To study the clinical impact of respiratory viral infection in children with cystic fibrosis (CF).

Retrospective cohort study.

Tertiary care referral centre for CF in India.

Children with CF attending a pediatric chest clinic.

Case records of the children with CF who had a pulmonary exacerbation with documented acute respiratory viral infection between October 2013 and December 2014 (Group I) and an equal number of controls (Group II) with pulmonary exacerbation in absence of acute respiratory viral infection were reviewed.

The two groups were compared for the following outcomes over a period of 12–18 months: bacterial colonization, antibiotics usage, pulmonary exacerbations, numbers of outpatient visits, hospitalization and oxygen therapy and spirometric parameters.

In total, 46 children [23 each with viral infection (Group I) and without viral infection (Group II)] of age 7–264 months were enrolled; baseline clinical status and pulmonary function tests were comparable. Mean (SD) follow-up duration in those who had viral infection and who had no viral infection was 15.7 (7.1) and 17.5 (5.4) months, respectively. On follow-up, children with viral infection (Group I) had adverse outcome in form of greater worsening of Shwachman clinical scores, number of pulmonary exacerbations requiring antibiotic usage [4 (2.1%)] and [2.8 (1.7%)], need for intravenous antibiotics 30.4% vs. 8.7%, hospitalization rates 31.8% vs. 4.3% and mortality 30.4% vs. 4.7%, respectively.

Acute viral infection in children with CF affected course of illness on follow-up, including frequent and severe pulmonary exacerbations requiring hospitalization, intravenous antibiotics, decline in CF scores and increased mortality over next 12–18 months.