key: cord-1039161-uj4agjhg authors: Desmet, Stefanie; Ekinci, Esra; Wouters, Ine; Decru, Bram; Beuselinck, Kurt; Malhotra‐Kumar, Surbhi; Theeten, Heidi title: No SARS‐CoV‐2 carriage observed in children attending daycare centers during the intial weeks of the epidemic in Belgium date: 2020-12-17 journal: J Med Virol DOI: 10.1002/jmv.26689 sha: eef36237cce5dd42fe97d1464adccf5988877f59 doc_id: 1039161 cord_uid: uj4agjhg To gain knowledge about the role of young children attending daycare in the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) epidemic, a random sample of children (n = 84) aged between 6 and 30 months attending daycare in Belgium was studied shortly after the start of the epidemic (February 29th) and before the lockdown (March 18th) by performing in‐house SARS‐CoV‐2 real‐time polymerase chain reaction. No asymptomatic carriage of SARS‐CoV‐2 was detected, whereas common cold symptoms were common (51.2%). Our study shows that in Belgium, there was no sign of early introduction into daycare centers at the moment children being not yet isolated at home, although the virus was clearly circulating. It is clear that more evidence is needed to understand the actual role of young children in the transmission of SARS‐CoV‐2 and their infection risk when attending daycare. To gain knowledge about the role of young children attending daycare in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic, a random sample of children (n = 84) aged between 6 and 30 months attending daycare in Belgium was studied shortly after the start of the epidemic (February 29th) and before the lockdown (March 18th) by performing in-house SARS-CoV-2 real-time polymerase chain reaction. No asymptomatic carriage of SARS-CoV-2 was detected, whereas common cold symptoms were common (51.2%). Our study shows that in Belgium, there was no sign of early introduction into daycare centers at the moment children being not yet isolated at home, although the virus was clearly circulating. It is clear that more evidence is needed to understand the actual role of young children in the transmission of SARS-CoV-2 and their infection risk when attending daycare. after touching infected objects. 1 Most common clinical manifestations of SARS-CoV-2 are fever, dry cough, shortness of breath, and respiratory failure and vary from very mild to severe symptoms. 2 Other symptoms in children are diarrhea, nausea/vomiting, fatigue, and abdominal pain. [3] [4] [5] Recently, in the United States, England, Italy, and France, rare cases with symptoms of Kawasaki-like multisystem inflammatory syndrome were reported. [6] [7] [8] [9] Current evidence indicates that older populations are most susceptible to severe presentations of COVID-19; however, there is less knowledge about disease severity and transmission among infants and children. 10 Evidence in China suggests that the clinical symptoms of COVID-19 may be less severe in children and thus harder to recognize. 11, 12 Possible explanations could be: (1) children might have fewer opportunities for exposure to pathogens or infected patients, 11 (2) lower expression of the angiotensin-converting enzyme II (ACE2) receptor as it is indicated that ACE2 is likely the receptor for SARS-CoV-2, 13 (3) children often get respiratory infections (including coronaviruses) in the winter and might therefore have higher antibody levels than adults, 11 (4) the immune system of children is still developing and may react differently on pathogens compared to adults' immune system. 14 The lower symptomatic disease incidence in the pediatric population raises the concern that this population could be an important source of SARS-CoV-2 transmission. 12 Understanding the burden of carriage in children and the sub- 16 Due to the restricted testing at that moment, no reliable Belgian incidence rates are available for March 2020, but seroprevalence of SARS-CoV-2 IgG was 2.9% at the end of March. 16 2 | MATERIAL AND METHODS The current study was embedded in the nasopharyngeal (NP) carriage study that started in Belgium in 2016 to monitor changes in the proportions of pneumococcal serotypes in children between six and thirty months of age attending DCCs. 17 DCCs were randomly selected throughout Belgium. After written consent of at least one parent, a single NP swab (pediatric flocked swab (Copan®)) was The collected swabs were transported on dry ice and stored in 1 ml STGG (skim milk, tryptone, glucose, glycerol). In-house SARS-CoV-2 real-time PCR targeting the E gene, making use of primers adapted from Corman et al. 18 22 China reported a lower secondary attack rate to children than to adults (4% vs. 17%) in a household study. 