Abstract
Background: Bronchiolitis is inflammation of the bronchioles usually due to acute viral infection, primarily respiratory syncytial virus (RSV). This study aims to quantify the current burden of bronchiolitis that might be ameliorated by recent advances in RSV prevention (e.g., maternal RSV vaccine, immunoprophylaxis).
Methods: We calculated incidence per 1,000 of hospitalisations coded as acute bronchiolitis in the National Minimum Dataset from 2000 to 2022 by age (0–11, 12–23, and 24–35 months), prioritised ethnicity (Māori, Pacific, and non-Māori non-Pacific [NMNP]), and deprivation quintile (1–5) of residence.
Results: Bronchiolitis accounted for 60% of respiratory hospitalisations under 12 months, with incidence of 74.8, 95% CI [73.8, 75.8], 5 times higher than 12–23 months (15.2, 95% CI [14.8, 15.7]), declining to 0.9, 95% CI [0.8, 1.1], at 2–3 years. Overall incidence of bronchiolitis (0–35 months) increased between 2000 (23.6, 95% CI [22.9, 24.3]) and 2019 (35.4, 95% CI [34.6, 36.3]). In 2020, incidence declined by more than 70% related to public health measures during the COVID-19 pandemic but returned to pre-pandemic levels in 2021 following brief border opening limited to Australia. Compared with NMNP children, the incidence rate ratio (IRR) for bronchiolitis was 3.0, 95% CI [2.9, 3.1], among tamariki Māori and 3.9, 95% CI [3.8, 4.0], among Pacific children. The IRR for bronchiolitis among children living in the most (compared to the least) deprived quintile was 2.8, 95% CI [2.7, 2.9].
Conclusion: Families living in areas of high deprivation have less access to warm, dry, uncrowded homes and higher exposure to tobacco smoke and air pollution, likely driving the disparities in hospitalisations for bronchiolitis. Measures to improve living environments, and access to RSV prevention through maternal vaccination or immunoprophylaxis, are urgently needed to reduce the high and inequitable burden of severe bronchiolitis in Aotearoa.