (P = 0.022), acute otitis media (P = 0.012) and stenosing laryngotracheitis (P = 0.007).

CONCLUSIONS

Influenza was the most frequently detected viral pathogen in outpatient children with febrile, mostly uncomplicated ARI. In this setting, clinical manifestations and severity were similar across the (sub)types prevalent during the postpandemic seasons.

Severe Pneumonia Caused by Influenza A (H1N1) Virus Successfully Managed with Extracorporeal Life Support in a Comorbid Former Preterm Infant

Influenza A (H1N1) virus infection is a global health burden, leading to significant pediatric morbidity and mortality. Prematurity, young age and comorbidities are important risk factors for unfavorable outcomes. Preventive strategies, such as healthcare workers and household contacts vaccination as well as the implementation of infection control practices during the epidemic season, are crucial to protect the most vulnerable populations. Early diagnosis, timely administration of antiviral drugs and supportive therapy are crucial to lead to a complete recovery. When conventional treatment fails, extracorporeal life support (ECLS) may be employed. In neonates and young infants, this high-tech support is burdened by specific technical complexity. Despite the potential risks related to this aggressive approach, ECLS is a life-saving procedure in 65% of pediatric viral pneumonia and in 73% of sepsis cases. Here, we report the successful outcome of a 51-day formerly preterm infant, suffering from a surgical necrotizing enterocolitis (NEC), complicated with hospital-acquired pneumonia due to influenza A (H1N1) virus. She developed a severe respiratory failure, unresponsive to conventional therapy, and successfully treated with ECLS. To our knowledge, this is the first report on the use of ECLS in a formerly preterm infant, suffering from NEC complicated by influenza A (H1N1) virus infection.

Contribution of influenza viruses to medically attended acute respiratory illnesses in children in high-income countries: a meta-analysis

AIM

The burden of disease in children attributable to influenza viruses is difficult to quantify given the similarity of symptoms caused by infection due to influenza and other viruses. This uncertainty impacts clinical decision-making and estimates of burden. We aimed to systematically review the literature to determine the proportion of healthy children presenting for health care with an acute respiratory illness (ARI) who have laboratory-confirmed seasonal influenza (PROSPERO ID#CRD42014013896).

METHOD

We searched Ovid MEDLINE, EMBASE, Scopus, and references of included articles. We included studies that used polymerase chain reaction methods to test for influenza in healthy children aged ≤5 years who presented for health care in high-income countries with an influenza-like or ARI. A standardized form was used to collect data on positivity and other relevant study elements.

RESULTS

Seventeen studies covering 12 different influenza seasons were included. The proportion of influenza positivity ranged from 11% to 56%. Subgroup analyses were performed by influenza season, continent, healthcare setting, age group, and vaccination status. Higher influenza positivity was reported among children aged 3-5 years compared with children aged ≤2 years, and for unvaccinated children.

CONCLUSION

The minority of healthy patients aged ≤5 years with medically attended influenza-like or acute respiratory symptoms have laboratory-confirmed influenza virus infection, although this varied by influenza season. Prevention efforts should be targeted accordingly.

STATEMENT

Most influenza-like illnesses are not laboratory-confirmed and have similar clinical presentations. Consequently, the true contribution of influenza to acute respiratory infections in children remains uncertain. Our systematic review estimates that this proportion ranges from 11% to 56%. This finding can help both clinicians and public health professionals target prevention.