4 Discussion
The current systematic review provides a quantitative estimate of the
asthma control of the current ongoing COVID-19 pandemic in children. The
COVID-19 outbreak and the measures taken to it have had significant
influences on asthma control among children. We have shown for the first
time that the level of asthma control was significantly improved during
the COVID-19 pandemic compared to the same period before it, with a
reduction of asthma exacerbation, asthma admission and emergency room
visit. One reason of these results is probably associated with the
lockdown measures during COVID-19 pandemic, which limit viral disease
transmissions, reduce the possible exposure to asthma triggers, such as
viral infections, outdoor allergens, physical activities, and air
pollution21-23. It might also be explained by
caregivers’ afraid to bring children to hospital because of the risk of
exposure to SARS‐Co-V224. And increased treatment
adherence is also an important factor. Caregivers are afraid of going to
hospital in the special time, so they pay more attention to their health
than that before the pandemic and treat their children’s asthma in time,
and take the treatment actively, thus the times of visits to the
hospital has decreased and the frequency of asthma exacerbation has also
decreased. Anyway, these results mean less medication and healthcare
resources are used in the control of children’s asthma.
The outcome of use of inhaled corticosteroids and Beta-2 agonists shows
no significant difference. In fact, on one hand, a lot of children
reduced their maintenance therapy (use of inhaled corticosteroids and
Beta-2 agonists), it is likely because of the good level of disease
control, in the study of Ullmann et al.18 showed the
significant reduction of respiratory symptoms, which meant there was a
real improvement in asthma control. On the other hand, there are some
children stepped up their therapy during the lockdown. It was not only
because of symptoms or the fear and anxiety related to the spreading of
the COVID‐19 pandemic25-27. Also, studies have
suggested that inhaled corticosteroids may enhance innate immunity to
viral infections28,29, reduce susceptibility to severe
respiratory viral infections and can downregulate virus
angiotensin-converting enzyme-2 receptor expression in the airways in
the case of SARS-CoV-230.
The outcome of c-ACT scores were not analyzed, though many articles
included it. It was mainly because of the different manifestations used.
For example, Papadopoulos et al.17 use number of
people to show improved scores. Jia et al.16 use the
number of people whose scores were greater or equal to 20 which means
good control. Ullmann et al.18 use the exact scores
directly. Yucel et al.19 use the ratio of score less
than 20. So it is hard to unite these outcomes. This is a problem that
needs to be unified in the follow-up studies.
Although the current meta-analysis results show that the control of
asthma in children has been improved during pandemic, we are still
concerned about the question that will childhood asthma worsen if the
lockdown continues for a very long time? The asthma control of patients
with indoor allergen sensitization might be worse. Confounding factors
such as increased exposure to indoor allergens, such as HDMs, molds, pet
allergens, and decreased exposure to seasonal outdoor allergens such as
pollens may have both negative and positive effects respectively on
asthma. Further researches are needed.
After the COVID-19 disappearing, children suffering from asthma and
their caregivers should still reduce exposure to asthma triggers like
viral infections, outdoor allergens, and air pollution, at the same time
increase treatment adherence, just do what they underwent in the
pandemic, thus to restore, maintain and promote effective asthma
management for children, this is the meaning of our writing this
article.
Our review has several limitations. First, the sample size of this
meta-analysis was relatively small. As a result, the unknown risk of
bias caused by incomplete data could constrain our results. Second, our
results are based on observational studies, which are susceptible to
design bias, selection bias and residual confounding. Third, in this
study was that heterogeneity across the studies was substantial, which
could be attributed to different definition of severity used or sample
size. Despite these limitations, this meta-analysis provides information
on the association between children’s asthma control and COVID-19
pandemic.