Introduction
The current coronavirus-induced disease 2019 (COVID-19) pandemic due to
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection
is a major burden for the global healthcare infrastructure. Several
comorbidities such as diabetes, hypertension, coronary heart disease,
obesity and metabolic syndrome confer an increased the risk for
SARS-CoV-2 infection and/or severe COVID-19, including
COVID-19-associated mortality . In contrast to seasonal influenza, an
early cohort reported that the prevalence of asthma among COVID-19
patients in the Tongji Hospital (Wuhan) was 0.9%, lower than that in
the adult population of Wuhan (6.4%) . We previously published on the
global epidemiology of asthma among COVID-19 patients and found striking
geographic differences defining high (eg USA, UK, Ireland and Australia)
and low (eg China, Italy, Spain, Israel, Mexico, Brazil, Saudi Arabia,
India) asthma COVID-19 zones . However, why these differences were
observed was unclear.
Individuals with asthma are more susceptible to respiratory viral
infections and the majority of acute asthma exacerbations are preceded
by a common cold, which is attributed to rhinoviruses, influenza and
respiratory syncytial virus (RSV) among other viruses . Furthermore,
asthma has been consistently recognized as a major risk factor for
influenza-associated hospitalization across several seasons reviewed in
. In regards to COVID-19 infections, data indicate that SARS-CoV-2
infection is not associated with acute asthma exacerbations but the
relationship between asthma and severe COVID-19 outcomes is less clear.
Early onset asthma is associated with a lower risk of SARS-CoV-2
positive PCR test . Some studies suggest that non-allergic asthma is
associated with a greater risk for severe COVID-19 as compared to
individuals with allergic/type 2 asthma . Indeed, there is evidence that
type 2 mediator IL-13 inhibits SARS-CoV-2 infection of bronchial
epithelium and
that asthma medication such as inhaled corticosteroids protect from
worsening COVID-19 symptoms. Inhaled corticosteroids presumably reduce
the expression of angiotensin converting enzyme-2 (ACE-2) and
transmembrane protease serine in the lung . Currently, there is no
indication that children with asthma are at higher risk for (severe)
COVID-19 than children without asthma .
There is little information on the interrelationship between COVID-19
and chronic inflammatory airway disorders studied by international sites
using validated and unified criteria. Such reports often correct for age
and sex but very rarely adjust for existing comorbidities, which can
vary greatly throughout the world. In this context, the objective of our
study was to compare asthma prevalence among hospitalized COVID-19
patients in major global hubs across continents as well as associated
clinical and laboratory features.