23 Only a handful of deaths among children with COVID-19 have been reported worldwide, and generally, symptoms in children are mild. 24 Limited evidence from contact research suggests that children less frequently infect other people than do adults, although similar viral loads as in adults were observed in an unpublished German study. 25 In the Netherlands, a household study showed that the spread of SARS-CoV-2 occurs mainly between people of approximately the same age, and that patients under 20 years of age had a smaller impact on the spread of the virus compared to adults. 26 A recent review found only 9.7% pediatric index cases among 31 intrahousehold transmission clusters identified from the literature. 27 These findings were supported by data from Guangzhou. They found even lower rate of children (around 5%) as index cases in households. 28 A case study of a cluster in France showed that there was no transmission from a COVID-19-positive child to any other person after exposure to more than a hundred children. 29 In Austria, 735 students and 128 staff were in close contact with nine children and nine adult school cases; here again, no transmission from the cases to other people was observed. 30 Our study adds that in Belgium, where the epidemic was im- Characteristics of pediatric SARS-CoV-2 infection and potential evidence for persistent fecal viral shedding A pneumonia outbreak associated with a new coronavirus of probable bat origin Systematic review of COVID-19 in children shows milder cases and a better prognosis than adults Clinical manifestations of children with COVID-19: a systematic review SARS-CoV-2 infection in children: transmission dynamics and clinical characteristics COVID-19 and Kawasaki disease: novel virus and novel case Hyperinflammatory shock in children during COVID-19 pandemic An outbreak of severe Kawasaki-like disease at the Italian epicentre of the SARS-CoV-2 epidemic: an observational cohort study Kawasaki-like multisystem inflammatory syndrome in children during the covid-19 pandemic in Paris, France: prospective observational study The Novel Coronavirus Pneumonia Emergency Response Epidemiology Team. The Epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19)-China Epidemiology of COVID-19 among children in China Coronavirus disease-19 among children outside Wuhan, China (2/25/2020) SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2 and is blocked by a clinically proven protease inhibitor The possible immunological pathways for the variable immunopathogenesis of COVID-19 infections among healthy adults, elderly and children COVID-19-Epidemiologische situatie op 14 maart 2020. Sciensano Seroprevalence of IgG antibodies against SARS coronavirus 2 in Belgium: a prospective crosssectional study of residual samples How nasopharyngeal pneumococcal carriage evolved during and after a PCV13-to-PCV10 vaccination programme switch in Belgium Detection of 2019 novel coronavirus (2019-nCoV) by real-time RT-PCR Early spread of SARS-Cov-2 in the Icelandic population Suppression of COVID-19 outbreak in the municipality of Vo, Italy Coronavirus disease 2019 in children-United States Epidemiology and transmission of COVID-19 in Shenzhen China: analysis of 391 cases and 1,286 of their close contacts The characteristics of household transmission of COVID-19 Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children and adolescents: a systematic review An analysis of SARS-CoV-2 viral load by patient age. medRxiv Ministerie van Volksgezondheid, Welzijn en Sport Children are unlikely to have been the primary source of household SARS-CoV-2 infections. medRxiv Household secondary attack rate of COVID-19 and associated determinants Cluster of coronavirus disease 2019 (COVID-19) in the French Alps National Centre for Immunisation Research and Surveillance (NCIRS). 2020. COVID-19 in schools-the experience No SARS-CoV-2 carriage observed in children attending daycare centers during the intial weeks of the epidemic in Belgium The authors declare that there are no conflict of interests. All authors contributed to study design and implementation. Esra Desmet and Surbhi Malhotra-Kumar reviewed the manuscript. The data that support the findings of this study are available from the corresponding author upon reasonable request. http://orcid.org/0000-0003-1101-5681