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\begin{document}

\title{The lung ultrasound in children with SARS-COV 2 infection: a national
multicenter prospective study}



\author[1]{Maria Supino}%
\author[2]{Danilo Buonsenso}%
\author[3]{Rino Agostiniani}%
\author[4]{Laura Gori}%
\author[5]{Vincenzo Tipo}%
\author[2]{Rosa Morello}%
\author[6]{Angelo Giovanni Delmonaco}%
\author[7]{Raffaele Falsaperla}%
\author[8]{Carlotta  Biagi}%
\author[9]{Salvatore Cazzato}%
\author[1]{Alberto Villani}%
\author[1]{Anna Maria Musolino}%
\author[1]{Simona Scateni}%
\author[1]{Valentina Ferro}%
\author[1]{Barbara Scialanga}%
\author[1]{Alessia Mesturino}%
\author[1]{Elena Boccuzzi}%
\author[5]{Carolina D'Anna}%
\author[9]{Vittorio Romagnoli}%
\author[7]{Silvia Marino}%
\author[3]{Roberta Puxeddu}%
\author[9]{Gaia Martelli}%
\author[5]{Thaililja Gagliardo}%
\author[1]{Manuel Murciano}%
\author[10]{Federica Pellizzoni}%
\affil[1]{Ospedale Pediatrico Bambino Gesu}%
\affil[2]{Policlinico Universitario Agostino Gemelli Dipartimento Scienze della Salute della Donna e del Bambino}%
\affil[3]{Azienda USL Toscana centro Sede di Pistoia}%
\affil[4]{Ospedale Santa Chiara}%
\affil[5]{Azienda Ospedaliera di Rilievo Nazionale Santobono Pausilipon}%
\affil[6]{Azienda Ospedaliero Universitaria Citta della Salute e della Scienza di Torino}%
\affil[7]{Azienda Sanitaria Provinciale di Catania}%
\affil[8]{Azienda Ospedaliero Universitaria Ospedali Riuniti di Ancona Umberto I G M Lancisi G Salesi}%
\affil[9]{IRCCS Azienda Ospedaliero-Universitaria di Bologna}%
\affil[10]{Universita Vita Salute San Raffaele}%


\vspace{-1em}



  
  \date{May 28, 2024}


\begingroup
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\selectlanguage{english}
\begin{abstract}
Covid-19 causedhospitalizations, severe disease and deaths in any age,
including in the youngest children. The aim of this multicenter national
study is to characterize the clinical and the prognostic role of lung
ultrasound (LUS) in children with Covid-19. We enrolled children between
1 month and 18 years of age diagnosed with SARS-CoV2 infection and
whounderwenta lung ultrasound within 6 hours from firstmedical
evaluation. A total of 213 children were enrolled, 51.6\%were male,
median age was2 years and 5 months (IQR 4mm- 11 yearsand4 months).One
hundred and fortyeight (69.4\%) children were admitted in hospital, 9
(6.1\%) in pediatric intensive care unit.We found an inverse correlation
between the LUS score and the oxygen saturationatthe clinical evaluation
(r = -0.16; p = 0.019). Moreover, LUS scores were significantly higher
in patients requiring oxygen supplementation (8 (IQR 3 - 19) vs 2 (IQR 0
- 4); p= 0.001). Among LUS pathological findings, irregular pleural
line, sub-pleural consolidations and pleural effusions were
significantly more frequentin patients whoneeded oxygen supplementation
(p = 0.007; p = 0.006 andp = 0.001, respectively). This multicentric
study confirmed that LUS is able to detect Covid-19 low respiratory
tract involvement, which is characterized by pleural line
irregularities, vertical artifacts and subpleural consolidations.
Notably, children with higher LUS score have an higher risk of
hospitalization or need for oxygen supplementation, supporting LUS as a
valid and safe point-of-care first level tool for the clinical
evaluation of children with Covid-19.%
\end{abstract}%



\sloppy


TITLE PAGE

The lung ultrasound in children with SARS-COV 2 infection: a national
multicenter prospective study

