key: cord-0830569-inivix80
authors: Rovida, F.; Cereda, D.; Novati, S.; Licari, A.; Triarico, A.; Marseglia, G.L.; Bruno, R.; Baldanti, F.
title: Low risk for SARS-CoV2 symptomatic infection and early complications in pediatric patients during the ongoing CoVID19 epidemics in Lombardy
date: 2020-06-12
journal: Clin Microbiol Infect
DOI: 10.1016/j.cmi.2020.06.006
sha: e13fa67e13247c10a9c336713eb22aed2e5b36f4
doc_id: 830569
cord_uid: inivix80

nan

Strikingly, among a total of 3220 SARS-CoV-2 positive patients, only 0,80% (27/3220) were pediatric (<18 years), while 99,2% were adult (>18 years). A complete picture of the age distribution of all positive cases is reported in figure 1 A-B. The age of pediatric patients ranged from 4 months to 17 years (median, 11 years). 48% (13/27) were aged 12-17 years, 26% (7/27) were aged 6-11 years, and 26% (7/27) were <6 years.

In addition, the low frequency of pediatric CoVID-19 cases, it must also be noted that the majority of them were clinically mild (70%, 19/27), and SARS-CoV-2 detection was possible because of the proactive search in contacts of more evident CoVID-19 presentations. At the time of writing, none of the pediatric patients with confirmed SARS-CoV-2 infection diagnosed in our laboratory required Intensive Care Unit (ICU) medical admission.

Our report agrees with the data already reported in China [2, 3, 4] , supporting the hypothesis that clinically evident CoVID-19 is less frequent and milder in the pediatric population [5] . The data presented here, collected within the context of an organized surveillance program, corroborate previous observations and underline the need to understand better the clinical spectrum of CoVID-19 in the pediatric population.

Indeed, all other viral respiratory infections are mostly concentrated in the pediatric population. CoVID-19 affects children and young adults less severely than the middle-aged or aged population, which contrasts with experience from previous viral pandemics, including influenza A.

Furthermore, other respiratory viral infections, including influenza, respiratory syncytial virus, human metapneumovirus, adenovirus, parainfluenza virus, measles, picornaviruses and other coronaviruses, tend to cause more severe disease in the pediatric population. A common explanation for this phenomenon is the lack of pre-existing immunity to most of these viral families, with subsequent maturation of the immunologic repertoire after each subsequent exposure to viral pathogens. In the context of SARS-CoV-2, lack of antecedent immunity to viral pathogens does not appear to be detrimental for severe disease. Recently, an age-dependent expression of the SARS-CoV-2 receptor, Angiotensin-Converting Enzyme 2 (ACE 2), has been demonstrated in the nasal epithelium [6] . In particular, children had a lower ACE 2 expression compared with adults. These results may help explain the lower rates of SARS-CoV-2 infection in children. Much has still to be explained regarding this new and mysterious beta-coronavirus. 

Detection of 2019 novel coronavirus (2019-nCoV) by real-time RT-PCR

Characteristics of pediatric SARS-CoV-2 infection and potential evidence for persistent fecal viral shedding

Clinical characteristics of coronavirus disease 2019 in China

Early transmission dynamics in Wuhan, China, of novel Coronavirus-infected pneumonia

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection in Children and Adolescents: A Systematic Review

Nasal Gene Expression of Angiotensin-Converting Enzyme 2 in Children and Adults

There were no conflict of interest.

We thank Daniela Sartori for manuscript editing.

This study was supported by funds from Lombardy Region, Milan, Italy.

Data collection and analysis of cases and contacts was part of a continuing public health outbreak investigation and were thus considered exempt from institutional review board approval.