Severe Lower Respiratory Infection Research Articles

Evaluation of adenoviral vector Ad19a encoding RSV-F as novel vaccine against respiratory syncytial virus

Respiratory syncytial virus (RSV) is the leading cause of severe lower respiratory tract infections in infants and toddlers. Since natural infections do not induce persistent immunity, there is the need of vaccines providing long-term protection. Here, we evaluated a new adenoviral vector (rAd) vaccine based on the rare serotype rAd19a and compared the immunogenicity and efficacy to the highly immunogenic rAd5. Given as an intranasal boost in DNA primed mice, both vectors encoding the F protein provided efficient protection against a subsequent RSV infection. However, intramuscular immunization with rAd19a vectors provoked vaccine-enhanced disease after RSV infection compared to non-vaccinated animals. While mucosal IgA antibodies and tissue-resident memory T-cells in intranasally vaccinated mice rapidly control RSV replication, a strong anamnestic systemic T-cell response in absence of local immunity might be the reason for immune-mediated enhanced disease. Our study highlighted the potential benefits of developing effective mucosal against respiratory pathogens.

The actin-binding protein palladin associates with the respiratory syncytial virus matrix protein.

The respiratory syncytial virus (RSV) matrix (M) protein plays an important role in infection as it can interact with viral components as well as the host cell actin microfilaments. The M-actin interaction may play a role in facilitating the transportation of virion components to the apical surface, where RSV is released. We show that M protein's association with actin is facilitated by palladin, an actin-binding protein. Cells were infected with RSV or transfected to express full-length M as a green fluorescent protein (GFP)-tagged protein, followed by removal of nuclear and cytosolic proteins to enrich for cytoskeleton and its associated proteins. M protein was present in inclusion bodies tethered to microfilaments in infected cells. In transfected cells, GFP-M was presented close to microfilaments, without association, suggesting the possible involvement of an additional protein in this interaction. As palladin can bind to proteins that also bind actin, we investigated its interaction with M. Cells were co-transfected to express GFP-M and palladin as an mCherry fluorescent-tagged protein, followed by cytoskeleton enrichment. M and palladin were observed to colocalize towards microfilaments, suggesting that palladin is involved in the M-actin interaction. In co-immunoprecipitation studies, M was found to associate with two isoforms of palladin, of 140 and 37 kDa. Interestingly, siRNA downregulation of palladin resulted in reduced titer of released RSV, while cell associated RSV titer increased, suggesting a role for palladin in virus release. Together, our data show that the M-actin interaction mediated by palladin is important for RSV budding and release.IMPORTANCERespiratory syncytial virus is responsible for severe lower respiratory tract infections in young children under 5 years old, the elderly, and the immunosuppressed. The interaction of the respiratory syncytial virus matrix protein with the host actin cytoskeleton is important in infection but has not been investigated in depth. In this study, we show that the respiratory syncytial virus matrix protein associates with actin microfilaments and the actin-binding protein palladin, suggesting a role for palladin in respiratory syncytial virus release. This study provides new insight into the role of the actin cytoskeleton in respiratory syncytial virus infection, a key host-RSV interaction in assembly. Understanding the mechanism by which the RSV M protein and actin interact will ultimately provide a basis for the development of therapeutics targeted at RSV infections.

Outcomes of severe lower respiratory tract infection in Mexican children with cancer