Maria Chiara Supino\textsuperscript{1*}, MD, Danilo
Buonsenso\textsuperscript{2,3}, MD, PhD, Rino
Agostiniani\textsuperscript{4}, MD, Laura Gori\textsuperscript{5}, MD,
Vincenzo Tipo\textsuperscript{6}, MD, Rosa Morello\textsuperscript{2},
MD, Giovanni Del Monaco\textsuperscript{7}, MD, Raffaele
Falsaperla\textsuperscript{8}, MD, Carlotta Biagi\textsuperscript{9},
MD, Salvatore Cazzato\textsuperscript{10}, MD, Alberto
Villani\textsuperscript{1}, MD, PhD, Anna Maria
Musolino\textsuperscript{1}, MD and the PLUSCOVID-19 Study Group

PLUSCOVID-19 Study group: Pediatric Lung UltraSoundCOrona Virus Disease
19

Simona Scateni\textsuperscript{1}, MD, Valentina
Ferro\textsuperscript{1}, MD, Barbara Scialanga\textsuperscript{1}, MD,
Maria Alessia Mesturino\textsuperscript{1}, MD, Elena
Boccuzzi\textsuperscript{1}, MD, Carolina D'Anna\textsuperscript{6}, MD,
Vittorio Romagnoli\textsuperscript{10}, MD, Silvia
Marino\textsuperscript{11}, MD, Roberta Puxeddu\textsuperscript{4}, MD,
Gaia Martelli\textsuperscript{10}, MD, Thaililja
Gagliardo\textsuperscript{6} , MD, Manuel Murciano\textsuperscript{1},
MD, Federica Pellizzoni\textsuperscript{12}, MD

Affiliations:

1 Pediatric Emergency Unit, Department of Emergency and General
Pediatrics, Bambino Ges\selectlanguage{ngerman}ù Children's Hospital, IRCCS, Rome, Italy.

2 Department of Woman and Child Health and Public Health, Fondazione
Policlinico Universitario A. Gemelli IRCCS, Rome Italy.

3 Centro di Salute Globale, Università Cattolica del Sacro Cuore, Roma,
Italy.

4 Department of Pediatrics, San Jacopo Hospital, Pistoia, Italy.

5 Department of Maternal and Child Health, Division of Pediatric Unit,
S. Chiara Hospital, Pisa, Italy.

6 Pediatric Emergency and Short Stay Unit, Santobono-Pausilipon
Children's Hospital, Naples, Italy.

7 Pediatric Emergency Unit, City of Health and Science of Turin, Turin,
Italy.

8 Neonatal Intensive Care Unit {[}NICU{]}, AOU ''Rodolico-San Marco'',
PO ''San Marco'', University of Catania, Catania, Italy.

9 Pediatric Unit, Department of Mother and Child Health, Salesi
Children's Hospital, Ancona, Italy.

10 Pediatric Emergency Unit, IRCCS Azienda Ospedaliero-Universitaria di
Bologna, Bologna, Italy.

11 Pediatric and Pediatric Emergency Department, AOUP ``Rodolico San
Marco'', PO ``San Marco'', University of Catania, Catania

12 Pediatric and Neonatal Unit, San Raffaele Hospital, Università
Vita-Salute San Raffaele, Milano

Keywords: pediatric, thorax, infection disease, emergency,pulmonary
ultrasound

\textbf{Conflict of interests} : the authors declare that there are no
conflicts of interests.

\textbf{Funding} : This work was supported also by the Italian Ministry
of Health with ''Current Research funds''

\textbf{Data availability statement:} the data that support the findings
of this study are available from the corresponding author upon
reasonable request.

\textbf{* Correspondence:} Maria Chiara Supino, MD

ORCID: https://orcid.org/0000-0003-2507-8886

Pediatric Emergency Unit

Department of Emergency and General Pediatrics

Bambino Gesù Children's Hospital, IRCCS

Piazza Sant'Onofrio 4, Rome, Italy.

Tel: +39 0668592909

E-mail:\emph{mariachiarasupino@gmail.com}

Running title:The lung ultrasound in children with SARS-COV 2 ABSTRACT

Covid-19 causedhospitalizations, severe disease and deaths in any age,
including in the youngest children. The aim of this multicenter national
study is to characterize the clinical and the prognostic role of lung
ultrasound (LUS) in children with Covid-19.

We enrolled children between 1 month and 18 years of age diagnosed with
SARS-CoV2 infection and whounderwenta lung ultrasound within 6 hours
from firstmedical evaluation.

