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\begin{document}

\title{Promoting Factfulness in the Covid-19 pandemic-related policymaking: a
map to understanding school closures}



\author[1]{Raffaella Nenna}%
\author[2]{Hana Zeric}%
\author[1]{Laura Petrarca}%
\author[3]{Enrica Mancino}%
\author[2]{Fabio Midulla}%
\affil[1]{"Sapienza" University of Rome}%
\affil[2]{Sapienza University of Rome}%
\affil[3]{University of Rome}%


\vspace{-1em}



  
  \date{May 15, 2024}


\begingroup
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\selectlanguage{english}
\begin{abstract}
Introduction: In the era of data-driven decision-making, an unacceptable
haziness and inconsistency surrounds the yearlong scientific and public
debate on the school closure policy in the COVID-19 pandemic mitigation
efforts. Aim: The present literature review stems out of the need for a
clear scaffold collecting in one place all current evidence, as well as
helping organizing incoming future evidence, concerning both the role of
schools in driving the Sars-CoV-2 community spread and the
cost-effectiveness of school closure in containing such spread. Methods:
References for this review were initially identified through searches of
PubMed, Scopus and Cochrane Library for articles published from March,
2020, to March, 2021 by use of the terms ``Schools'' ``COVID-19''
``pandemic'' ``clusters'' ``outbreak'' ``seroprevalence''. Further
search was undertaken through Google Scholar and ResearchGate, and
finally through Google. Results: School closure at times of high
background prevalence of COVID-19 should not be considered a measure
implemented to protect the health of children. Children had lower
secondary attack rates than adults and that they infrequently
represented the index case. One year of pandemic has been sufficient for
the emergence of one indication of concern: a potentially increased
burden of paediatric mental health disorders. Conclusions: A fact-based
understanding of what is currently known on such a consequential policy
is required to provide a basis of evidence for an advocacy of either
school closure or school opening at times of high intensity community
transmission of Sars-CoV-2.%
\end{abstract}%



\sloppy


\textbf{Promoting \emph{Factfulness} in the Covid-19 pandemic-related
policymaking:}

\textbf{a map to understanding school closures}

Raffaella Nenna, Hana Zeric, Laura Petrarca, Enrica Mancino, Fabio
Midulla

Department of Maternal Infantile and Urological Sciences, Sapienza
University of Rome, Rome, Italy.

\textbf{Short title:} Understanding school closures during COVID-19
pandemic

\textbf{Conflict of Interest Disclosures:} The authors have no conflicts
of interest relevant to this article to disclose.

\textbf{Funding/Support:} None

\textbf{Abbreviations:}

Coronavirus disease-2019 (COVID-19)

World Health Organization (WHO)

European Union (EU)

United Nations Education, Scientific and Cultural Organization (UNESCO)

reproduction number (Rt)

severe acute respiratory syndrome coronavirus 2 (Sars-Cov-2)

other non-pharmaceutical interventions (NPI)