Abstract Background Lower respiratory tract infections (LRTI) are a very serious complication in children with cancer, with high morbidity and mortality, due to viral infections, followed by bacterial and fungal organisms. These patients with cancer are undergoing chemotherapy that damages their mucosal barrier and respiratory epithelium, and course with profound or severe neutropenia. Thus, they are high-risk to develop severe respiratory infections acquired from the community. However, the clinical characteristics, etiological agents, finding on computed tomography (CT) and outcomes of the LRTI in immunocompromised patients are not well known, these are necessary in order to start adequate management including empirical antimicrobial therapy and supplementary oxygen therapy. Methods Children with cancer who were attended in the pediatric emergency room due to fever (>38°C) and presence of respiratory symptoms such as increased breath rate, cough, O2Sat <93%, and needed to supplementary oxygen were included. To analyze the cases of children with cancer and LRTI we documented the data regarding to clinical presentation, detection of respiratory virus and findings in the CT. Data such age, sex, oncological diagnosis, absolute neutrophil count. The detection of nucleic acid of respiratory virus was performed by qPCR, whereas the identification galactomannan in serum was done for fungal diagnosis, and clinical presentation was initial used for diagnosis of bacterial LRTI. The findings on TC were included to integrate all the LRTI etiological diagnosis. The outcomes recorded were to need supplementary oxygen therapy (nasal cannula, high-flow nasal cannula or mechanical ventilation), ICU admission, and mortality on the follow for all patient included in the study. A descriptive statistical analysis was performed to estimate frequency of the etiological agents, outcomes, and mortality rate. Results A total of 10 children with cancer and severe LRTI were followed up, 60% female sex, age 5.5 years (range, 1-16 <); 80% had acute leukemias and 20% lymphoma. Seven (70%) children were diagnosed with bacterial LRTI, whereas two (20%) and one (10%) were viral LRTI-diagnosed. The finding in the CT were the follow: bilateral patchy consolidation and ill-defined small nodules for viral infection, centrilobular nodules and bronchial wall thickening for bacterial infection and scattered nodules or patchy focus for fungal infection. In respect to clinical presentation 90% had fever, 100% had cough, and 100% had O2Sat <93%. Of these patients 60% were presented with profound and 20% with severe neutropenia (p<0.05); 30% had required high-flow oxygen and 10% mechanical ventilation; and three (30%) patients required care in ICU. The mortality rate for severe LRTI was 30%. Conclusion Children with cancer and profound or severe neutropenia are in high-risk to develop severe LRTI and they have high mortality. The finding on the CT can help to start on adequate management for LRTI in immunosuppressed pediatric patients.

Proteomic profiling of the local and systemic immune response to pediatric respiratory viral infections.

We describe the first proteomic profiling of the lower airway and blood in critically ill children with severe viral lower respiratory tract infection (vLRTI). From tracheal aspirate (TA), we defined a proteomic signature of vLRTI characterized by increased expression of interferon signaling proteins and decreased expression of proteins involved in immune modulation including FABP and MIP-5. Using machine learning, we developed a parsimonious diagnostic classifier that distinguished vLRTI from non-infectious respiratory failure with high accuracy. Comparative analysis of paired TA and plasma specimens demonstrated limited concordance, although the interferon-stimulated protein ISG15 was significantly upregulated with vLRTI in both compartments. We further identified TSG-6 and CRP as airway biomarkers of bacterial-viral coinfection, and viral load analyses demonstrated positive correlation with interferon-related protein expression and negative correlation with the expression of neutrophil activation proteins. Taken together, our study provides new insight into the lower airway and systemic proteome of severe pediatric vLRTI.

ONCOLYTIC ACTIVITY OF HUMAN RESPIRATORY SYNCYTIAL VIRUS.

Oncolytic viruses (OVs) are emerging as novel tools in cancer therapy. Oncolytic virotherapy offers an attractive therapeutic combination of tumor-specific killing and immune co-stimulation, therefore amplifying the host immune response against tumors. Moreover, OVs can be engineered for the expression of different immunostimulatory molecules to optimize and enhance the efficacy of oncolytic virotherapy. The effectiveness of OVs has been demonstrated in many preclinical studies for different types of cancers to achieve the aim of personalized cancer therapy. Human respiratory syncytial virus (RSV), an RNA virus of the Pneumoviridae family causes severe lower respiratory tract infections in infants and immunocompromised individuals. Interestingly, the oncolytic activity of RSV demonstrated in human prostate, hepatocellular, and dermal cancer cells is mostly mediated via apoptotic cell death associated with the impaired NF-κB activation or with the defect of the IFNα/β-induced STAT-1 activation. At the same time, the studies on cervical cancer revealed that RSV infection resulted in autophagy activation and apoptosis through the ROS-BAX and TNF- α-mediated pathways. The rational combinations of OVs, including RSV, with other approaches may benefit patients whose response to conventional therapies is limited. Here, we discuss the oncolytic activity of RSV and its potential use against different types of cancer.