A total of 213 children were enrolled, 51.6\%were male, median age was2
years and 5 months (IQR 4mm- 11 yearsand4 months).One hundred and
fortyeight (69.4\%) children were admitted in hospital, 9 (6.1\%) in
pediatric intensive care unit.We found an inverse correlation between
the LUS score and the oxygen saturationatthe clinical evaluation (r =
\selectlanguage{english}-0.16; p = 0.019). Moreover, LUS scores were significantly higher in
patients requiring oxygen supplementation (8 (IQR 3 - 19) vs 2 (IQR 0 -
4); p= 0.001).

Among LUS pathological findings, irregular pleural line, sub-pleural
consolidations and pleural effusions were significantly more frequentin
patients whoneeded oxygen supplementation (p = 0.007; p = 0.006 andp =
0.001, respectively).

This multicentric study confirmed that LUS is able to detect Covid-19
low respiratory tract involvement, which is characterized by pleural
line irregularities, vertical artifacts and subpleural consolidations.
Notably, children with higher LUS score have an higher risk of
hospitalization or need for oxygen supplementation, supporting LUS as a
valid and safe point-of-care first level tool for the clinical
evaluation of children with Covid-19.

\textbf{INTRODUCTION}

More than two years after the description of the first Covid-19 cases,
our understanding of the clinical impact of SARS-CoV-2 on child health
is significantly improved. Overall, Covid-19 has caused much higher
morbidity and mortality on adults compared with children, although
hospitalizations, severe disease and deaths have been recorded in any
age, including in the youngest children.\textsuperscript{1,2} Moreover,
children have also suffered from post-acute complications of SARS-CoV-2
infection, including the Multisystem Inflammatory Syndrome and Long
Covid.\textsuperscript{3-6}

The recognition that the large majority of children infected with
SARS-CoV-2 develop only mild symptoms and spontaneously completely
recover poses the challenge to understand the optimal way to
specifically evaluateinfected children, rather than simply translating
adult practice into pediatrics. For example, symptomatic adults assessed
in the emergency department (ED) frequently undergo laboratory
diagnostics and imaging, including chest X-Ray or Computed
Tomography.\textsuperscript{7} This approach was usually routine
practice in the pre-vaccine era, when the clinical impact of Covid-19 on
adults has been massive, and is now mostly reserved to symptomatic
patients. In children, such an approach does not seem justified. As most
children have a low risk of develop severe disease and vaccinations
further reduce this risk, an approach based on routine traditional
imaging does not seem justified, as it is associated with radiation
exposure and longer waiting times in the pediatric emergency department
(PED).\textsuperscript{1}

In this context, an approach based on safe and rapid point-of-care tools
to evaluate a child with SARS-CoV-2 infection seems to be more
appropriate. As Covid-19 pneumonia mainly affects the peripheral areas
of the lungs, early preliminary studies in both adults and children have
documented that Lung Ultrasound (LUS) can easily detect low respiratory
tract infection (LRTI) during SARS-CoV-2.\textsuperscript{8} However,
while several adult studies on large cohorts have documented also a
prognostic role of LUS in predicting hospitalizations and severe
outcomes in infected adults, pediatric studies have provided less
conclusive information, as they mostly included a small number of
patients from single centers and without enough patients with
moderate/severe disease. \textsuperscript{9-18}For these reasons, we
performed this multicenter national study in order to better
characterize the clinical and prognostic role of LUS in children with
Covid-19 assessed in the PED.

\textbf{MATERIALS ANDMETHODS}

\textbf{Study design and population}

This national multicenterprospective study was conducted between 15st
November 2020 and 30st June 2021 in 8italian hospitals (Bambino
GesuChildren Hospital of Rome, A. Gemelli University Polyclinic
Foundation of Rome, Santobono-Pausilipon Children's Hospital of Naples,
Sant'Orsola Hospital of Bologna, San Jacopo Hospital of Pistoia,Salesi
Children's Hospital of Ancona,San Marco Hospital of Catania,City of
Health and Science of Turin). After the initial approval by theethics
committee of the Bambino Gesu Children Hospital (2293\_OPBG\_2020), all
participating sites obtained approval from their local ethics
committee.Written informed consent to participate in this study was
provided by the children' legal guardian/next of kin.

We included children with more than 1 month and less than 18 years,
withdiagnosis of SARS-CoV2 infection made using molecular o antigenic
tests on a nasopharyngeal swab. In all enrolled patients a lung
ultrasound was performedwithin 6 hours from the initial medical
evaluation. Were excluded patients outside our age range, who refused to
participate, severe conditions requiring immediate life-saving
procedures, cardiac abnormalities, previous major thoracic surgery,
congenital pulmonary malformations, serious malformations of the rib
cage, cystic fibrosis, neuromuscular diseases or bronchopulmonary
dysplasia.