\textbf{Corresponding author:}

Fabio Midulla MD, PhD

Department of Maternal Infantile and Urological Sciences

Sapienza University of Rome

Viale Regina Elena 324 - 00161 Rome

Tel +39 06 49979363

Fax +39 06 49979363

\emph{midulla@uniroma1.it}



\textbf{Abstract}

\textbf{Introduction} : In the era of data-driven decision-making, an
unacceptable haziness and inconsistency surrounds the yearlong
scientific and public debate on the school closure policy in the
COVID-19 pandemic mitigation efforts. \textbf{Aim} : The present
literature review stems out of the need for a clear scaffold collecting
in one place all current evidence, as well as helping organizing
incoming future evidence, concerning both the role of schools in driving
the Sars-CoV-2 community spread and the cost-effectiveness of school
closure in containing such spread. \textbf{Methods} : References for
this review were initially identified through searches of PubMed, Scopus
and Cochrane Library for articles published from March, 2020, to March,
2021 by use of the terms ``Schools'' ``COVID-19'' ``pandemic''
``clusters'' ``outbreak'' ``seroprevalence''. Further search was
undertaken through Google Scholar and ResearchGate, and finally through
Google.\textbf{Results} : School closure at times of high background
prevalence of COVID-19 should not be considered a measure implemented to
protect the health of children. Children had lower secondary attack
rates than adults and that they infrequently represented the index case.
One year of pandemic has been sufficient for the emergence of one
indication of concern: a potentially increased burden of paediatric
mental health disorders. \textbf{Conclusions} : A fact-based
understanding of what is currently known on such a consequential policy
is required to provide a basis of evidence for an advocacy of either
school closure or school opening at times of high intensity community
transmission of Sars-CoV-2.



\textbf{Introduction}

These days are marking the exact anniversary of the earliest direct
effects of the Coronavirus disease-2019 (COVID-19) pandemic on the
educational sector in the European Union, with Italy as the pioneer
member state. In fact, on March 4\textsuperscript{th}, 2020, the Italian
government issued a ministerial decree that in its first article
declared a nationwide shutdown of pre-schools, schools, and
universities, adapting all didactic activities to distance education. By
March 20\textsuperscript{th}, when the overall prevalence of COVID-19 in
the World Health Organization (WHO) European region was of 151,754 total
reported cases (of which 35\% were in Italy, 16\% in Spain, 14\% in
Germany and 10\% in France), 24 (89\%) out of the 27 countries making up
the European Union (EU) had fully closed their educational facilities
(with Sweden's schools being partially open and Slovenia's and
Bulgaria's fully open). Worldwide, on the same date, the United Nations
Education, Scientific and Cultural Organization (UNESCO) \emph{Global
monitoring of school closures caused by COVID-19} reports a total of 146
country-wide closures, affecting 52.4\% of total globally enrolled
learners. By the end of April 2020, the world had witnessed an
unprecedented international disruption of education, with the peak
reached on April 26\textsuperscript{th}, 2020, with 82.9\% of total
enrolled learners affected (equal to a total of 1,451,874,449 learners
globally).

As local upsurges of COVID-19 multiplied, so did nationwide lockdowns
and concurrent closure of educational facilities. The decision to close
schools early in the epidemic outbreak relied partly on data collected
from mitigation policies to curb previous pandemics {[}1{]} with novel
influenza viruses. In the 1918-1919 influenza pandemic, illness rates
were highest among children of school age, and mortality rates were
highest among infants and young adults other than the elderly {[}2{]}.
In the 2009 H1N1 virus pandemic children and young adults were once
again disproportionately affected {[}3{]}. The indications coming from
already existing disease modelling studies, rapidly supplemented by new
studies published in March-April 2020, evidenced school-closure as a
cost-effective non-pharmaceutical intervention for controlling community
transmission of seasonal and pandemic influenza viruses {[}4{]}. This
would be especially noteworthy at a time when documented effective
pharmaceutical interventions were unavailable. Although the evidence on
the effectiveness of such measures during coronavirus outbreaks were
limited, governments acted uniformly in line with the \emph{WHO
framework for national and local planning and response to the 2009
pandemic} , in which proactive rather than reactive school
closures/class suspension early in a pandemic outbreak were recommended
to achieve the maximal reduction in attack rates. This reduction was
expected to be all the greater if framed within the setting of a general
lockdown. The likelihood of extra-scholastic student aggregation, which
hampers the efficiency of school closures against viral spread, would
then be minimized {[}5{]}.

Nevertheless, due to multiple associated factors, the correlation
between school closure and reproduction number (Rt) drop might not be so
direct, and such a socially drastic intervention might not always
produce an effect of equally drastic magnitude on incidence,
hospitalizations and deaths. Already at the time when the global
decision to close school was taken, evidence existed to challenge the
effectiveness of school closure in the fight against coronaviruses. A
scientific evidence-based review published in 2014 concluded that the
impact of school closure on the size of the pandemic peak was greatest
for viruses whose transmissibility in the community was low (i.e. with a
basic Rt \textless{}2) and whose attack rates were higher in children
than in adults {[}6{]}. Neither of these two conditions appeared to be
applicable to Sars-Cov-2 at the start of the outbreak. However, evidence
also existed in a second systematic review from 2018 that school closure
could prove to be a measure on its own to control infectious spread, not
merely a bridge until other measures are found {[}1{]}.

