Background: Mycoplasma pneumoniae is a common cause of respiratory tract infections in children, but neurological complications, including encephalitis, are increasingly recognized. Basal ganglia involvement is rare, and a poorly characterized feature of meningoencephalitis, with clinical consequences being inconclusive. Methods: We report two pediatric cases of Mycoplasma pneumoniae-related meningoencephalitis with bilateral basal ganglia lesions seen on MRI. A literature review was conducted using PubMed, Scopus, and Web of Science to identify reports of M. pneumoniae-related meningoencephalitis in children, and related MRI findings. Results: Both patients (12-year-old male and 14-year-old female) presented with acute meningoencephalitis syndrome and had marked mononuclear pleocytosis. In both patients M. pneumoniae was confirmed with serological assay from serum sample, while in one patient M. pneumoniae was also confirmed by PCR from pharyngeal swab. Both exhibited bilateral basal ganglia lesions, with complete regression observed during follow-up. Treatment with corticosteroids led to full recovery in both cases. After a literature search, a total of 21 patients had basal ganglia involvement reported. Conclusions: Literature suggests variable MRI findings in pediatric M. pneumoniae encephalitis, with basal ganglia involvement being uncommon and rarely reported, especially among older children. While diagnostic challenges related to extrapulmonary manifestations of the infection persist, basal ganglia involvement could aid in diagnosis, especially in older children presenting with meningoencephalitis along with pronounced pleocytosis when respiratory symptoms are absent or mild.

Aim: Infectious diseases are among the most commonly reported diseases in internationally adopted children. Pre-arrival medical evaluation is not mandatory for internationally adopted children arriving in Croatia, and post-arrival screening for infectious diseases is important to prevent complications and reduce the risk of transmission to the adoptive family and the community. This study aimed to assess the prevalence of infectious and vaccine-preventable diseases in internationally adopted children at the University Hospital for Infectious Diseases „Dr. Fran Mihaljević“ in Zagreb, Croatia. Methods: We retrospectively reviewed all medical data from hospital records of internationally adopted children from 2012 to 2024. We included asymptomatic internationally adopted children examined for post-arrival screening and internationally adopted children with post-arrival symptoms (e.g. fever, cough, haematuria, diarrhea) who have not done a screening for infectious diseases after arriving in Croatia. Results: All 54 included children were adopted from orphanages in the Democratic Republic of Congo. At least one infectious disease was diagnosed in 57 % of all included children and 45 % were asymptomatic upon presentation. The most prevalent were malaria and giardiasis. We observed high seroprevalence for measles and low for pertussis. Conclusions: With this study, we want to increase awareness about the importance of post-arrival screening (especially for malaria, giardiasis, and urinary schistosomiasis) and vaccination among healthcare professionals, to improve the healthcare of internationally adopted children from the Democratic Republic of Congo. Moreover, we suggest developing a national screening protocol for infectious diseases in all IAC arriving in Croatia.

Background: Enteroviruses, members of the Picornaviridae family, typically cause asymptomatic or mild infections. However, they can also result in central nervous system (CNS) involvement, with transverse myelitis (TM) occurring only on rare occasions. TM is a syndrome characterized by acute or subacute spinal cord dysfunction, leading to neurological deficits below the level of the lesion. Case report: We report a case series of eight pediatric patients admitted over a three-month period, June to August 2024. All patients presented with ataxia and/or other neurological symptoms, alongside abnormal cerebrospinal fluid (CSF) findings. Although ataxia is commonly associated with cerebellitis, magnetic resonance imaging (MRI) in this cohort revealed findings consistent with TM. Notably, all patients demonstrated similar MRI abnormalities. The onset of symptoms occurred over a short time during an enterovirus epidemic. Enteroviral RNA was detected, or the virus was isolated in seven patients, while one patient had a close epidemiological link to the virus. All patients achieved full recovery following immunomodulatory therapy. Conclusions: This case series underscores that ataxia may be an atypical symptom associated with TM. Furthermore, there was a notable distinction between the clinical presentation and neuroradiological findings. Immunomodulatory therapy with immunoglobulins and corticosteroids has been shown to be effective and safe, supporting the hypothesis of an immune-mediated pathogenesis in these patients.

Multisystem inflammatory syndrome in children is a novel entity first described in April 2020. It is a complication of COVID-19 that appears with a latency of 2-6 weeks and is characterized by fever, multiorgan involvement, and elevated inflammatory markers. Diagnosis is based on certain diagnostic criteria, and in these recommendations we chose the World Health Organization case definition. Patients should be treated with intravenous immunoglobulin and glucocorticoids together with other symptomatic and supportive measures. Follow-up should be at least a year-long, and even longer in case of cardiac complications. The aim of these recommendations is to help clinicians in diagnosing and treating this disease.