Impact of Respiratory Syncytial Virus and Severe Acute Respiratory Syndrome Coronavirus 2 Coinfection on Clinical Severity and Outcomes Among Children Hospitalized With Lower Respiratory Tract Infections in Soweto, South Africa

Background: No data are available regarding the interplay and clinical manifestations of respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) coinfection in African children. We compared clinical characteristics and outcomes between RSV-only, SARS-CoV-2–only and RSV/SARS-CoV-2 coinfection lower respiratory tract infections (LRTI) in hospitalized African children. Methods: Prospective surveillance of children (0–59 months) hospitalized with severe LRTI was undertaken between March 1, 2020, and March 31, 2023, in Johannesburg, South Africa. Nasopharyngeal swabs for respiratory viruses and clinical data were collected, and clinical characteristics and outcomes were described and compared. Respiratory index of severity in children (RISC) scores were calculated for HIV-uninfected children, and covariates associated with high RISC scores (≥5) were evaluated. Results: Seven thousand four hundred fifty-six children [6.1 months (interquartile range, 14.4–18.6); 57.7% male] were enrolled, 1372 (18.4%) testing RSV+/SARS-CoV-2– (RSV only), 223 (3.0%) RSV−/SARS-CoV-2+ (SARS-CoV-2–only) and 28 (0.4%) RSV+/SARS-CoV-2+ (RSV/SARS-CoV-2 coinfection). Children with RSV only and RSV/SARS-CoV-2 coinfection were more likely to present with bronchiolitis than those with SARS-CoV-2–only (673/1372 and 15/28 vs. 46/223; P < 0.001). Children with RSV/SARS-CoV-2 coinfection had more severe disease than those with RSV or SARS-CoV-2–only, as well as a higher RISC score than SARS-CoV-2–only. Weight-for-age Z scores [adjusted risk ratio (aRR): 0.92], room air saturations (aRR: 0.988) and RSV+ status (aRR: 1.40) were independently associated with severe disease. Conclusions: Although both RSV and SARS-CoV-2 LRTI occurred commonly, coinfection did not. Children with RSV/SARS-CoV-2 coinfection had a higher prevalence of severe LRTI than those with RSV or SARS-CoV-2–only. These findings reinforce the urgent need for safe and effective RSV and SARS-CoV-2 vaccines, especially in children in low- and middle-income countries, where the burden of disease is the highest and the access to medical resources the lowest.

Intracellular delivery of antiviral shRNA using penetratin-based complexes effectively inhibits respiratory syncytial virus replication and host cell apoptosis

BackgroundCell-penetrating peptides (CPPs) are effective for delivering therapeutic molecules with minimal toxicity. This study focuses on the use of penetratin, a well-characterized CPP, to deliver a DNA vector encoding short hairpin RNA (shRNA) targeting the respiratory syncytial virus (RSV) F gene into infected cells. RSV is known to cause severe lower respiratory infections in infants and poses significant risks to immunocompromised individuals and the elderly. We evaluated the antiviral efficacy of the penetratin-shRNA complex by comparing its ability to inhibit RSV replication and induce apoptosis with ribavirin treatment.MethodsPenetratin-shRNA complexes were prepared at different ratios and analyzed using gel retardation assays, dynamic light scattering, and zeta potential measurements. The complexes were tested in HEp-2 and A549 cells for transfection efficiency, cytotoxicity, viral load, and apoptosis using plaque assays, real-time reverse transcription-polymerase chain reaction (RT-PCR), DNA fragmentation, propidium iodide staining, and caspase 3/7 activation assays.ResultsThe gel shift assay determined that a 20:1 CPP-to-shRNA ratio was optimal for effective complexation, resulting in particles with a size of 164 nm and a zeta potential of 8.7 mV. Transfection efficiency in HEp-2 cells was highest at this ratio, reaching up to 93%. The penetratin-shRNA complex effectively silenced the RSV F gene, reduced viral titers, and decreased DNA fragmentation and apoptosis in infected cells.ConclusionPenetratin effectively delivers shRNA targeting the RSV F gene, significantly reducing viral load and preventing apoptosis without toxicity. This approach surpasses Lipofectamine and shows potential for future therapeutic interventions, especially when combined with ribavirin, against RSV infection.Graphical

Clinical and economic inpatient burden of respiratory syncytial virus (RSV) infections in children < 2 years of age in Germany, 2014-2019: a retrospective health claims analysis.

