Respiratory viruses were frequently detected in young children with cystic fibrosis but had limited clinical significance.

Aim: Knowledge about the clinical role that respiratory viruses play in infants and toddlers with cystic fibrosis (CF) remains limited. We determined the prevalence of respiratory viruses in routine respiratory secretion samples in children aged 0-3 years with CF. Associations with bacterial infections, respiratory tract symptoms and lung function were also explored.

Methods: This prospective, longitudinal, single-centre study added viral polymerase chain reaction detection to the routine monitoring of CF lung disease at Copenhagen University Hospital, Denmark, from 1 July 2019 to 31 August 2020. The existing programme included monthly clinical assessments with endo-laryngeal suction for bacterial culturing and quarterly lung function testing.

Results: We studied 19 children (11 males) with a median age of 1.8 (range 0.11-2.99) years. Viruses were detected in 86/193 (45%) samples. Rhinoviruses and enteroviruses were the most common (88%), followed by adenoviruses (9%), parainfluenza 1-3 (6%) and the respiratory syncytial virus (5%). A positive association was found between the annual incidence of viruses and bacteria, but there was no correlation with respiratory tract symptoms or lung function.

Conclusions: Respiratory viruses were commonly detected in routine respiratory secretion samples. However, the results from this small study did not justify specific conclusions.