To the Editors: We read the recent publication by Hobbs et al1 on the characteristics and complications of COVID-19 in hospitalized infants with interest. The authors reported that the most severe cases were in infants <6 months of age, with respiratory complications being the most frequent. Among all patients (severe and nonsevere), there were no reports of apnea. To the best of our knowledge publications about COVID-19 associated apnea in infants are scarce2 and published before the delta variant of SARS-CoV-2 became widespread. Here, we present 5 cases of apnea as the initial manifestation of uncomplicated COVID-19 in young infants treated at our hospital in Croatia (November 2021 to February 2022) (Table 1). The definition of apnea agreed by the American Academy of Pediatrics was used. Except for 1 moderate preterm neonate with intraventricular hemorrhage and another newborn with a small patent foramen ovale, the other infants were healthy with unremarkable prenatal and neonatal medical histories. At the time of admission 4 children appeared well with normal vital signs, although 1 child was hypoxic with physical findings suggestive of bronchiolitis. In all patients, we ruled out other common infectious causes of apnea (normal blood tests, excluded other respiratory viruses and pertussis) and several different diagnoses (cardiac and neurological abnormalities). The association between apnea and COVID-19 was further confirmed by documentation of SARS-CoV-2 infection among patient’s family members and rapid clinical improvement with complete recovery with or without methylxanthine treatment. TABLE 1. - Demographic, Clinical, Diagnostic and Treatment Data of Patients Case 1 Case 2 Case 3 Case 4 Case 5 General data Gender Male Female Male Male Female Birth age (wks) 38 39 38 34 40 Comorbidities None None None None None Age (d) 13 91 23 36 32 Date November 15, 2021 November 18, 2021 November 19, 2021 January 28, 2022 February 2, 2022 Apnea (duration) November 15–17, 2021 November 18, 2021 November 20–22, 2021 January 28–29, 2022 February 2–March 2, 2022 Fever/cough +/+ +/+ +/+ +/+ –/– Diagnostic procedures SARS-CoV-2 * + + + + + Respiratory viruses † – – – – – BP/BPP ‡ – – – – – Chest radiograph Normal Normal Normal Normal Normal Cranial ultrasonography Normal Not done Normal IVH § Normal Transthoracic echocardiography PFO ¶ Not done Normal Normal Normal Treatment (d) Oxygen 6 1 1 – – Aminophylline 6 – 4 – – *PCR from NP swab.†Multiplex PCR from NP aspirate for influenza A/B, human metapneumovirus, respiratory syncytial virus, bocavirus, adenovirus, enterovirus, coronaviruses, parainfluenza virus types 1, 2, 3, and 4, parechoviruses and rhinoviruses.‡PCR from NP aspirate for BP/BPP.§IVH (grade 2).¶PFO (3–4 mm).BP/BPP indicates Bordetella pertussis/parapertussis; IVH, intraventricular hemorrhage; NP, nasopharyngeal; PCR, polymerase chain reaction; PFO, patent foramen ovale. Apnea in infants can result from prematurity or other underlying conditions. Infants presenting with apnea were previously categorized as “apparent life-threatening events” but in 2016 American Academy of Pediatrics replaced this term to “brief resolved unexplained events” (BRUE) to distinguish benign events from life-threatening and to improve clinical management. However, based on many clinical guidelines and reports, infants with evidence of apnea are excluded from BRUE and should undergo further cardiac, neurologic, gastroenterologic, and hematologic evaluations to establish the underlying disorder.3,4 Infectious diseases are common causes of apnea in young infants, especially in preterm neonates and infants <2 months of age. Sepsis, central nervous system, or respiratory infections are those which need to be excluded, especially when accompanied by fever or respiratory symptoms. The 2 principal infectious causes of apnea are respiratory syncytial virus and Bordetella pertussis; however, other respiratory viruses have also been reported in a small percentage of cases.3–5 We observed that SARS-CoV-2 can cause apnea in young infants with otherwise asymptomatic or benign COVID-19. We also noticed a cluster of described clinical manifestation during predominant circulation of the delta (until late December 2021) and omicron (from January 2022) variants in the Croatian population. Based on our report, we suggest that testing for SARS-CoV-2 should be part of the initial evaluation of apnea in infants who were <3 months of age presenting to emergency pediatric departments. Additionally, although the majority of neonatal SARS-CoV-2 infections are mild, caregivers should be aware of this potentially life-threatening complication, especially in very young patients who are discharged or treated in outpatient settings.