Respiratory syncytial virus (RSV) is a common cause for severe lower respiratory tract infections (LRTI) in children < 2 years of age in Germany - though little is known about the clinical and economic burden of RSV in children with and without risk factors per month of life. In a retrospective health claims analysis, we identified RSV inpatient cases between 2014 and 2019. We assessed incidence rates, mortality rate, healthcare resource utilization, associated direct costs per case and excess costs for 30, 90 and 365 days after hospital admission matched to a control group. The outcomes are reported separately for the first and second year of life (i.e., for infants and toddlers) and were stratified by month of life, preterm and risk status (i.e., presence of underlying disease: chronic respiratory or cardiac disease, immunosuppression, neurological diseases, diabetes, conditions originating in the perinatal period). RSV-attributable hospital incidence rate was higher in infants (30.25/1,000) than toddlers (14.52/1,000), highest in the first three months of life (44.21/1,000), in infants born preterm (64.76/1,000) or with any underlying disease (54.85/1,000). Mortality rate was also higher for infants (0.08/1,000) than toddlers (0.04/1,000). Mean 30-day excess costs ranged from 2,953 € for infants born full-term at no risk, hospitalized for 5 days, to 6,694 € for infants born extremely premature, hospitalized for 7 days. In Germany, the clinical and economic burden of RSV is substantial, especially in the most vulnerable population, that is, very young infants, those born premature and/or those with an underlying disease.

Comparison of characteristics of children hospitalized for respiratory syncytial virus infection during the pre- and post-COVID-19 eras: a multicenter retrospective study

BackgroundRespiratory syncytial virus (RSV), a leading cause of lower respiratory tract infection (LRTI) among children, has resurged in the form of endemic or even pandemic in many countries and areas after the easing of COVID-19 containment measures. This study aimed to investigate the differences in epidemiological and clinical characteristics of children hospitalized for RSV infection during pre- and post-COVID-19 eras in Yunnan, China.MethodsA total of 2553 pediatric RSV inpatients from eight hospitals in Yunnan were retrospectively enrolled in this study, including 1451 patients admitted in 2018–2019 (pre-COVID-19 group) and 1102 patients admitted in 2023 (post-COVID-19 group). According to the presence or absence of severe LRTI (SLRTI), patients in the pre- and post-COVID-19 groups were further divided into the respective severe or non-severe subgroups, thus analyzing the risk factors for RSV-associated SLRTI in the two eras. Demographic, epidemiological, clinical, and laboratory data of the patients were collected for the final analysis.ResultsA shift in the seasonal pattern of RSV activity was observed between the pre-and post-COVID-19 groups. The peak period of RSV hospitalizations in the pre-COVID-19 group was during January–April and October–December in both 2018 and 2019, whereas that in the post-COVID-19 group was from April to September in 2023. Older age, more frequent clinical manifestations (fever, acute otitis media, seizures), and elevated laboratory indicators [neutrophil-to-lymphocyte ratio (NLR), c-reactive protein (CRP), interleukin 6 (IL-6), co-infection rate] were identified in the post-COVID-19 group than those in the pre-COVID-19 group (all P < 0.05). Furthermore, compared to the pre-COVID-19 group, the post-COVID-19 group displayed higher rates of SLRTI and mechanical ventilation, with a longer length of hospital stay (all P < 0.05). Age, low birthweight, preterm birth, personal history of atopy, underlying condition, NLR, IL-6 were the shared independent risk factors for RSV-related SLRTI in both pre- and post-COVID-19 groups, whereas seizures and co-infection were independently associated with SLRTI only in the post-COVID-19 group.ConclusionsAn off-season RSV endemic was observed in Yunnan during the post-COVID-19 era, with changed clinical features and increased severity. Age, low birthweight, preterm birth, personal history of atopy, underlying condition, NLR, IL-6, seizures, and co-infection were the risk factors for RSV-related SLRTI in the post-COVID-19 era.

Poor stress resilience in adolescence predicts higher risk of severe COVID-19 and other respiratory infections: A prospective cohort study of 1.4 million Swedish men

