SARS-CoV-2-related bronchiolitis: a multicentre international study

Background: Bronchiolitis is the main acute lower respiratory tract infection in infants. Data regarding SARS-CoV-2-related bronchiolitis are limited. Objective: To describe the main clinical characteristics of infants with SARS-CoV-2-related bronchiolitis in comparison with infants with bronchiolitis associated with other viruses. Setting, patients, interventions: A multicentre retrospective study was conducted in 22 paediatric emergency departments (PED) in Europe and Israel. Infants diagnosed with bronchiolitis, who had a test for SARS-CoV-2 and were kept in clinical observation in the PED or admitted to hospital from 1 May 2021 to 28 February 2022 were considered eligible for participation. Demographic and clinical data, diagnostic tests, treatments and outcomes were collected. Main outcome measures: The main outcome was the need for respiratory support in infants testing positive for SARS-CoV-2 compared with infants testing negative. Results: 2004 infants with bronchiolitis were enrolled. Of these, 95 (4.7%) tested positive for SARS-CoV-2. Median age, gender, weight, history of prematurity and presence of comorbidities did not differ between the SARS-CoV-2-positive and SARS-CoV-2-negative infants. Human metapneumovirus and respiratory syncytial virus were the viruses most frequently detected in the group of infants negative for SARS-CoV-2.Infants testing positive for SARS-CoV-2 received oxygen supplementation less frequently compared with SARS-CoV-2-negative patients, 37 (39%) vs 1076 (56.4%), p=0.001, OR 0.49 (95% CI 0.32 to 0.75). They received less ventilatory support: 12 (12.6%) high flow nasal cannulae vs 468 (24.5%), p=0.01; 1 (1.0%) continuous positive airway pressure vs 125 (6.6%), p=0.03, OR 0.48 (95% CI 0.27 to 0.85). Conclusions: SARS-CoV-2 rarely causes bronchiolitis in infants. SARS-CoV-2-related bronchiolitis mostly has a mild clinical course.