Discussion
Our study describes relatively mild and limited respiratory consequences
of COVID-19 in our group of children. There are several results from our
research. First, we found a relatively low risk of structural and/or
functional abnormalities of the respiratory tract and clinical remission
usually occurred within several months.
Second, we recognized four subgroups of respiratory post-COVID syndrome
with different symptomatology in the studied cohort. Besides the
standard post-COVID group, “sporty” subgroup was represented by
children used to high-intensity physical activities. These subjects
sensitively identified worsening in their physical performance, and
their results were usually normal. This group is very probably
under-reported due to observer bias. Children with no regular sports
activity could miss discrete symptoms exertional dyspnea without regular
physical activity. The third subgroup denotes probable incipient
bronchial asthma. COVID-19 is not a potential trigger but may coincide
with this frequent chronic diagnosis. Furthermore, the focused attention
of parents on respiratory symptoms in children after COVID-19 may
accelerate early examination by a pulmonologist. There was usually
positive family history, atopic history, positive allergy panel, and an
excellent response to anti-asthma treatment. This group could be
over-reported due to detection bias by pulmonologists. The fourth
subgroup includes „polymorphous” post-COVID with a wide variety of
symptoms (headache, concentration deficiency, anxiety, hair loss, chest
pain, cough, dyspnea, anxiety, tachycardia) which were noticed apart
from the monitored respiratory symptoms. Adolescent girls highly
predominate. Previous mental health problem in them or their close
relatives was found in 60%. This group reflects the complex
consequences of COVID-19 pandemic in a very fragile age. In our study
this group is very probably under-reported due to selection bias.
Variety of their non respiratory problems may lead to referral to
another specialist and not to a pulmonologist.
Our results are in accordance with other published work designed as case
series. These studies confirmed existence of pediatric post-COVID
syndrome and reported diverse symptoms and infrequent occurrence. The
first paper on post-COVID-19 syndrome was published by Ludgvisson et al.
in November 2020. They collected data from parental reports of five
Swedish children with persistent symptoms lasting two months or more
after acute COVID infection. Parents contacted authors on an
Internet-based social media forum. These children’s symptoms lasted for
6-8 months after their clinical diagnoses of COVID-19 and included
fatigue, dyspnea, cardiac palpitations, chest pain, headache, muscle
weakness, dizziness, and sore throat. Subsequently, Buonsenso et al.
published a cross-sectional study in which 129 children aged 6–16 years
diagnosed with COVID-19 between March and November 2020 were interviewed
by phone or in an outpatient clinic.
More than one-third reported one or two lingering symptoms four months
or more after COVID-19 infection, and a further one-quarter had three or
more symptoms. Insomnia, fatigue, muscle pain, and persistent cold-like
complaints were common. In a prospective cohort study of Monteni et al.,
about 1.8% of 1379 children experienced symptoms for at least 56 days
after acute COVID, according to data reported by adult proxy via mobile
application Radtke et al. compared in a longitudinal cohort study the
occurrence of at least one symptom lasting beyond 12 weeks in
seropositive and seronegative children (4% vs 2%). Parents reported
symptoms via an online questionnaire. The most common complaints
included fatigue, difficulty concentrating, and increased sleepiness.
Brackel et al. conducted a Dutch national survey on 89 children with
long COVID identified by pediatric departments. The most frequent
symptoms comprised fatigue, dyspnea, and concentration difficulties;
authors described in detail a case series of six children.
To our knowledge, our work is a first prospectively planned study
focused on respiratory aspects of pediatric post-COVID. Our data suggest
lower risk of functional lung impairment compared to published data in
adults.
The strength of our study includes the cooperation of centers collecting
data from all regions of the Czech Republic and timing of the survey
following a peak of the critical epidemic situation in the Czech
Republic with highest COVID-19 related mortality worldwide. Actual
evidence of 1.67 million confirmed SARS infections as of August 2021 may
assure adequately large sample for monitoring pediatric post-COVID.
The main limitations comprise differences in laboratory equipment and
software between centers, and a rather short follow-up to allow for
timely publishing of the results.