\textbf{Lung ultrasound}

LUS was performed using an ultrasound machine with a linear probe
(10mHzmedian frequency) with a unique focus on the pleural line and a
depth of 5 cm. The acquisitions were achieved by physicians having at
least one year experience in pediatric LUS.Images and clips were stored
and archived.

As suggested by Soldati et aleach hemithorax was divided in 7 areas:3
posterior (superior, inferior and paravertebral), 2 lateral (superior
and inferior) and 2 anterior(superior and inferior).\textsuperscript{19}

We evaluated the presence of pleural irregularities, subpleural
consolidations, B-lines and pleural effusions. The lung pattern was
classified in: score 0---normal sliding, a regular pleural line and
A-lines with fewer than 2 B-lines; score 1---a pleural line indented
with multiple well-defined B-lines; score 2---a broken pleural line
associated with dark areas and consolidation areas; score 3---large and
multiple patches of white lung. To investigate lung fields the patients
were positioned in sitting position. Therefore, we summarized the lung
ultrasound score in each area.

\textbf{Data collection and statistical analysis}

Data were collected through a RedCap (Research Electronic Data Capture)
program. Each site was identified with a number and the data of
individual patients were entered anonymously.The clinical report form
collected data on: gender, age, vital signs, diagnostic test performed
at arrived (blood sample, chest X-ray, CT scan), signs orsymptoms (e.g.
fever, diarrhea, chest pain, dyspnea),type of oxygen therapy during
hospitalization and disposition (discharge, admission to ward, pediatric
intensive care unit).The LUS report form collected data on
presence/absence of short vertical artifacts, isolated or multiple B
lines, white lung, consolidation \textless{} 1 cm or \textgreater{}1 cm,
thickening of the pleural line, pleural effusion.Statistical analysis
was performed using the SPSS software (IBM SPSS Statistics, version
24.0, Chicago, IL, USA).We tested the normality by
Kolmogorov-Smirnovtest. The continuous variables were reported as the
mean +- standard deviation (SD) or the median and interquartile range
(IQR), as appropriate. Frequencies and percentages (\%) were used to
describe categorical variables.The Mann--Whitney test andStudent'sttest
were used to compare nonparametric and normaldata, respectively, while
Pearson's \selectlanguage{greek}χ\selectlanguage{english}2 test or a Fisher's exact test were used, as appropriate. A
p-valueinferior0.05 wasconsideredstatisticallysignificant.

\textbf{RESULTS}

\textbf{Study population}

Two hundred and thirteen patients whit SARS-CoV2 infectionwere
enrolledbetween 15st November 2020 and 30st June 2021. One hundred and
ten (51.6\%) patients were male witha median age of 2 years and 5 months
(IQR 4mm- 11 yyand4 mm). Eighty-seven (40.9\%) children had less than 1
years of age, of whom 63 (29.6\%) had less than 6 months of age. At
medical history 160 (75.1\%) children presented fever at home, 67
(31.5\%)had respiratory symptoms, 75 (35.2\%) reported a reductionoffood
intake and 106 (49.8\%) indicated anepidemiological link. Fifteen (7\%)
children had chest pain, 8 (3.7\%) had anosmia and 6 (2.8\%) had
ageusia. At clinical evaluation the mean oxygen saturation was 98.4 \%
(\selectlanguage{ngerman}± 2.0) in room air, 16 (7.5\%) presented respiratory distressand16
(7.5\%) had whistles/wheezingat the auscultation of the thorax. One
hundred and forty-eight (69.4\%) children were admitted in hospital, of
whom 9 (6.1\%) in pediatric intensive care unit.Thirteen (6.1\%)
children needed oxygen therapy during the hospitalization. At LUS
examination the median score was of 2 (IQR 0- 5.5). In particular the
most encountered ultrasound pathological features are the irregularity
of pleural line (33,3\%) and the B lines (46.5\%). Table 1 summarizes
demographic, clinical and LUS findings of children with COVID\selectlanguage{english}-19.

