The authors declare no conflicts of interest. The authors would like to thank all Brazilian pediatric intensivists that have been strenuously devoted to the study and care of critically-ill children, especially those affected by acute respiratory failure. “
“Acute viral bronchiolitis (AVB) caused by respiratory syncytial virus (RSV) is the primary infection of the lower airways

in children under 2 years of age worldwide, and it is the main cause of hospitalization in this age group in developed countries.1 Although all children are infected with RSV by the age of three, most infections are mild and have no sequelae. The mechanisms involved with the severity of AVB caused by RSV are not yet fully understood. Why does RSV infection present Ipatasertib cost such variable evolution in different patients? Why does one child with RSV remain asymptomatic and another child dies? When assessing the severity of AVB caused by RSV, which factors are more often associated: genetic and/or epidemiological/environmental factors? These questions have intrigued researchers and remain without definitive answers. There are 3,000 to 4,000 deaths annually

in the United States due to AVB caused by RSV.2 The prevalence of hospitalization due to RSV in the United States is 48.9 per 1,000 in children younger than 3 months, 26 per 1,000 in those younger than 1 year, Epigenetics Compound Library and 1.8 per 1,000 in children aged 1 to 5 years, with 132,000 to 172,000 hospitalizations/year due to

RSV in children under 5 years.3 In the United States, there are, on average, 22.8 visits to the emergency room caused by RSV per 1,000 infants; 29% of whom are Oxymatrine hospitalized. That represents an annual spending of 50.5 million dollars on emergency room visits and 650 million dollars on hospitalizations.4 In other regions, the rate of hospitalization per 1,000 infants with RSV varies from 8.7 in Australia5 to 60 in Japan.6 In Australia, the incidence of RSV is from 110.0 to 226.5 per 1,000 infants, and the annual cost is estimated at $ 50 million dollars, which is more significant than the costs of Influenza and Rotavirus infections. 5 In Europe, RSV is responsible for 45% of hospitalizations for lower respiratory infection in children younger than 2 years. 6 In Brazil, a study of 5,304 children younger than 1 year showed that 113 (2.1%) were hospitalized due to AVB.7 Among the children hospitalized for RSV, 2.7% were admitted to the intensive care unit (ICU), 1.5% required assisted ventilation, and 0.2% died.8 Infection by RSV has variable severity with clinical manifestations from mild symptoms in the upper respiratory tract to bronchiolitis and pneumonia, and may develop into the severe form, requiring ICU admission and mechanical ventilation, and at times leading to death. To date, the treatment of AVB by RSV is supportive. It has been demonstrated that, in the United States, of 1.