Objective: Explore clinical characteristics, treatment and outcome of pediatric COVID-19. Methods: Retrospective analysis of children under 18 admitted for COVID-19 to University Hospital for Infectious Diseases „Dr Fran Mihaljević“, Zagreb between July 1st 2020. and January 1st 2022. We analyzed demographic data as well as data on clinical characteristics, treatment and outcome. Findings: 136 children were included, half of them being infants. There was a slight male predominance. Disease severity was mild in most cases (71%). Fever and respiratory symptoms (cough, rhinorrhea, tachi/dyspnea) were the most common. Gastrointestinal symptoms and neurologic involvement occurred in less than 20% and 10% of children, respectively. Oxygen supplementation was applied in a quarter of cases, and mechanical ventilation in 4%. Outcome was good overall – none of the children died and all were discharged cured or recovered. Conclusion: COVID-19 is generally a mild disease in children. Fever and cough were the most common symptoms in hospitalized children. © 2022 Hrvatski Lijecnicki Zbor. All rights reserved.

To The Editors: Since the emergence of the novel coronavirus SARS-CoV-2, great attention was drawn to the multisystem inflammatory syndrome in children (MIS-C) – a life-threatening complication. Although conduction disorders are uncommon in childhood, a growing number of mild cases address these abnormalities with MIS-C.1 Usually they include prolonged QTc interval, first-degree atrioventricular block (AVB), right bundle branch block, ST-segment changes and tachyarrhythmias.1 This report illustrates the importance of cardiovascular monitoring in patients with MIS-C admitted to the pediatric intensive care unit (PICU). A previously healthy 9-year-old boy presented with a high fever of 39.4°C and vomiting lasting for 4 days. He tested positive for SARS-CoV-2 by RT-PCR from a nasopharyngeal swab. On physical examination, the patient was hypotensive (blood pressure of 90/50 mm Hg) and tachycardic (heart rate of 103 beats per minute). Initial laboratory tests revealed a WBC count of 6.3 × 109/L with relative neutrophilia (85%), elevated inflammatory markers (procalcitonin of 0.949 mcg/L, C-reactive protein of 165.6 mg/L, ferritin of 280.3 mcg/L, interleukin-6 of 352.8 ng/L, fibrinogen of 7.6 g/L and D-dimers of 4.45 mg/L) and elevated cardiac markers (troponin of 0.970 mcg/L and NT-pro-BNP of 6092 ng/L). Upon sudden development of bradycardia (heart rate of 45 beats per minute), electrocardiogram (ECG) revealed Mobitz type I second-degree AVB. Echocardiography documented moderate mitral regurgitation and normal left ventricular ejection fraction without pericardial effusion. Treatment in the PICU included empiric antimicrobial therapy with ceftriaxone and clindamycin, intravenous immunoglobulins, glucocorticoids, vasopressor support and diuretics. The fever receded after 7 days. The blood cultures were negative. However, ECG raised suspicion of possible progression to more advanced blocks with a P:QRS ratio of 3:1 while the cardiac markers were still elevated (troponin of 0.062 mcg/L and NT-pro-BNP of 4110 ng/L). Serial ECG revealed spontaneous conversion to normal sinus rhythm within 3 days, confirmed by the 24-hour ECG monitoring. The patient was discharged after 14 days. At the 3- and 6-months follow-up, a 24-hour ECG recording and ergometric testing showed normal rhythm without any signs of AVB. Mobitz type I second-degree AVB secondary to MIS-C is clinically difficult to recognize due to the predominant development of hypotension and tachycardia upon admission, whereas low and irregular heart rate would be indicative of such conduction disorder in a child without MIS-C.2 Several studies explored acute cardiovascular manifestations in MIS-C where Valverde et al included 286 cases and Regan et al described serial ECGs in 63 cases with a median of 5 ECGs per patient.1,3 Neither study reported a second-degree AVB. All patients with severe MIS-C require PICU admission due to possible rapid hemodynamic deterioration. Furthermore, all patients with Mobitz type I second-degree AVB should be admitted and monitored due to possible progression to bradycardia, hypotension and/or higher degree AVB.2 In conclusion, MIS-C cases started having unique presentations, including cardiac conduction disorders. Second-degree AVB can be a presenting finding of MIS-C and high clinical suspicion must be held for patients presenting with signs of shock.