Dividing the sample into 2 age groups, greater or less than one years
old, we got 2 groups of 87 and 126 children. In Table 2, the
demographic, clinical and LUS findings of the two groups are summarized
and compared

From a clinical viewpoint, younger children presented a higher rate of
reduction of food intake (80.4\% \emph{vs} 16.7\%; p = 0.001) and a
higher rate offever (83.9\%\emph{vs} 68.3\%; p = 0.009)compared with
older patients. We also observed in children whit less of 1 year of age
a higher level of oxygen saturationduring the evaluation (99 (+-
1.6)\emph{vs} 98.1 (+- 2.1); p= 0.001) and a lowerneed foroxygen therapy
during the hospitalization (0 \emph{vs} 10.3\%; p= 0.002)than inolder
patients.

Considering LUS pathological features, we observed that the occurrence
of the irregular pleural line and the presence of B-lines were seen more
frequently in younger children (43\% \emph{vs} 60.71\%; p = 0.035 and
53.2\% \emph{vs} 36.8\%; p = 0.013 respectively). Moreover, the presence
of sub-pleural consolidation and pleural effusion were significantly
more common in children whit greater of 1 year of age (21.4\%
\emph{vs}5.7\%; p= 0.001 and 19.8\% \emph{vs} 6.9\%; p= 0.006).

No other significant differenceswere evidencedbetween these two groups.

We found an inverse correlation between the LUS score and the oxygen
saturation during the clinical evaluation (r = \selectlanguage{english}-0.16; p = 0.019).

We also divided the enrolled children in two sample on the basis of the
need for oxygen therapy during hospitalization. We summarized in Table 3
the demographic, clinical and LUS findings of the two groups.

We found that the 13 children who needed oxygen therapy were
significantly older (13 yy 9 mm (11 yy 7 mm- 16 yy 6 mm) \emph{vs} 1 yy
6 mm (4 mm- 9 yy 8 mm); p= 0.001) and reported more frequently chest
pain ( 30.8\% \emph{vs} 5.5\%; p= 0.008) than the other group.

Moreover, childrenwho had needed oxygen therapy presented,during the
clinical assessment, a lower oxygen saturation (94.3 (+- 3.2)
\emph{vs}98.7 (+- 1.5); p= 0.023) and a more frequent hospitalization in
intensive care unit (30\% \emph{vs} 6.1\%; p= 0.017).

Among LUS pathological features, irregular pleural line, sub-pleural
consolidation and pleural effusion were significantly greater in who had
needed oxygen therapy (69.2\% \emph{vs} 31\%; p = 0.007;46.2\%
\emph{vs}13\%; p = 0.006 and 53.8\%\emph{vs} 12\%; p = 0.001,
respectively). Finally, the LUS scores were significantly higher in who
had needed oxygen therapy (8 (3 - 19) vs 2 (0 - 4); p= 0.001, Figure 1).

We also divided our cohorts in children younger than 5 years, 5-11 years
and older than 12 years of age (which reflects the different age groups
that have had access to vaccination).

We found that with increasing age decreased the oxygen saturation value
found at the time of LUS (p= 0.002) so older patients were those who
most frequently needed oxygen therapy (p= 0.001) and hospitalization in
intensive care unit (p = 0.001). At LUS older patients had more
irregular pleural line and B-Lines than younger children (p = 0.001 and
p=0034,respectively). In Table 4, the demographic, clinical and LUS
findings of the three groups are summarized.

\textbf{DISCUSSION}

To our knowledge, this is the first multicenter national study assessing
LUS findings and their prognostic role in a relatively large cohort of
children with microbiologically confirmed SARS-CoV-2 infection. Overall,
we found that children with higher LUS scores and with subpleural
consolidations have a significantly higher risk of being hospitalized or
require oxygen support after initial assessment in the PED.

