Carsetti, R

Ippolito, G

Locatelli, F

Mortari, EP

Quintarelli, C

Quinti, I

Zumla, A

English

UCL Discovery

  Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website.  Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.  Comment414 www.thelancet.com/child-adolescent   Vol 4   June 2020medication is deemed desirable, strategies for remote monitoring should be implemented.SC, PA, ES-B, TB, DB, JB, DC, DD, RWD, MDo, MF, CH, MH, EK, PS, CS, H-CS, IW, and AZ reports competing interests, which are given in full in the appendix. All other authors declare no competing interests.*Samuele Cortese, Philip Asherson, Edmund Sonuga-Barke, Tobias Banaschewski, Daniel Brandeis, Jan Buitelaar, David Coghill, David Daley, Marina Danckaerts, Ralf W Dittmann, Manfred Doepfner, Maite Ferrin, Chris Hollis, Martin Holtmann, Eric Konofal, Michel Lecendreux, Paramala Santosh, Aribert Rothenberger, César Soutullo, Hans-Christoph Steinhausen, Eric Taylor, Saskia Van der Oord, Ian Wong, Alessandro Zuddas, Emily Simonoff, for the European ADHD Guidelines Groupsamuele.cortese@soton.ac.ukCenter for Innovation in Mental Health, University of Southampton and Solent NHS Trust, Southampton SO17 1BJ, UK (SC); New York University Child Study Center, New York, NY, USA (SC); Division of Psychiatry and Applied Psychology, School of Medicine and National Institute for Health Research MindTech Mental Health MedTech Cooperative and Centre for ADHD and Neurodevelopmental Disorders Across the Lifespan, Institute of Mental Health, University of Nottingham, UK (SC, DD, CH); Social, Genetic and Developmental Psychiatry Centre (PA) and Department of Child & Adolescent Psychiatry (ES-B, PS, ET, ES), Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK; Department of Child & Adolescent Psychiatry, Aarhus University, Aarhus, Denmark (ES-B); Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany (TB, DB, RWD); Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of Psychiatry (DB, H-CS), Neuroscience Center Zurich (DB), and Center for Integrative Human Physiology (DB), University of Zurich, Zurich, Switzerland; ETH Zurich, Zurich, Switzerland (DB); Radboud University Medical Center, Nijmegen, Netherlands (JB); Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, VIC, Australia (DC); Murdoch Children’s Research Institute, Melbourne, VIC, Australia (DC); Royal Children’s Hospital, Melbourne, Melbourne, VIC, Australia (DC); Research Group of Developmental Psychiatry, Center for Developmental Psychiatry (MDa) and Clinical Psychology (SVdO), KU Leuven, Leuven, Belgium; Department of Child and Adolescent Psychiatry, University Psychiatry Hospitals-KU Leuven, Leuven, Belgium (MDa); Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Faculty of Medicine, and University Hospital Cologne, University of Cologne, Cologne, Germany (MDo); Haringey Children and Adolescent Mental Health Service, National Health Service, London, UK (MF); ReCognition Health, London, UK (MF); LWL-University Hospital for Child and Adolescent Psychiatry, Ruhr-University Bochum, Hamm, Germany (MH); Service de Physiologie Pédiatrique, Centre Pédiatrique des Pathologies Du Sommeil, Assistance Publique–Hôpitaux de Paris, Hôpital Robert Debré, Paris, France (EK, ML); Klinik für Kinder und Jugendpsychiatrie/Psychotherapie, Universitätsmedizin, Georg-August Universität Göttingen, Göttingen, Germany (AR); Louis A Fallace Department of Psychiatry and Behavioral Science, University of Texas, Houston, TX, USA (CS); Clinical Psychology and Epidemiology, Institute of Psychology, University of Basel, Basel, Switzerland (H-CS); Department of Child and Adolescent Mental Health, University of Southern Denmark, Odense, Denmark (H-CS); Child and Adolescent Mental Health Centre, Capital Region Psychiatry, Copenhagen, Denmark (H-CS); Developmental Psychology, University of Amsterdam, Amsterdam, Netherlands (SVdO); School of Pharmacy, University College London, London, UK (IW); and Department of Biomedical Sciences, University of Cagliari & Antonio Cao Paediatric Hospital, G Brotzu Hospital Trust, Cagliari, Italy (AZ)1 Royal College of Psychiatrists. PIPSIG guidelines for the use of telepsychiatry. www.rcpsych.ac.uk/docs/default-source/members/sigs/private-and-independent-practice-pipsig/pipsig-telepsychiatry-guidelines-revised-mar16.pdf (accessed April 13, 2020).2 American Association of Psychiatry. Telepsychiatry. https://www.psychiatry.org/psychiatrists/practice/telepsychiatry (accessed April 13, 2020).3 Daley D, Van Der Oord S, Ferrin M, et al. Practitioner review: current best practice in the use of parent training and other behavioural interventions in the treatment of children and adolescents with attention deficit hyperactivity disorder. J Child Psychol Psychiatry 2018; 59: 932–47.4 Dose C, Hautmann C, Buerger M, Schuermann S, Woitecki K, Doepfner M. Telephone-assisted self-help for parents of children with attention-deficit/hyperactivity disorder who have residual functional impairment despite methylphenidate treatment: a randomized controlled trial. J Child Psychol Psychiatry 2017; 58: 682–90.5 Daley D, O’Brien M. A small-scale randomized controlled trial of the self-help version of the New Forest Parent Training Programme for children with ADHD symptoms. Eur Child Adolesc Psychiatry 2013; 22: 543–52.6 Katzmann J, Hautmann C, Greimel L, et al. Behavioral and nondirective guided self-help for parents of children with externalizing behavior: mediating mechanisms in a head-to-head comparison. J Abnorm Child Psychol 2017; 45: 719–30.7 DuPaul GJ, Kern L, Belk G, et