Concentrations of nitrogen compounds are related to severe rhinovirus infection in infants. A time-series analysis from the reference area of a pediatric university hospital in Barcelona

Background: There is scarce information focused on the effect of weather conditions and air pollution on specific acute viral respiratory infections, such as rhinovirus (RV), with a wide clinical spectrum of severity. Objective: The aim of this study was to analyze the association between episodes of severe respiratory tract infection by RV and air pollutant concentrations (NOx and SO2 ) in the reference area of a pediatric university hospital. Methods: An analysis of temporal series of daily values of NOx and SO2 , weather variables, circulating pollen and mold spores, and daily number of admissions in the pediatric intensive care unit (PICU) with severe respiratory RV infection (RVi) in children between 6 months and 18 years was performed. Lagged variables for 0-5 days were considered. The study spanned from 2010 to 2018. Patients with comorbidities were excluded. Results: One hundred and fifty patients were admitted to the PICU. Median age was 19 months old (interquartile range [IQR]: 11-47). No relationship between RV-PICU admissions and temperature, relative humidity, cumulative rainfall, or wind speed was found. Several logistic regression models with one pollutant and two pollutants were constructed but the best model was that which included average daily NOx concentrations. Average daily NOx concentrations were related with the presence of PICU admissions 3 days later (odds ratio per IQR-unit increase: 1.64, 95% confidence interval: 1.20-2.25)). Conclusions: This study has shown a positive correlation between NOx concentrations at Lag 3 and children's PICU admissions with severe RV respiratory infection. Air pollutant data should be taken into consideration when we try to understand the severity of RVis.This project was partially supported by the Spanish National Health Institute Carlos III (Grant id. PI17/349). Desiree Henares received a grant for predoctoral training in research into Health by the Spanish National Health Institute Carlos III (project number: FI17/00248). The funders have not influenced the design or analysis, nor have they had any role inpreparing the manuscript.S

Lower Respiratory Tract Infection and Genus Enterovirus in Children Requiring Intensive Care: Clinical Manifestations and Impact of Viral Co-Infections

Infection by rhinovirus (RV) and enterovirus (EV) in children ranges from asymptomatic infection to severe lower respiratory tract infection (LRTI). This cohort study evaluates the clinical impact of RV/EV species, alone or in codetection with other viruses, in young children with severe LRTI. Seventy-one patients aged less than 5 years and admitted to the Paediatric Intensive Care Unit (PICU) of a reference children's hospital with RV or EV (RV/EV) LRTI were prospectively included from 1/2018 to 3/2020. A commercial PCR assay for multiple respiratory pathogens was performed in respiratory specimens. In 22/71, RV/EV + respiratory syncytial virus (RSV) was found, and 18/71 had RV/EV + multiple viral detections. Patients with single RV/EV detection required invasive mechanical ventilation (IMV) as frequently as those with RSV codetection, whereas none of those with multiple viral codetections required IMV. Species were determined in 60 samples, 58 being RV. No EV-A, EV-C, or EV-D68 were detected. RV-B and EV-B were only found in patients with other respiratory virus codetections. There were not any associations between RV/EV species and severity outcomes. To conclude, RV/EV detection alone was observed in young children with severe disease, while multiple viral codetections may result in reduced clinical severity. Differences in pathogenicity between RV and EV species could not be drawn.This project is supported by the Spanish National Health Institute Carlos III (Grant id. PI17/349). DH received a grant for predoctoral training in research into Health by the Spanish National Health Institute Carlos III (project number: FI17/00248). DH also received a grant from Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica (SEIMC) for a research stay. The funders have not influenced the design or analysis, nor have they had any role in preparing the manuscript.S

Bronchiolitis, epidemiological changes during the SARS-CoV-2 pandemic

Background: Bronchiolitis is the most common viral infection of the lower respiratory tract in infants under 2 years of age. The aim of this study was to analyze and compare the seasonal bronchiolitis peaks before and during the SARS-CoV-2 pandemic. Methods: Descriptive, prospective, and observational study. Patients with severe bronchiolitis admitted to the Pediatric Intensive Care Unit (PICU) of a referral tertiary hospital between September 2010 and June 2021 were included. Demographic data were collected. Viral laboratory-confirmation was carried out. Each season was analyzed and compared. The daily average temperature was collected. Results: 1116 patients were recruited, 58.2% of them males. The median age was 49 days. Respiratory syncytial virus (RSV) was isolated in 782 cases (70.1%). In April 2021, the first and only case of bronchiolitis caused by SARS-CoV-2 was identified. The pre- and post-pandemic periods were compared. There were statistically significant differences regarding: age, 47 vs. 73 days (p = 0.006), PICU and hospital length of stay (p = 0.024 and p = 0.001, respectively), and etiology (p = 0.031). The peak for bronchiolitis in 2020 was non-existent before week 52. A delayed peak was seen around week 26/2021. The mean temperature during the epidemic peak was 10ºC for the years of the last decade and is 23ºC for the present season. Conclusion: The COVID-19 pandemic outbreak has led to a clearly observable epidemiological change regarding acute bronchiolitis, which should be studied in detail. The influence of the environmental temperature does not seem to determine the viral circulation