ObjectivesTo investigate the associations between stress resilience in late adolescence and later risk of severe COVID-19 and other lower respiratory infections. A secondary aim was to examine potential confounding between low cardiorespiratory fitness (CRF) and stress resilience in relation to respiratory infection. MethodsWe conducted a registry-based cohort study of 1.4 million Swedish men, undergoing military conscription between 1968 and 2005. All were assessed by a psychologist for stress resilience, receiving a score between 1 and 9. The outcomes were hospitalization or death due to COVID-19 from March 2020 to September 2021 and hospitalization due to bacterial or viral pneumonia from conscription until January 2020. A secondary aim was to examine potential confounding between low cardiorespiratory fitness (CRF) and stress resilience in relation to respiratory infection. ResultsPoor stress resilience in late adolescence is associated with later risk of severe lower respiratory infections. Using a high resilience score as the reference, the hazard ratio (95 % CI) for death due to COVID-19 for the lowest scores was 1.49 (1.01–2.18) adjusted for CRF and other confounders. The corresponding adjusted hazard ratios for hospitalization due to bacterial pneumonia were 2.28 (2.03–2.57) and for viral pneumonia 1.92 (1.33–2.79). No significant interaction was seen between stress resilience and CRF in the analysis. ConclusionsPoor stress resilience is a prospective factor for severe COVID-19 as well as for bacterial and viral respiratory pneumonia endpoints, independent of CRF. These findings imply an effect of late adolescent stress resilience on the immune system later in life.

The Role of the CX3CR1-CX3CL1 Axis in Respiratory Syncytial Virus Infection and the Triggered Immune Response.

Respiratory syncytial virus (RSV) is a common respiratory pathogen that causes respiratory illnesses, ranging from mild symptoms to severe lower respiratory tract infections in infants and older adults. This virus is responsible for one-third of pneumonia deaths in the pediatric population; however, there are currently only a few effective vaccines. A better understanding of the RSV-host relationship at the molecular level may lead to a more effective management of RSV-related symptoms. The fractalkine (CX3CL1) receptor (CX3CR1) is a co-receptor for RSV expressed by airway epithelial cells and diverse immune cells. RSV G protein binds to the CX3CR1 receptor via a highly conserved amino acid motif (CX3C motif), which is also present in CX3CL1. The CX3CL1-CX3CR1 axis is involved in the activation and infiltration of immune cells into the infected lung. The presence of the RSV G protein alters the natural functions of the CX3CR1-CX3CL1 axis and modifies the host's immune response, an aspects that need to be considered in the development of an efficient vaccine and specific pharmacological treatment.

Influenza A (H1N1) in Hospitalized Children.

Influenza A (H1N1) is a contagious respiratory infection caused by the influenza A virus. In the majority of cases, H1N1 influenza is benign. However, it can be dangerous for infants and children with underlying chronic diseases. The severity of influenza depends on various factors, including the virulence of the virus strain, preexisting immunity level, and individual health conditions. The aim of this study is to describe the clinical profile of H1N1 influenza in hospitalized infants and children. This is a prospective and descriptive study conducted from November 1, 2018, to January 31, 2024. In this study, we included all children under 14 years old hospitalized for suspected severe lower respiratory infection who had gone through virological testing. We used a multiplex polymerase chain reaction (PCR) kit: the Film Array-Respiratory Panel. Due to the depletion of multiplex PCR kits, this study continued using rapid influenza diagnostic tests based on immunochromatographic technique. We report 45 confirmed cases of H1N1 influenza, collected during the period from November 1, 2018, to January 31, 2024. The average age was 2 years and 4 months. The main reason for admission was respiratory distress found in all patients. In 53% of the cases, there was an associated comorbidity, including asthma (17 cases), prematurity (2 cases), congenital adrenal hyperplasia (2 cases), cystic fibrosis (1 case), undetermined etiology bronchial dilation (1 case), and Basedow's disease (1 case). The clinical presentation included viral bronchiolitis (17 cases), moderate asthma exacerbation (10 cases), severe asthma exacerbation (7 cases), pneumonia (9 cases), bronchial dilation exacerbation (1 case), and flu-like syndrome with adrenal insufficiency (1 case). Fever was present in 31 patients. Gastrointestinal symptoms such as diarrhea and vomiting were present in 20 cases. Three patients required intensive care, with 2 children being intubated and ventilated (one severe acute asthma and one severe viral bronchiolitis). Two cases were treated with oseltamivir. The average length of hospital stay was 7.5 days, ranging from 3 to 20 days. All cases showed favorable evolution. We conclude that preventive measures remain crucial, and influenza vaccination is highly recommended in cases of underlying morbidity.

