Impact of the Covid-19 Pandemic on the Prevalence of Wheeze In Children in Hong Kong

Background
During the COVID-19 pandemic, children in Hong Kong experienced a zero-COVID policy, prolonged school closure and a mandatory maskwearing requirement. They had significantly less exposure to microbes and represented a more naïve immune system. We explored the prevalence of wheeze in previously healthy children in Hong Kong during the pandemic. We postulated that the reduced viral load of other respiratory viruses during this time would affect their immune response and predispose them to allergic diseases, such as asthma.
Methods
Children admitted for the first episode of wheeze from January 2017 to December 2022 were included. They were divided into pre-COVID and during COVID, spanning from January 2017 to December 2019 and January 2020 to December 2022 respectively. Patients older than 18 years old, with a history of asthma or a known anatomic abnormality causing chronic bronchial obstruction were excluded. Patient demographics including age on admission, respiratory virus identified, duration of hospital stay, the need for oxygen, respiratory support and intensive care unit [ICU] admission were collected.
Results
During the pandemic, there was a 38.4% decrease in hospitalization for wheeze, with 190 admissions pre-COVID compared to 117 admissions during COVID. The children requiring admission during COVID were younger, with mean age of 3.0 ± 2.5 years compared to 4.0 ± 2.9 years pre-COVID [p = 0.002]. They also had more severe disease, with a higher prevalence of children requiring oxygen [p = 0.025] and ICU admission [p = 0.001].
Conclusion
We explored the prevalence of wheeze in healthy children during COVID and found that hospitalisation was decreased compared to pre-COVID. Those hospitalised during COVID had more severe disease. We postulate that this paediatric population could represent a specific “post-COVID” phenotype. Longitudinal studies focusing on the prevalence of asthma in this cohort is needed.

Keywords:Wheeze; Asthma; COVID-19

Abbreviations:COVID-19: coronavirus disease 2019
WHO: World Health Organisation
ACE2: angiotensin-converting enzyme 2
ICU: intensive care unit
HHHFNC: heated humidified high-flow nasal cannula
NIV: non-invasive ventilation