Introduction Viral infections are associated with pulmonary exacerbations in children with Cystic Fibrosis (cwCF), but after 3 years of SARS-CoV-2 pandemic, whether cwCF are at higher risk of developing COVID-19 or its adverse consequences remains controversial. Methods We conducted an observational, multicenter, cross-sectional study of cwCF infected by SARS-CoV-2 between March 2020 and June 2022, (1 st to 6 th COVID-19 pandemic waves) in Spain. The study aimed to describe patients’ basal characteristics, SARS-CoV-2 clinical manifestations and outcomes, and whether there were differences across the pandemic waves. Results During study time, 351 SARS-CoV2 infections were reported among 341 cwCF. Median age was 8.5 years (range 0-17) and 51% were female. Cases were unevenly distributed across the pandemic, with most cases (82%) clustered between November 2021 and June 2022 (6 th wave, also known as Omicron Wave due to the higher prevalence of this strain in that period in Spain). Most cwCF were asymptomatic (24.8%) or presented with mild Covid-19 symptoms (72.9%). Among symptomatic, most prevalent symptoms were fever (62%) and increased cough (53%). No multisystem inflammatory syndrome (MIS-C), persisting symptoms, long-term sequelae or deaths were reported. Conclusions Spanish current data indicate that cwCF do not experience higher risks of SARS-CoV-2 infection nor worse health outcomes or sequelae. Changes in patients’ basal characteristics, clinical courses and outcomes were detected across waves. While the pandemic continues, and new SARS-CoV-2 variants are being identified, a worldwide monitoring of COVID-19 in pediatric CF patients is needed.

The receptor for advanced glycation end products (RAGE) has been studied in several respiratory diseases described as an important inflammatory mediator. The RAGE-axis is activated by multiple endogenous ligands related to pro-inflammatory states, upregulate the RAGE expression. The function of soluble RAGE (sRAGE) is not completely understood, it has been hypothesized an anti-inflamatory role as RAGE decoy receptor. Few studies have explored the RAGE-axis in Cystic Fibrosis (CF) with contradictory results. Based on previously, we present this pilot study with the aim of describe the plasma sRAGE levels in children with cystic CF (CFp), compare with the sRAGE levels in a healthy cohort and study its possible correlation with CFp clinical features. We conducted a single-center, cross-sectional observational study. We included 35 clinically stable CF patients (aged < 18 years). The median plasma sRAGE level in CFp was 1494,75 pg/ml [interquartile range (IQR) 708,75pg/ml], compared with 714,20 pg/ml (IQR 490,50 pg/ml)) in the historical cohort of healthy controls (p < 0,001). A positive correlation was found between plasma sRAGE level and forced expiratory volume in 1 second/forced vital capacity ratio (FEV1/FVC) (p 0,004) and forced expiratory flow between 25% and 75% (FEF25%-75%) (p 0,032). In this preliminary study, the plasma sRAGE level were higher in CFp than in healthy controls. Also, we described a positive correlation between FEV1/FVC and FEF25%-75% and plasma sRAGE. To our knowledge, our study is the largest to describe plasma sRAGE values ​​in CFp and the only one carried out in pediatric CF population.