Economic burden of respiratory syncytial virus in adults in Germany – a health claims analysis between 2015 and 2018

Aims Respiratory syncytial virus (RSV) causes severe lower respiratory tract infections (LRTI) in infants and adults. While the clinical burden was recently estimated in adults in Germany, little is known about the economic burden. To fill this gap, this study aimed to assess hospital and outpatient healthcare resource utilization (HRU) and costs of RSV infections in adults in Germany. Methods In this retrospective, observational study on nationwide, representative, anonymized claims data (2015–2018), we identified patients ≥18 years with ICD-10-GM-codes specific to RSV (“RSV-specific”). To increase sensitivity, patients with unspecified LRTIs (including unspecified bronchitis, bronchiolitis, bronchopneumonia, and pneumonia) during RSV seasons were also included as cases potentially caused by RSV (“RSV-possible”). RSV-related HRU (hospital days, ICU and ventilation treatment, drug dispensation) and direct costs were estimated per episode. Excess costs per episode and for follow-up periods were compared to a matched control cohort. All outcomes were reported per healthcare sector and stratified by age and risk groups as well as disease severity (ICU admission/ventilation). Results Direct inpatient and outpatient mean episode costs were 3,473€ and 82€, respectively, with substantially higher costs for severe cases requiring intensive care and/or ventilation (10,801€). Direct costs for RSV-specific cases were higher than for RSV-possible cases (inpatients: 6,247€ vs. 3,450€; outpatients: 127€ vs. 82€). Moreover, costs were significantly higher for RSV patients than for controls and increased over time (inpatients: 5,140€ per episode vs 10,093€ per year; outpatients: 46€ per quarter vs 114€ per year). Limitations While the number of RSV-specific cases was low, inclusion of seasonal LRTI cases likely increased the sensitivity to detect RSV cases and allowed a better estimation of the total costs of RSV. Conclusions The economic burden of RSV-LRTI in adults in Germany is substantial, persists long-term, and is particularly high in the elderly. This highlights the need for cost-effective prevention measures.

Exposure to bacterial PAMPs before RSV infection exacerbates innate inflammation and disease via IL-1α and TNF-α

Respiratory syncytial virus (RSV) can cause severe lower respiratory tract infections. Understanding why some individuals get more serious disease may help with diagnosis and treatment. One possible risk factor underlying severe disease is bacterial exposure before RSV infection. Bacterial exposure has been associated with increased respiratory viral-induced disease severity but the mechanism remains unknown. Respiratory bacterial infections or exposure to their pathogen associated molecular patterns (PAMPs) trigger innate immune inflammation, characterised by neutrophil and inflammatory monocyte recruitment and the production of inflammatory cytokines. We hypothesise that these changes to the lung environment alter the immune response and disease severity during subsequent RSV infection. To test this, we intranasally exposed mice to LPS, LTA or Acinetobacter baumannii (an airway bacterial pathogen) before RSV infection and observed an early induction of disease, measured by weight loss, at days 1–3 after infection. Neutrophils or inflammatory monocytes were not responsible for driving this exacerbated weight loss. Instead, exacerbated disease was associated with increased IL-1α and TNF-α, which orchestrated the recruitment of innate immune cells into the lung. This study shows that exposure to bacterial PAMPs prior to RSV infection increases the expression of IL-1α and TNF-α, which dysregulate the immune response resulting in exacerbated disease.

Pediatric COVID-19 in Lesotho and Post-pandemic Implications on Lower Respiratory Infections in Children.

Background The United States Agency for International Development (USAID) Reaching Impact, Saturation, and Epidemic Control (RISE) program funded Jhpiego to support the Government of Lesotho's COVID-19 response, including two national COVID-19 treatment centers. To evaluate the status of post-pandemic pediatric respiratory care in Lesotho, we analyzed pediatric treatment center data and healthcare worker (HCW) performance on pediatric COVID-19 training offered to HCWs at COVID-19 treatment centers. Methods We conducted a retrospective cohort study of patients 15 years of age or less hospitalized at two COVID-19 treatment centers in Lesotho from May 1, 2020, to April 30, 2022. Patient data were extracted from hospital files. We used the independent sample t-test, Mann-Whitney U test, or Fisher's exact test to evaluate associations between exposure variables and death. We also assessed differences between pre- and post-training examination scores of three one-day HCW training on pediatric COVID-19 using paired t-tests. Results Overall, <15-year-olds comprised 18/1,448 (1.2%) hospitalizations. Twenty-two percent (4/18) of children were hypoxemic (oxyhemoglobin saturation <94%) within the first 24 hours and 44% (8/18) at any point in the hospitalization. Oxygen utilization increased over the two-year period (p=0.004) and all eight children with hypoxemia received oxygen (p<0.001). Four of 18 (22%) patients died. For HCW training, pre- and post-training examinations were completed by 76/82 (92.7%) participants. The overall mean pretraining score was 44.6% (standard deviation (SD) 15.7%). Mean scores improved by an average of 32.2% (95% confidence interval (CI) 27.7%, 36.6%, p<0.001) on the same day post-training examination. Conclusions National COVID-19 treatment center data indicate a low burden of severe pediatric COVID-19 disease in Lesotho. However, recognized HCW knowledge gaps suggest deficiencies in identifying and referring severely ill children, which may detrimentally impact the ongoing post-pandemic care of children with severe lower respiratory infections.

