Background Nirsevimab, a novel monoclonal antibody, provides passive immunity against RSV-infections in infants. In October/2023, Spain adopted immunization for children <6 months and those born during the epidemic season. Our main goal was to compare clinical, epidemiological and virological characteristics of respiratory infections in hospitalized infants before and after nirsevimab introduction. Methods. A prospective study was conducted in two Madrid hospitals during the 2022-23 and 2023-24 epidemic seasons. Infants <12 months admitted with lower respiratory tract infections were included. Clinical, epidemiological, and virological characteristics were compared based on admission before or after nirsevimab introduction and whether they received it. Results A total of 717 infants were included: 526 before October/2023 and 191 thereafter. Admissions from October-March 2023/24 decreased by 59% (95%CI:58.7-62.3%) compared to October-March 2022/23. ICU admissions dropped by 74% (95%CI:70.7-77.3%). Of those hospitalized after October/2023, 55(28.8%) received nirsevimab, with 11(20%) contracting RSV. The RSV-detection rate was lower after October/2023 (39% vs. 65%, P<0.001), as was the detection of other respiratory viruses, except rhinovirus and human bocavirus. Patients admitted after October/2023 were older (P=0.002), included fewer infants under 1 month (P=0.005), and had shorter hospital stays (P=0.001). For infants under 3 months, the likelihood of needing a stay > 5 days was 70% lower compared to those admitted before October/2023 (P<0.001;OR:0.39, 95%CI:0.22-0.66). Conclusions Nirsevimab has shown considerable effectiveness in shielding young infants from severe outcomes linked to RSV-infection. Furthermore, our study observed a notable decrease in hospitalizations for infections caused by other respiratory viruses after the introduction of nirsevimab.

The prevalence of asthma in children in Europe is an average of 10.3%. The role of asthma as a risk factor for COVID-19 in children is unknown. Our aim was to study the prevalence of asthma in children with SARS-CoV-2 infection and to compare them in hospitalized children and those with mild ambulatory symptoms. We conducted an observational retrospective study in 99 children (between 3- 17 years of age) with a confirmed SARS-CoV-2 infection between March and December 2020. The existence of a history of asthma was investigated using the validated ISAAC questionnaire and clinical data on COVID-19 were compiled. The median age was 10 years (IQR=13-5), and 60/99 (60.6%) patients had mild infections controlled as outpatient, while 39/99 (39.4%) required admission. The prevalence of asthma ─affirmative response to question 6 of the ISAAC questionnaire─ was 11.1% (11/99). The prevalence of asthma in children who required admission increased to 17.9% and to 21.4% in patients requiring PICU, while in outpatients children was 6.7% (p=0.079). We found a significant association between the use of salbutamol during the last year and the need for admission (23.1% in hospitalized patients vs 3.3% in outpatients; OR= 8.7, 95%CI 1.7-42.8). Likewise, budesonide treatment in the last year (17.9% vs 1.7%, OR= 12.9, 95%CI 1.5-109.5) was also a risk factor for admission. Therefore, a history of asthma was not a risk factor for SARS-CoV-2 infection in our series, but active asthma could be a risk factor for severity and need for hospitalization for COVID-19 in children

Background: Respiratory viral infections (RVIs) are frequent in preterm infants and may have long-term impact on respiratory morbidity, especially those with bronchopulmonary dysplasia (BDP). The immune response and respiratory are key defence elements, so the purpose of this study is to evaluate the immune response regulation and the respiratory epithelial barrier integrity in the preterm infants suffering RVIs during Neonatal Intensive Care Unit (NICU) admission. Materials and methods: Nasopharyngeal aspirate (NPA) was obtained, separating cells from supernatants. Viral detection was performed by RT-nested PCR, and gene expression by qPCR. Proteins were detected by western blot and ELISA or Luminex. Small airway epithelial cells (SAEC) were stimulated with Poly:IC and/or wounds. Results: Pre-infection samples from 26 preterm infants that later developed RVIs had less frequency of filaggrin gene expression and fewer protein levels compared to 23 noninfected controls. Conversely, filaggrin, IL-1β, MIP-1β, VEGF and HIF-1α levels were higher in pre-infection supernatant samples, being infection-risk biomarkers. IL-17A, RANTES, VEGF, and HIF-1α levels were higher during and post infection, while MCP-1 and amphiregulin were reduced after infection. Small airway epithelial cells (SAEC) stimulated by poly:IC reduced filaggrin gene expression and increased its levels at supernatant. Finally, poly:IC stimulation over SAEC increased TLR3 and TSLP expression, while reduced AREG. Conclusion: Filaggrin gene expression and protein quantity was reduced at cellular level of the NPA, while its secreted levels were increased in basal samples from infected newborns and in SAEC stimulated with poly:IC. Our findings highlight the importance of filaggrin as a factor facilitating RVIs.

Objective Long-term respiratory consequences of bronchopulmonary dysplasia (BPD) in preterm infants born in the post-surfactant era (“new” BPD) remain partially unknown. The present study aimed to evaluate respiratory outcomes of “new” BPD in adolescents who were born preterm. Methods This multicenter, cross-sectional study included 286 adolescents born between 2003 and 2005 (mean age: 14.2 years); among them, 184 and 102 were born extremely preterm (EP) (< 28 weeks’ gestation) and moderate-late preterm (32 to < 37 weeks’ gestation), respectively. Among EP adolescents, 92 had BPD, and 92 did not. All participants underwent lung function tests, skin prick testing, and questionnaires on asthma symptoms and quality of life. Results EP adolescents with BPD had significantly lower forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, and forced expiratory flow between 25%–75% of FVC than other included adolescents. FEV1/FVC ratios were below the lower limit of normal (z-score < −1.645) in 30.4% of EP adolescents with BPD, 13.0% of EP adolescents without BPD, and 11.8% of adolescents who were born moderate-late preterm. Bronchodilator response and air-trapping were significantly higher in BPD adolescents than in other adolescents. Diffusion capacity was significantly lower in EP adolescents than in moderate-late preterm adolescents. Asthma symptoms and quality of life scores were similar among groups. Conclusion EP adolescents with “new” BPD had poorer pulmonary function than EP adolescents without BPD or moderate-late preterm adolescents. Further studies are needed to determine whether “new” BPD is associated with early-onset chronic obstructive pulmonary disease in adulthood.