Background Campylobacter jejuni is a common cause of acute gastroenteritis, but central nervous system infections are rare manifestations of Campylobacter infection. Therefore, C. jejuni trauma-related subdural hygroma infection in children is poorly described in the literature. Case presentation We described a 2-year old boy with lobar holoprosencephaly presenting with subdural hygroma following head trauma. C. jejuni infection was confirmed from a subdural hygroma sample by culture as well as by DNA sequencing of a broad range 16S rDNA PCR product. Cerebrospinal fluid from the ventriculoperitoneal shunt remained sterile. Combined neurosurgical and antimicrobial treatment led to complete recovery. Review of the literature showed that the most common manifestation of Campylobacter central nervous system infection is meningitis, mostly in neonates, and subdural hygroma infection was described for only one case. Conclusions Subdural hygroma infection caused by C. jejuni is a rare clinical condition in children. Molecular methods represent an important tool for the detection of rare or unexpected pathogens. No standard recommendations for antimicrobial treatment of C. jejuni subdural space infection in children are available, but meropenem treatment combined with surgery seems to be an effective approach.

There has been an increase in reported TBE cases in Europe since 2015, reaching a peak in some countries in 2020, highlighting the need for better management of TBE risk in Europe. TBE surveillance is currently limited, in part, due to varying diagnostic guidelines, access to testing, and awareness of TBE. Consequently, TBE prevalence is underestimated and vaccination recommendations inadequate. TBE vaccine uptake is unsatisfactory in many TBE-endemic European countries. This review summarizes the findings of a scientific workshop of experts to improve TBE surveillance and vaccine uptake in Europe. Strategies to improve TBE surveillance and vaccine uptake should focus on: aligning diagnostic criteria and testing across Europe; expanding current vaccine recommendations and reducing their complexity; and increasing public education of the potential risks posed by TBEV infection.

COVID-19 in childrenaccounts for up to 8% of all the cases and is less severe than in adults. Thiscould be an underestimation. A significant number of children are asymptomatic.Symptomatic infection is hard to distinguish from other respiratory tract viralinfections based on symptoms and laboratory results. Anosmia is the onlysymptom in children that is highly suggestive of COVID-19. Infected childrenmostly have a positive household member. However, the role of children inSARS-CoV-2 transmission is still controversial. Data suggest thatschoolchildren have a greater impact in SARS-CoV-2 transmission compared to youngerchildren. Multisystem inflammatory syndrome in children is a new entityreported since April 2020 and is considered a rare complication of SARS-CoV-2infection. It occurs in previously healthy older children and adolescentspresenting with multisystem involvement and elevated inflammatory markers. Mostchildren respond well to immune-modifying therapy. Treatment of COVID-19in children is based solely on data received from adults and consists ofsupportive treatment and, in rare occasions, antiviral therapy (remdesivir),corticosteroids (dexamethasone) and monoclonal antibodies (tocilizumab).Further studies in children are needed in order to better understand thisdisease. This article discusses clinical presentation and therapeutic optionsfor COVID-19 in children.

Background Acute mastoiditis (AM) is a frequent complication of acute otitis media in children. Osteomyelitis of the temporal bone, extra and intracranial abscesses, meningitis or sinus venous thrombosis (SVT) are common complications of AM. Over the last decade, a change in the etiology of AM in pediatric patients has occured. Rates of bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catharralis are declining, while other pathogens, manly Group A Streptococcus and Fusobacterium necrophorum are increasing. Case Report Summary A 4-year old boy was admitted at University Hospital for Infectious Diseases ‘Dr. Fran Mihaljević’, Zagreb, during October 2019 on the 4th day of fever, vomiting, respiratory symptoms and earache. On physical examination, his vital signs were normal, he had redness and edema of the right eye without internal and external ophthalmoplegia. Otoscopy revealed purulent otorrhea in the right external auditory canal. Neck stiffness was present without a focal neurological deficit. Laboratory tests revealed elevated inflammatory parameters with a white blood cell (WBC) count of 27x109/L and C-reactive protein of 213,4 mg/L. Lumbar puncture revealed pleocytosis of 7087 white cells/μL (neutrophils 85,3%), moderately elevated protein level (0,86 g/L) and glucose concentration of 1,9 mmol/L. Empiric intravenous antibiotic therapy with ceftriaxone was started at the admission. Despite treatment, the patient was febrile with the onset of headache and somnolence. The patient underwent contrast-enhanced computer tomography (CT) which revealed signs of complete opacification of mastoid air cells with diffuse soft-tissue thickening and areas of enhancement anterior to the orbital septum along with the increase in attenuation of the right cavernous sinus. Cranial Magnetic Resonance Imaging (MRI) showed contrast filling deficit in the right cavernous sinus due to sinus thrombosis. Microbiological analysis of the cerebrospinal fluid and purulent exudate releaved Fusobacterium spp. Blood culture remained sterile. Antibiotic therapy was changed to metronidazole with the addition of low molecular weight heparin. Metronidazole therapy was maintained for 24 days, and anticoagulant therapy with warfarin was continued after the hospital discharge. The patient recovered completely without neurological sequelae. Discussion A growing incidence of Fusobacterium spp AM and its high rate of complications suggest the need for greater awareness of this pathogen. Based on recent studies, most authors recommend the use of metronidazole in combination with third generation cephalosporin in the treatment of AM in children.