Impact of respiratory syncytial virus on older children: Exploring the potential for preventive strategies beyond the age of 2 years

ObjectiveRespiratory syncytial virus (RSV) causes significant lower respiratory tract infections (LRTIs) in infants and young children. Current prevention targets those under 2 years. This study aims to evaluate RSV patterns and severity in children older than 2 years and to explore the potential extension of preventive strategies to this demographic group. MethodsAn observational retrospective study at Meyer Children’s Hospital (from October 2019 to March 2023) analyzed data from patients between 28 days and 18 years of age with RSV infection. Severity indicators and patient characteristics were compared between two age groups: under 2 years and 2 years and above. Results584 infants and young children were hospitalized due to RSV infection. Epidemic seasons saw a rise in hospitalizations among children older than 2 years. Older children had higher comorbidity (41% versus 9% p=0.000) and prematurity (26% versus 14% p = 0.001) rates than those under 2 years. ConclusionThe study highlights the increased risk of severe RSV LRTIs in children older than 2 years and with prematurity or comorbidities, overlooked by current preventive measures. Prospective studies and cost-effectiveness analyses are needed to determine the necessity of targeted immunization for older children with specific risk factors, aiming to reduce RSV-related morbidity and mortality.

A novel combined nomogram for predicting severe acute lower respiratory tract infection in children hospitalized for RSV infection during the post-COVID-19 period.

Off-season upsurge of respiratory syncytial virus (RSV) infection with changed characteristics and heightened clinical severity during the post-COVID-19 era are raising serious concerns. This study aimed to develop and validate a nomogram for predicting the risk of severe acute lower respiratory tract infection (SALRTI) in children hospitalized for RSV infection during the post-COVID-19 era using machine learning techniques. A multicenter retrospective study was performed in nine tertiary hospitals in Yunnan, China, enrolling children hospitalized for RSV infection at seven of the nine participating hospitals during January-December 2023 into the development dataset. Thirty-nine variables covering demographic, clinical, and laboratory characteristics were collected. Primary screening and dimension reduction of data were performed using Least Absolute Shrinkage and Selection Operator (LASSO) regression, followed by identification of independent risk factors for RSV-associated SALRTI using Logistic regression, thus finally establishing a predictive nomogram model. Performance of the nomogram was internally evaluated by receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) based on the development dataset. External validation of our model was conducted using same methods based on two independent RSV cohorts comprising pediatric RSV inpatients from another two participating hospitals between January-March 2024. The development dataset included 1102 patients, 239 (21.7%) of whom developed SALRTI; while the external validation dataset included 249 patients (142 in Lincang subset and 107 in Dali subset), 58 (23.3%) of whom were diagnosed as SALRTI. Nine variables, including age, preterm birth, underlying condition, seizures, neutrophil-lymphocyte ratio (NLR), interleukin-6 (IL-6), lactate dehydrogenase (LDH), D-dimer, and co-infection, were eventually confirmed as the independent risk factors of RSV-associated SALRTI. A predictive nomogram was established via integrating these nine predictors. In both internal and external validations, ROC curves indicated that the nomogram had satisfactory discrimination ability, calibration curves demonstrated good agreement between the nomogram-predicted and observed probabilities of outcome, and DCA showed that the nomogram possessed favorable clinical application potential. A novel nomogram combining several common clinical and inflammatory indicators was successfully developed to predict RSV-associated SALRTI. Good performance and clinical effectiveness of this model were confirmed by internal and external validations.