In the short and medium term, immediate COVID-19 containment was
prioritized over optimal educational continuity and the combined
deployment of all readily amenable interventions did manage to curtail
the first outbreak within the WHO European Region. By May
31\textsuperscript{st}, 2020, incidence and case-fatality ratio
decreased, with 717 deaths out of the 19,995 daily cases as reported to
the WHO compared to the 5,312 daily deaths out of 41,265 daily cases,
which corresponded to the peak of the first wave (registered for the WHO
European region on April 4\textsuperscript{th}, 2020). However, the
steadiness of epidemiological parameters between spring and autumn term,
when schools re-opened in most of Europe, represented only a temporary
hiatus, and a second outbreak started. Although currently the outlook on
the pandemic is still narrow, as new empirical evidence on the severe
acute respiratory syndrome coronavirus 2~(Sars-Cov-2) and its variants
grow on a daily basis, cumulative ongoing research has completely
changed the context in which outbreaks are occurring, gradually
diminishing key unknowns about the virus transmissibility, target
populations, case-fatality, clinical features and available
pharmacological interventions. Mass vaccinations that are occurring
worldwide, and the chronicization of the COVID-19 pandemic, causes a
paradigm shift for paediatricians and whoever else operates in the field
of health promotion for children and adolescents. When considering only
the younger demographic groups, the major problem related to the
pandemic increasingly appears not to be the emergent infectious disease
itself but its long-lasting pervasive indirect consequences. It is our
responsibility to remain updated on both direct and indirect health
effects of COVID-19 on our patient population.

The present literature review will focus on only one such indirect
health effect of the pandemic: the prolonged early school closures and
their precarious re-opening. Early decision-making surrounding
educational facilities across the globe relied on multiple assumptions
and could claim as its main objectives the protection of children, of
educational staff and of the community as a whole from uncontrolled
spread of COVID-19, employing a cost-effective policy. Our aim is to
understand which, if any, of the original assumptions is now fact-based,
and whether the multifaceted latest knowledge on COVID-19 and its
epidemiology in children is accounted for by policymakers, in a world
that has currently lost on average 22 weeks of normal education (UNESCO
data updated to January 25\textsuperscript{th}), and up to more than 50
weeks in some countries (India, USA, Brazil, to cite a few). The large
existing differences in the re-opening policies among different
countries and in the published study types represent an informative
starting point, lessening the risk of both collinearity bias and
population bias compared to literature reviews compiled during the first
wave of the pandemic. School closures were initially used in combination
with multiple other mitigation strategies and testing, as well as
medical care, prioritized symptomatic populations, i.e. including older
adults more frequently than children.

References for this review were initially identified through searches of
PubMed, Scopus and Cochrane Library for articles published from March,
2020, to March, 2021 by use of the terms ``Schools'' ``COVID-19''
``pandemic'' ``clusters'' ``outbreak'' ``seroprevalence''. Further
search was undertaken through Google Scholar and ResearchGate, and
finally through Google. Articles published in English resulting from
these searches and relevant references cited by those articles were then
reviewed.