Our study confirms, on a larger populations, what initially suggested by
smaller pediatric cohorts from Italy, Turkey and Spain, showing that
children with LRTI during SARS-CoV-2 infection can have a cohort of LUS
findings such as vertical artifacts and subpleural
consolidations.\textsuperscript{13-22} Authors from four different
hospitals in Italy, in particular, found vertical artifacts and
subpleural consolidations to be the most common findings, while pleural
effusions were more rare and more described in children with MIS-C.
However, cohorts were mostly limited to less than 50 patients. In
general, these LUS artifacts are in line with what we have learnt from
the past decade of LUS practice in pediatrics. Although the initial role
of LUS has mostly been detecting pneumonia in children, its role has
significantly evolved. \textsuperscript{8} The better understanding of
different semeiotic LUS patterns and of their physical mechanismsled
authors to investigate if specific LUS patterns may better discriminate
different lung conditions. \textsuperscript{23} For example,
pediatricians from Rome found LUS patterns (like large consolidations,
complicated effusions, fix or liquid bronchograms) as more predictive of
bacterial or more severe pneumonia. \textsuperscript{24, 25}Similarly,
two independent teams investigated if some LUS patterns may be more
associated to viral or bacterial pneumonia, both finding that small
subpleural consolidations and vertical artifacts are more frequent in
viral LRTIs, while large consolidations with bronchograms more in
bacterial etiologies. \textsuperscript{26, 27} Therefore, our findings
that vertical artifacts and small subpleural consolidations are more
frequent in Covid-19 pneumonia is in line with what expected from
previous LUS literature in adults with Covid-19 or children with other
viral conditions. \textsuperscript{8}

Our multicenter study allowed us to include a larger number of patients
and provide information about prediction of severity, but also
subanalyses according to age groups. Unsurprisingly, our study found
that children with higher LUS scores of subpleural consolidations had a
higher risks of needing hospitalization or oxygen support. These
findings are in line with a few pediatric studies which included very
small number of children with severe disease, but also confirm studies
from adults with Covid-19.\textsuperscript{13-19} In adults, several
studies have documented how LUS performed in the ED can predict
hospitalization, ventilation support and
deaths.\textsuperscript{10-12}Our findings are not unexpected in light
of recent understanding of the physical bases of LUS.
\textsuperscript{23} In particular, there is growing agreement in
literature that vertical artifacts represent peripheral lung
abnormalities that generate acoustic traps, eventually seen as vertical
lines on LUS. As these abnormalities represent areas of dysventilation
and possibly altered gas exchange, it is not unsurprising that those
children with more abnormalities on LUS may have a higher risk of
developing more severe disease. Similar evidence is already available
from other pediatric respiratory conditions like acute bronchiolitis,
where several studies have documented that children with higher LUS
score have a higher risk of hospitalization, respiratory support and
intensive care unit admission.\textsuperscript{28}

In our study, we performed subanalyses according to age groups. In
general, we found that lung involvement was more significant in children
older than 1 year of age, which is in line with a well-established
although not yet fully understood gradient of more severe disease
according to increasing age.\textsuperscript{1} Some authors have
suggested that better innate immunity in the upper airways might have
contributed to lesser degree of LRTIs in children.
\textsuperscript{29}In our cohort, children younger than 1 year of age
had, in fact, less frequently vertical artifacts and subpleural
consolidations, supporting this hypothesis. However, this age groups may
also have been protected by maternal antibodies, since maternal
vaccinations have started during the study period, although we did not
collect this information.\textsuperscript{30} Conversely, when we
divided our cohorts in children younger than 5 years, 5-11 and older
than 12 years of age (which reflects the different age groups that have
had access to vaccination), the characteristics of LUS patterns were
similar, suggesting that children younger than 5 years of age have a
similar rate of LRTI involvement than older one. These data may have
clinical implications, as can provide further information to both
healthcare workers and parents about the decision of vaccinating or not
younger children, a still debated topic.\textsuperscript{31}

Our study has limitations to address. The most important limit is the
low number of children with critical Covid-19 that required mechanical
ventilation. However, such a severe outcome is very rare and would
require significantly larger populations, a limit difficult to overcome,
even with multicenter studies. Also, our study did not include
populations at higher risk of more severe Covid-19, including children
with comorbidities, black and latino communities, therefore our findings
may not be generalized to different epidemiological contexts. Also,
these data refer to pre-omicro era, and therefore more studies are
needed understand the impact of LUS in these cohorts. Last, we did not
included a cohort of vaccinated children, therefore we have not been
able to evaluate the impact of vaccination on the development of LRTI
during Covid-19 in children.

In conclusion, this national study on children with Covid-19 confirmed
that LUS is able to detect Covid-19 low respiratory tract involvement,
which is characterized by pleural line irregularities, vertical
artifacts and subpleural consolidations. Importantly, children with
higher LUS score have a higher risk of required hospitalization or
oxygen support, further supporting LUS a valid and safe point-of-care
first level tool for the assessment of children with Covid-19. Further
studies will be needed to understand how vaccinations and new variants
may determine a different degree of LRTI in children with Covid-19.

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\end{enumerate}\selectlanguage{english}
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