1 Medicinski fakultet Sveučilišta u Splitu 2 Medicinski fakultet Sveučilišta u Rijeci 3 Klinika za dječje bolesti Kantrida, Klinički bolnički centar Rijeka 4 Specijalistička pedijatrijska ordinacija Trogir 5 Dječja bolnica Srebrnjak 6 Klinički zavod za mikrobiologiju i parazitologiju, Klinički bolnički centar Split 7 Klinika za dječje bolesti, Klinički bolnički centar Sestre milosrdnice 8 Opća bolnica Knin 9 Opća bolnica „Dr. J. Benčević“ Slavonski Brod 10 Fakultet za dentalnu medicinu i zdravstvo Sveučilišta u Osijeku 11 Stomatološki fakultet Sveučilišta u Zagrebu 12 Klinika za dječje bolesti Zagreb 13 Opća bolnica Dubrovnik 14 Klinika za infektivne bolesti „Dr. Fran Mihaljević“, Zagreb 15 Medicinski fakultet Sveučilišta u Zagrebu 16 Klinika za dječje bolesti, Klinički bolnički centar Zagreb 17 Medicinski fakultet Sveučilišta u Osijeku Preporuke | Recommendations

The infection risk among frontline health care workers (HCW) is one of the most concerning aspects of COVID-19 Knowledge about SARS-CoV-2 transmission is still insufficient However, direct, person-to-person contact appears to be the main route Secondary transmission can also occur and intensive care units have shown greater contamination than general wards Risk of transmission by infectious aerosols distributed through the ventilation system duct is considered to be very low Screening and triaging everyone entering a health care facility is crucial in order to prevent rapid spread among hospital personnel and patients Recommendations on airborne precautions in the health care setting vary by location, but are universally to be implemented when aerosol-generating procedures are performed Surgical masks or respirators are currently critical supplies that should be reserved for HCW Both types of masks need to be used in combination with other personal protective equipment measures COVID-19 patients should be cohorted and only patients undergoing aerosol generating procedures should be placed in airborne infection isolation rooms

Od pojave u prosincu 2019. pandemija uzrokovana SARS-om -CoV-2 veliki je javnozdravstveni problem u svim zemljama svijeta.Virus se prenosi prvenstveno inhalacijom kapljica respiratornih sekreta od bolesnika ili asimptomatskog nositelja i visoko je zarazan.Klinički je bolest u djece slična drugim akutnim respiratornim infekcijama uz predominantne simptome gornjeg dišnog sustava, akatkad može progredirati i do pneumonije s razvojem akutnog respiratornog distres sindroma i multiorganskog zatajenja. Bolest jeblaža u djece nego u odraslih s niskom smrtnošću, a čini se da dojenčad i mala djeca imaju nešto težu kliničku sliku. Dijagnoza sepostavlja dokazom virusnoga genetičkog materijala u respiratornim uzorcima (uglavnom brisevi nazofarinksa i orofarinksa) metodom lančane reakcije polimeraze. Liječenje je većinom simptomatsko, a kod teških i kritičnih oblika može se razmotriti uporaba nekog od antivirusnih lijekova (lopinavir-ritonavir, remdesivir, hidroksiklorokin).