\textbf{Safety concerns associated to the clinical picture of Covid-19
in paediatric age: do they oppose or support school closure?}

Ever since the early months of the COVID-19 pandemic and up until now,
the aggregated data collected from thousands of confirmed paediatric
cases of COVID-19 initially in China and then increasingly worldwide
points towards reassuring clinical characteristics in \textless{}18-year
olds. All the published systematic reviews and meta-analyses assessing
the disease course in children and adolescents repeatedly reached the
conclusion that the clinical picture of COVID-19 appears to be overall
significantly milder in paediatric than in adult age, with better
prognosis and lower hospitalization rates, as well as low case-fatality
ratios (\textless{}1\% of hospitalized cases){[}7,8{]}. Although symptom
prevalence varies among different studies, the majority of confirmed
cases the Sars-Cov-2 infection presented with either no or few symptoms,
the most commonly reported ones being pyrexia and cough. This appears to
be true both for countries that minimized the exposure of children early
in the pandemic through school closure, and for those that prioritized
keeping children in school throughout the outbreak {[}9{]}.

More severe clinical pictures requiring hospitalization did occur,
reaching a proportion of up to 10 out every 100 cases in the youngest
age group (0 to 4-year olds), but most had favourable outcomes {[}10{]}.
In multivariable analyses of intensive care unit admissions for COVID-19
in paediatric age, the most significant and frequently reported risk
factors were age (\textless{}1 month), pre-existing medical conditions,
and signs or symptoms of lower respiratory tract infection at
presentation {[}11{]}. In addition, one rare COVID-19 related clinical
picture has been defined by the WHO: multisystem inflammatory syndrome
in children (MIS-C), characterized by elevated inflammatory markers,
constitutional signs of organ dysfunction and evidence of SARS-Cov-2
infection. Furthermore, beyond the acute effects of Sars-Cov-2
infection, there are growing concerns about the so-called ``Long-Covid''
in children, or rather the presence of long-lasting symptoms ascribed to
the infection {[}12{]}. From a clinical perspective diagnosing and
successfully treating these severe and long-term clinical pictures of
COVID-19 in the paediatric age is of utmost importance. However, they
neither occur nor lead to unfavourable outcomes frequently enough to be
considered a threat to the health of the paediatric population.

One year into the pandemic, through the public health perspective needed
for pandemic-related policymaking, the claim that COVID-19 in
school-aged children is mostly a mild disease remains undoubtedly
evidence-based. Consequently, school closure at times of high background
prevalence of COVID-19 should not be considered a measure implemented to
protect the health of children.

\textbf{Children in schools as ``super-spreaders'' of Sars-Cov-2: myth
or truth?}

Having established during the first COVID-19 outbreak that protecting
school-aged children from Sars-Cov-2 infection was largely unnecessary,
the rationale for restricting in-presence school attendance lay entirely
in its potential epidemiological benefits in protecting the adults in
their households and the educational staff in their schools. Keeping
students at home directly reduces in-school and public transportation
social contacts for all of pupils, teachers and school staff, thus
limiting the mixing of households and horizontal viral transmission, as
well as limiting the interactions between children, who have been
repeatedly labelled as potential ``super-spreaders'' of infectious
diseases on account of their increased crowding compared to adults. It
also holds secondary pandemic mitigation potential signalling the
severity of the public health emergency and keeping caregivers at home,
albeit harder to quantify.

The questions now arise: in the case of the COVID-19 pandemic and based
on what is currently known, is the idea of children in the
school-setting acting as ``super-spreaders'' plausible? Is it reasonable
to suspect that the second wave of the Sars-Cov-2 virus spread in the
WHO European region has been driven also by school re-opening to
in-presence learning for the 2020-2021 academic year? Two key unknowns
should be investigated to understand Sars-CoV-2 infectiousness in
paediatric age. First, what is the susceptibility of children and
adolescents to the infection, and are there differences in attack rates,
length of the infection and viral shedding between the two age groups?
Second, depending on their susceptibility to the infection and their
opportunity for onward transmission, how likely are children and
adolescents to become the index case of COVID-19 clusters, respectively?

