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.

There is a high inter-rater reliability, showing the BROSJOD score to be reliable and valid, even when different observers apply it. Pediatr Pulmonol. 2017;52:533-539. © 2016 Wiley Periodicals, Inc.

Bronchiolitis is an acute inflammatory injury of the bronchioles, which is usually caused by a viral infection. It is the most common cause of lower respiratory tract infection in the first year of life. 1-3 Respiratory syncytial virus is the most common causative agent. 4,5 An important complication is the concurrence of an invasive bacterial infection and these include pneumonia, meningitis, sepsis and urinary tract infections. Invasive bacterial infections are a major cause of morbidity and mortality, with a considerable prevalence in infants who require paediatric intensive care unit (PICU) admission and mechanical ventilation. 6-8 One of the main challenges is making a differential diagnosis between invasive bacterial infections and isolated viral infections, especially in younger patients with bronchiolitis. Consequently, it is common to use antibiotics for severe cases of bronchiolitis. However, often this is not necessary, because in most cases it is a viral illness. 9,10

NIV seems to be a safe and feasible technique during pediatric ground transport. Careful patient selection, adequate material, and a well-trained transport team are crucial to minimize risks to the patient.

The objective was to evaluate the use of procalcitonin (PCT) and C-reactive protein (CRP) for the diagnosis of bacterial infection in bronchiolitis patients. A prospective, single-centre, descriptive, and comparative observational study was carried out on patients with severe bronchiolitis admitted to the paediatric intensive care unit (PICU), from January 2011 to July 2017. Two cohorts were compared: patients with invasive bacterial infection (IBI) and patients with no bacterial infection (NBI). We included 675 patients, 399 of whom were males (59.1%), with median age of 47 days (IQR 25-100.3). Of them, 181 patients were diagnosed with IBI (26.8%). Seventytwo had sepsis (10.7%), 106 had pneumonia (15.7%), and 41 had a urinary tract infection (6.1%). PCT and CRP values were significantly higher in patients with IBI. ROC curves compared the ability of PCT and CRP to diagnose IBI at admission, 24 h, and 48 h. PCT showed a better AUC for diagnosing IBI, with statistically significant differences at all time points (p < 0.001). The best PCT cut-off for IBI diagnosis at admission was 1.4 ng/mL, with a sensitivity of 69% (95% CI 58.4-74.9) and a specificity of 91% (95% CI 88.1-92.5). Procalcitonin showed a better AUC for diagnosing both sepsis and pneumonia, which makes it an excellent predictor. Conclusion:We present PCT as a novel test in comparison with the traditional CRP screening test to discern which bronchiolitis patients have IBI. We highlight the importance of PCT for the diagnosis of pneumonia and sepsis, as it proved to be more sensitive and specific than CRP, with statistically significant differences. What is Known:• Bronchiolitis should be treated with antibiotics only when a bacterial infection is present.• The rate of antibiotic prescription in severe bronchiolitis is extremely high, so diagnostic tools are needed. What is New:• PCT is a good biomarker to discern which bronchiolitis patients have IBI, specially for pneumonia and sepsis diagnoses. It is more sensitive and specific than CRP, with statistically significant differences. • Implementation of PCT cut-off values may prevent unnecessary antibiotic use.