Respiratory syncytial virus: viral load, viral decay, and disease progression in children with bronchiolitis.

Acute viral bronchiolitis is the major cause of hospital admissions in children under 2 years of age, and respiratory syncytial virus (RSV) can be responsible for up to 80% of these infections. We aimed to describe RSV dynamics among hospitalized children with bronchiolitis. Upper respiratory samples of 101 hospitalized patients were collected and submitted to RSV detection by a quantitative real-time RT-PCR to assess viral load (Log RNA copies/mL). Seventy-two patients were positive for RSV infection, of which 38 (52.7%) could be followed up until RSV was no longer detected. The first RSV RT-qPCR was carried out on average on the 5th day of symptom onset. Thirty-six patients (94.7%) were still shedding RSV after 7 days, and 9 (23.6%) after 14 days of symptoms onset. Only 2 patients (5.2%) were still shedding RSV after 21 days. Only 7 of the followed patients (18.9%) were submitted to intubation. There was no difference between the viral load of the first collected sample and the viral persistence of patients with comorbidities, who needed intensive care unit and who needed intubation. These data could help understand RSV dynamics and future studies and treatments to come.