PD1+CD4+ T cells promote receptor editing and suppress autoreactivity of CD19+CD21low B cells within the lower respiratory airways in adenovirus pneumonia

Human adenovirus (HAdV) pneumonia poses a major health burden for young children, however, factors that contribute to disease severity remain elusive. We analyzed immune cells from bronchoalveolar lavage (BAL) of children with HAdV pneumonia and found that CD19+CD21low B cells were significantly enriched in the BAL and were associated with increased autoantibody concentrations and disease severity. Myeloid cells, PD-1+CD4+ T helper cells and CD21low B cells formed tertiary lymphoid structures within the respiratory tracts. Myeloid cells promoted autoantibody production by expressing high amounts of B cell activating factor (BAFF). In contrast, PD-1+CD4+ T helper cells induced production of IgG1 and IgG3 antibodies but suppressed autoreactive IgGs by initiating B cell receptor editing. In summary, this study reveals cellular components involved in protective versus autoreactive immune pathways in the respiratory tract, and these findings provide potential therapeutic targets for severe HAdV lower respiratory tract infections.

Acute cough in outpatients: what causes it, how long does it last, and how severe is it for different viruses and bacteria?

ObjectivesTo describe the symptoms, duration, severity, and microbiology of lower respiratory tract infection (LRTI) in outpatients. MethodsProspective cohort study of adults in US primary or urgent care with a chief complaint of cough and symptoms consistent with LRTI. Baseline data included demographics, signs, symptoms, and PCR for 46 viruses and bacteria. The severity of symptoms reported for ≤28 days follow-up via diary and text message. The Bronchitis severity score assessed severity at baseline; overall severity was defined as the area under the symptom severity curve. ResultsOf 718 patients with complete baseline data, 618 had valid PCR results, and 443 were followed until symptoms resolved. Of those with valid PCR, 100 (16.2%) had 1+ viruses detected, 211 (34.1%) had 1+ bacteria, and 168 (27.2%) had both. Symptoms more likely with viral or mixed infection included feverishness (36.7–38.4% vs. 18.5%), chills or sweats (36.0–38.1% vs. 17.9%), being generally unwell (78.2–81.3% vs. 64.9%), and myalgias (42.7–48.2% vs. 28.6%). Coloured sputum (42.9% vs. 23.2–29.5%) was more common with a bacterial infection. The mean duration of cough was 14.7 days with viruses (95% CI: 13.2–16.2), 17.3 with bacteria (95% CI: 15.9–18.6), 16.9 with mixed infection (95% CI: 15.2–18.6), and 18.4 with no detection (95% CI: 16.1–20.8). Overall severity of cough was lower for viral infections (20.9 points, 95% CI: 18.6–23.3) than for other groups (range 24.2–26.3). The most common potential bacterial pathogens were Haemophilus influenza (28.0%), Moraxella catarrhalis (16.2%), and Streptococcus pneumoniae (10.2%), whereas the most common viral pathogens were rhinovirus (17.3%), influenza (12.8%), SARS-CoV-2 (11.5%), and seasonal coronaviruses (8.1%). DiscussionThe mean duration of cough was 16.4 days. Consistent with European studies, the type of infection or potential pathogen was not an important predictor of the duration or severity of LRTI.

SARS-CoV-2 antigenemia and RNAemia in association with disease severity in patients with COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, causes a spectrum of symptoms ranging from mild upper to severe lower respiratory tract infections. However, the dynamics of nucleocapsid (N) protein antigenemia and RNAemia are not fully understood. We conducted a cohort study involving 117 patients with clinically confirmed COVID-19, focusing on the kinetics of antigenemia and RNAemia and their association with various clinical characteristics. The patients had a median age of 66.0 years (52.0–79.0 years), with a gender distribution of 46.2% male and 53.8% female. Antigenemia reached 100% in fatal cases during the first week after admission. The sensitivity/specificity of antigenemia for diagnosis were 64.7%/73.0% at admission, 69.1%/100% in Week 1, and 66.3%/100% in Week 2. Additionally, the rates of antigenemia in asymptomatic patients were 27.3% upon admission and 22.0% in Week 1, respectively; however, no antigenemia was in samples collected in Week 2. Viral RNAemia was not detected in asymptomatic patients, but RNAemia viral loads were elevated in fatal cases. Kaplan–Meier survival curves demonstrated a higher mortality rate when antigenemia concentrations were elevated in the follow-up samples (P = 0.005). Our study provides a comprehensive analysis of the kinetics of viral N-protein antigenemia and RNAemia according to disease severity and clinical classification. Our findings suggest that highest concentrations of antigenemia in fatal cases occur in the first week after admission, indicating that early elevated antigenemia may serve as a marker of mortality risk.