With regards to the first key unknown, preliminary evidence collected
during the first COVID-19 outbreak elucidated that adults appeared to be
at a higher chance of becoming infected with Sars-CoV-2 on exposure
compared to younger age groups. This starting point for interpreting the
infectiousness of Sars-CoV-2 in children comes from a large metanalysis
published at the end of September 2020 {[}13{]} that included 32
studies. Evolving evidence strengthens these preliminary ones: children
and adolescents are not spared from the infection, but they are a
repeatedly underrepresented population of COVID-19 cases. This is
logically true for the very few seroprevalence studies conducted on
symptomatic cohorts {[}14-15{]}, susceptible to an inclusion bias due to
the high prevalence of subclinical infection in the younger populations.
More significantly, this is also true for the few large seroprevalence
studies on random cohorts selected independently of symptoms, in
countries where children were continuously exposed to the infection
because of continued in-presence learning or in which the exposure
probabilities were comparable across generations {[}16-19{]}.
Unfortunately, this epidemiological fact is not established
biologically: when it comes to viral load during the infection and
duration of viral shedding, especially in symptomatic cases, there seem
to be fewer differences between adults and children of all ages
{[}20{]}. Less has been confirmed for asymptomatic cases: the full
demonstration of a significantly shortened or lessened infectiousness of
asymptomatic cases would indisputably strengthen all positions favouring
school opening, giving a reproducible explanation for the observed lower
susceptibility to Sars-CoV-2 of the younger demographic groups.

The consistency of the epidemiological evidence alone encourages the
claim that children should not be a primary target population of
COVID-19 pandemic mitigation strategies {[}21{]} and has been used as
sufficient evidence to disclaim the role of children as super-spreaders
{[}22{]}, but it does not disregard the risk that children are
susceptible to the infection and may hence transmit it both in their
classroom and within their household. As a very recently published
modelling study {[}23{]} discloses, when it comes to the dangers of
seeding COVID-19 cases across a large community through extensively
undetected school clusters, even an extremely low number of child index
cases might eventually amplify and result in a sizeable community spread
with increased overall incidence and mortality. Confirming this concern
are two large early studies coming from Asia {[}24,25{]}. A number of
other studies strongly contradict this evidence, 57 of which were
included in an international metanalysis on household Sars-CoV-2
transmission clusters during the first pandemic wave {[}26{]}, finding
that children had lower secondary attack rates than adults and that they
infrequently represented the index case. This data was partly
re-confirmed for the second wave in a large UK study {[}27{]}.

\textbf{Open schools or school re-opening: under which conditions has it
jeopardized epidemic control in 2020-2021}

The disparity of evidence brings us to the second key unknown we had
previously identified: what have we learnt about the role that
transmission among children and adolescents has played at the population
level? Epidemiological data coming from countries that have prioritized
continuous in-presence schooling especially for the younger age groups,
such as Iceland, France, Norway, Sweden, Estonia, Denmark, and studies
monitoring the effect of re-opening of schools in countries that had
previously kept them closed, such as Italy, Germany, USA, UK, can be
greatly informative to understand the real-life epidemiological
consequences of leaving complete school closure to be a last resort in
controlling the COVID-19 pandemic. Although multiple contextual
variables could be factored out to account for any incompatibilities in
this large pool of evidence, three appear to be of key importance: the
age of the school-children involved, the background prevalence, and the
infection control measures initiated concurrently with opened
educational facilities.

\emph{The lower the age of schoolchildren, the lower the risk of
school-related uncontrollable infection clusters.}

Evidence coming from retrospective and cross-sectional studies early in
the pandemic {[}28-29{]} and from larger surveillance studies relating
to the second peak of the pandemic, strongly supports minimal
transmission rates in European day-care centres and primary schools,
both for pupils and educational staff {[}30-32,42-44{]}. Significantly,
this finding remains consistent also in areas of high COVID-19
background incidence and after systematic contact testing of each
paediatric index case. Conversely, the only large outbreak of infection
among younger children that has been reported in the literature is most
likely explained by particular epidemiological features and does not
provide conclusive counterevidence {[}33{]}. For older children and
adolescents, larger or more numerous clusters of COVID-19 traced back to
school environments have been evidenced, albeit very rarely, pointing to
a potentially non-negligible transmissibility of Sars-CoV-2 in older age
groups that could be explained by social as well as biological factors
{[}13,34-35{]}.