BackgroundTo date, few data on paediatric COVID-19 have been published, and most reports originate from China. This study aimed to capture key data on children and adolescents with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection across Europe to inform physicians and health-care service planning during the ongoing pandemic.MethodsThis multicentre cohort study involved 82 participating health-care institutions across 25 European countries, using a well established research network—the Paediatric Tuberculosis Network European Trials Group (ptbnet)—that mainly comprises paediatric infectious diseases specialists and paediatric pulmonologists. We included all individuals aged 18 years or younger with confirmed SARS-CoV-2 infection, detected at any anatomical site by RT-PCR, between April 1 and April 24, 2020, during the initial peak of the European COVID-19 pandemic. We explored factors associated with need for intensive care unit (ICU) admission and initiation of drug treatment for COVID-19 using univariable analysis, and applied multivariable logistic regression with backwards stepwise analysis to further explore those factors significantly associated with ICU admission.Findings582 individuals with PCR-confirmed SARS-CoV-2 infection were included, with a median age of 5·0 years (IQR 0·5–12·0) and a sex ratio of 1·15 males per female. 145 (25%) had pre-existing medical conditions. 363 (62%) individuals were admitted to hospital. 48 (8%) individuals required ICU admission, 25 (4%) mechanical ventilation (median duration 7 days, IQR 2–11, range 1–34), 19 (3%) inotropic support, and one (<1%) extracorporeal membrane oxygenation. Significant risk factors for requiring ICU admission in multivariable analyses were being younger than 1 month (odds ratio 5·06, 95% CI 1·72–14·87; p=0·0035), male sex (2·12, 1·06–4·21; p=0·033), pre-existing medical conditions (3·27, 1·67–6·42; p=0·0015), and presence of lower respiratory tract infection signs or symptoms at presentation (10·46, 5·16–21·23; p<0·0001). The most frequently used drug with antiviral activity was hydroxychloroquine (40 [7%] patients), followed by remdesivir (17 [3%] patients), lopinavir–ritonavir (six [1%] patients), and oseltamivir (three [1%] patients). Immunomodulatory medication used included corticosteroids (22 [4%] patients), intravenous immunoglobulin (seven [1%] patients), tocilizumab (four [1%] patients), anakinra (three [1%] patients), and siltuximab (one [<1%] patient). Four children died (case-fatality rate 0·69%, 95% CI 0·20–1·82); at study end, the remaining 578 were alive and only 25 (4%) were still symptomatic or requiring respiratory support.InterpretationCOVID-19 is generally a mild disease in children, including infants. However, a small proportion develop severe disease requiring ICU admission and prolonged ventilation, although fatal outcome is overall rare. The data also reflect the current uncertainties regarding specific treatment options, highlighting that additional data on antiviral and immunomodulatory drugs are urgently needed.Fundingptbnet is supported by Deutsche Gesellschaft für Internationale Zusammenarbeit.

Foreign body aspiration is an important emergency and cause of morbidity and mortality in children. We present a 17-month-old boy who developed pneumonia and atelectasis a few weeks after unnoticed peanut inhalation. Despite prompt foreign body removal atelectasis persisted for three months. This case highlights the importance of timely diagnosis and treatment of foreign body aspiration.

Aim To describe epidemiological and clinical features of Croatian children and adolescents with a polymerase chain reaction (PCR)-confirmed coronavirus disease 2019. Methods Data on patients aged <= 19 years with a positive SARS-CoV-2 PCR test recorded in the period March 12-May 12 (first wave) and June 19-July 19, 2020 (second wave) were retrospectively analyzed. The periods were separated by several weeks with no incident cases. Results We analyzed data on 289 children and adolescents (6.5% of all cases; incidence rate [IR] = 3.54, 95% confidence interval [CI] 3.14-3.97/million person-days), 124 in the first wave (IR = 2.27) and 165 in the second wave (IR = 6.37): IRR second/first = 2.71 (2.13-3.44). During the first wave, the incidence was highest in infants (IR = 3.48), while during the second wave it progressively increased to IR = 7.37 in 1519-year olds. Family members were the key epidemiological contacts (72.6% cases), particularly during the first wave (95.8% vs 56.3%). Overall, 41.3% patients were asymptomatic, 25.3% in the first and 52.6% in the second wave. Age 15-19 years (vs younger) was associated with a higher (RR = 1.26, 1.02-1.54) and infection in the second wave with a lower probability (RR = 0.66, 0.53-0.81) of being symptomatic. The most common symptoms were fever, cough, and rhinorrhea. In children aged >= 7 years, headache, anosmia/ ageusia, and sore throat were also recorded. Only one child suffered a severe disease. All but 18 (7.8%) children were treated only symptomatically, and all fully recovered. Conclusion A large proportion of SARS-CoV-2 PCR-positive children/adolescents were asymptomatic. The associated disease was predominantly mild, comparably so in the first and second pandemic wave.