2.1 Data Source
We searched PubMed, Embase, and Cochrane Library for the update articles
published from the inception of each database to Jun 1, 2021. when
duplicate publications were identified, we chose the most complete and
recent trial . Two investigators (Z.Y. and X.W.) independently retrieved
all the related studies in the databases and excluded duplicate
publications. The combined text and medical subject heading (MeSH) terms
were cross-searched using MeSH and free word as follows: (
Asthma[Mesh] OR allergic asthma[Title/Abstract] OR Bronchial
Asthma[Title/Abstract]) AND Control[Title/Abstract]) AND
(COVID-19[Mesh] OR COVID-19 Virus Disease[Title/Abstract] OR
COVID-19 Virus Infection[Title/Abstract] OR 2019-nCoV
Infection[Title/Abstract] OR Coronavirus
Disease-19[Title/Abstract] OR 2019 Novel Coronavirus
Disease[Title/Abstract] OR 2019-nCoV Disease[Title/Abstract] OR
SARS Coronavirus 2 Infection[Title/Abstract] OR SARS-CoV-2
Infection[Title/Abstract] OR (COVID-19 Pandemic[Title/Abstract])
AND (Child[Mesh] OR Children[Title/Abstract]). We also reviewed
abstracts and presentations from major conference proceedings up to Jun
1, 2021 to ensure that no additional studies were overlooked.