\emph{We should target community transmission first to protect
educational settings, and not vice versa.}

Recent empirical work from multiple countries that correlates school
re-opening to local Rt direction changes and secondary infection
clusters increasingly confirms earlier findings of minimal contribution
of educational settings to the community COVID-19 growth rates
{[}36-38,52-54{]}: open schools of all grades may be considered safe and
will not act as amplifiers of Sars-CoV-2 spread at times of low COVID-19
background prevalence. In fact, it appears that adults, and not
children, play a key role in bringing the virus into their households
{[}39,55{]}, and that in-school COVID-19 incidence is directly
consequential to local background prevalence {[}40,41,56,57{]}. An
Italian study demonstrated that the COVID-19 incidence in young adults
(20-49 year-olds) was the earliest to peak only to be later followed by
younger age groups, making young adults the likeliest main drivers of
the second pandemic wave in Italy. With data coming from 97\% of Italian
public schools, this multidimensional study provides no evidence of a
driving role for schools {[}36,52{]}. This observation is further
corroborated by a studies revealing young adults as consistently the
group with the highest incidence of COVID-19 during the second wave
{[}43,44{]}. Evidence seems to suggest that policies targeting young
adults could be significantly more effective than those targeting
children and adolescents, which could then consequently be themselves
partly protected from the infection.

\emph{Potentially successful alternative strategies and proactive
measures avoiding school closure are available both at general
population level and within schools.}

Although high-quality evidence is still lacking to confirm no benefit in
pandemic control in countries that relied the most on school closure and
reciprocally no negative impact from minimizing school closures, reports
found in the grey literature, in particular by the ECDC, do imply such a
trend. The modelled protective potential of school closures {[}45{]}
appears to be comparable to that of other non-pharmaceutical
interventions (NPI), such as bans on mass gatherings or closure of
non-essential businesses, implying that widespread school closures could
be circumvented through ready employment of alternative strategies,
while still achieving minimized Sars-CoV-2 spread. This was exemplified
in real-life by the minimal and only temporary closures of Taiwanese
schools throughout 2020 {[}46{]}. Furthermore, as synthesized in a large
systematic review {[}47{]}, multiple organizational, environmental and
surveillance measures have been implemented heterogeneously worldwide to
minimize the risk of in-class infection, including highly effective
test-and-trace strategies, decreased class size, opening for specific
cohorts in a staggered timetable, lessons held outdoors, physical
distancing as well as hygiene measures in the classroom, the creation of
social bubbles limiting contacts between those who rarely meet, and the
instruction to stay at home when sick {[}48-50{]}. Although successfully
curtailed school-related outbreaks are less likely to be reported in the
literature than outbreaks that have occurred, we have sufficient
real-world evidence indicating that different types of infection control
measures may effectively either avert or minimalize COVID-19 clusters
among students {[}51-54{]}. While the efficacy of each measure has been
extensively modelled, very few experimental and quasi-experimental
studies have been published assessing the effectiveness of specific
measures, including one finding that lower physical distancing policies
may safely be adopted in school settings {[}55{]}. A larger pool for
evidence extrapolation is now needed to better tailor guidelines for
safe school re-opening. Acquiring this data would provide critical
knowledge for all future cost-effective policymaking minimizing
educational losses even at times of high-intensity coronavirus spread in
the community.

\textbf{Prolonged school closure may be detrimental not only to
education, but also to health:}

Across the globe, educational facilities hold a pivotal role in the
promotion and maintenance of long-term health, which is complementary to
their didactic role. While online schooling partly ensured the
continuity of their didactic role, school-based screening and prevention
programs were severely disrupted throughout 2020-2021. More time will
need to elapse before the consequences of such loss become evident, but
a vast heterogeneity of the potential harmful consequences that
prolonged school closure and home confinement introduces for the
school-aged population and their families, were recognized early in the
pandemic by the scientific community operating in the field of
developmental paediatrics {[}56,57{]} and child psychiatry {[}58{]}.
Multiple streamlines should be included in such a lifelong investigation
of today's youth, examining changes in the epidemiology of obesity and
malnutrition {[}59{]}, immunization rates, unattended domestic violence
and child abuse {[}60{]}, delays or precocity in cognitive, physical or
social growth {[}57{]}, later diagnoses of developmental conditions, and
overall rates of health inequity {[}61{]}. However, one year of pandemic
has been sufficient for the emergence of one indication of concern: a
potentially increased burden of paediatric mental health disorders.

Even on its own, a public health emergency creates multiple stressors
for children and adolescents irrespective of their previous mental
health status, due to fear of infection, elevated levels of stress and
anxiety of caregivers {[}62,63{]} and recommended or mandated social
isolation {[}64{]}. These are further exacerbated with school shutdowns,
especially if protracted to an indefinite time, and are supplemented by
other stressors, including a disrupted routine, reduced socialization
and physical activity, increased screen time and social media
consumption, increased boredom, unhealthy or insufficient nutrition,
exposure to parental burnout {[}63{]}, stressors related to school
dropout, and others. The cumulative effect of these stressors was partly
registered in low-to-high quality studies published early in the
pandemic and during lockdowns, consistently finding scores above
thresholds for psychological distress, anxiety, depression in
substantial a percentage of participants {[}64-69{]} and, when
comparison was possible, higher than in pre-pandemic cohorts {[}70{]}.
Adolescents were found to represent a particularly vulnerable cohort
{[}71{]}. Concomitantly, the clinical frontlines reported both a
significant decline in the incidence of admissions for psychiatric
emergencies during lockdowns {[}72-74{]} and increased suicide ideation
and self-harm rates {[}75{]}. Such a rise in psychiatric emergencies
overall, and specifically in suicide behaviours, is already documented
in manifold reports and news article easily found through a Google
search: we now await high-quality published studies empirically
confirming this alarming trend beyond the grey literature, framing it
developmentally as well as clinically. In the difficult trade-off of
school closures as pandemic mitigation strategies, policymakers will
need a larger body of strong evidences regarding the so-called ``hidden
epidemic'' hitting the younger populations.

\textbf{Conclusions}

Overall, opening schools and keeping them open in the context of the
Sars-CoV-2 pandemic is theoretically possible, although behaviourally
challenging and unfeasible if educational facilities or testing services
are inadequate. Based on the data synthesized here, we can establish
that, contrary to other respiratory viruses, children are not the
primary targets of Sars-CoV-2 infection, transmission and disease, and
schools may avoid becoming infection hubs for them, their teachers, the
educational staffs and their households. It also appears that the second
wave of the Sars-CoV-2 virus spread in the WHO European region has been
unrelated to school re-opening. The pandemic exit strategy should
necessarily prioritize an increased vigilance towards signs of negative
health outcomes of the public health emergency on the younger
population. A redeployment of public resources in such a direction might
soon become necessary: the urgency may shift away from COVID-19 and
towards increased prevalence of non-communicable and mental health
disorders in the general population. We urge public health institutions
across the globe to continue planning rescue programs and school
restructuring in the near future to overcompensate for all that has been
lost now, to avoid the future blame of the increasingly
labelled\emph{Covid generation} for not having used today all the
available evidences to protect their long-term global health.

In conclusion, the clear benefits justifying the indiscriminate use of
school closures as first-resorts at times of intensified viral spread in
the community may increasingly no longer be current. Larger and longer
prospective studies with widespread screening and mechanistic genomic
tracing are now needed for risk stratification for all virus variants of
concern, in different socio-economic contexts, background demographics
and school designs. It is our duty to encourage investments in this type
of research and best-informed policymaking, and to discourage all
generalizations and unverified assumptions in politicized debates for
school closure or opening by the lay public.



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