al. Face-to-face versus online behavioral parent training for young children at risk for ADHD: treatment engagement and outcomes. J Clin Child Adolesc Psychol 2018; 47 (suppl 1): 369–83.8 Cortese S, Holtmann M, Banaschewski T, et al. Practitioner review: current best practice in the management of adverse events during treatment with ADHD medications in children and adolescents. J Child Psychol Psychiatry 2013; 54: 227–46.9 Bruni O, Alonso-Alconada D, Besag F, et al. Current role of melatonin in pediatric neurology: clinical recommendations. Eur J Paediatr Neurol 2015; 19: 122–33.10 UK Medicines and Healthcare Products Regulatory Agency. Government response: ibuprofen use and coronavirus (COVID-19). March 20, 2020. https://www.gov.uk/government/news/ibuprofen-use-and-covid19coronavirus (accessed April 14, 2020).The immune system of children: the key to understanding SARS-CoV-2 susceptibility?Humanity has repeatedly faced epidemics of known and novel pathogens and the immune system has adapted to survive. Since severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new zoonotic pathogen, there is no pre-existing immunity and the whole of humanity is susceptible to infection and developing COVID-19 disease.Adults can be infected with different outcomes, from asymptomatic, mild, moderate to severe disease, and death. Children can also be infected by SARS-CoV-2, but most paediatric cases with laboratory-confirmed SARS-CoV-2 infection are mild; severe COVID-19 disease in children is rare.1Children are more vulnerable to other infections; thus, the important question arises—why are children less susceptible to COVID-19 disease compared with adults? So far, there is no evidence of a lower degree of expression or function of the SARS-CoV-2 receptor (namely ACE2) in Published Online May 6, 2020 https://doi.org/10.1016/S2352-4642(20)30135-8Commentwww.thelancet.com/child-adolescent   Vol 4   June 2020 415children. Thus, studying the innate immune system of children might be the key to understanding protection against or susceptibility to SARS-CoV-2.2During the first months of life, maternal antibodies3 protect the child from the microorganisms that the mother has encountered previously. Although water sanitation and hygiene practices have reduced epidemics and vaccines have been developed to prevent potentially lethal diseases,4 all microorganisms are new for the child. The frequent infections occurring in the first years of life serve to build the pool of memory T and B cells that will prevent reinfection or development of disease by commonly encountered pathogens.5 Thus, the paediatric immune system is prepared and fit to react to novelty, a function that might be diminished in adults and ineffective in elderly people aged 70 years or older.Although innate immunity and T cells play a crucial role in the defense against infection, antibodies also play an important role. In the SARS, Ebola, and H1N1 epidemics, convalescent plasma containing antibodies from patients who had recovered from viral infections was used for treatment at the early stage of disease. Human monoclonal antibodies obtained from cloned B cells of a convalescent SARS-Cov-2 might become candidate therapeutics.6In most cases, viral load peaks in the first week of infection and patients generate a primary immune response by days 10–14, followed by virus clearance through the action of high-affinity antibodies and T cells. The response of naive B cells to any novel infection or vaccine occurs through the germinal centre reaction and takes 2 weeks. This is a reasonable time for the response to a vaccine, but it is much too long for the response to infection. In the germinal centre,7 B cells modify their antibodies through the introduction of somatic mutations in the antigen-binding site of the immunoglobulin variable heavy chain genes. Only modified B cells that express high-affinity antibodies are selected to become memory B cells (MBCs) and plasma cells.The immune preparedness of children to any novel pathogens, including, SARS-CoV-2 might be based on several factors. First, in the early phases of infection, natural antibodies8 play a most important role. Natural antibodies, mostly of IgM isotype and generated independently of previous antigen encounters, have a broad reactivity and a variable affinity. They contain the infection during the 2 weeks necessary for production of high-affinity antibodies and MBCs9 that will clear the virus and prevent reinfection. High-affinity antibodies are expressed by switched MBCs. In humans, natural antibodies are produced by innate or IgM MBCs, a population of MBCs that is generated independently of the germinal centres and is most abundant in children.10,5 From this population of B cells, sorted from the blood of young adults never exposed to avian influenza virus, we have cloned human antibodies able to neutralise antigenically diverse H1, H2, H5, H6, H8, and H9 influenza subtypes.11 Thus, innate or IgM MBCs can bind many different unknown microorganisms.Second, children have the ability to rapidly produce natural antibodies with broad reactivity that have not yet been selected and shaped by the reaction to common environmental pathogens. Following infection, two types of MBC, CD27dull and CD27bright MBCs,12 cooperate. The two populations are related but have distinct molecular signatures and functions. CD27bright MBCs express highly mutated VH genes shaped by antigen. On stimulation, CD27bright MBCs rapidly differentiate into plasmablasts and secrete antigen-specific antibodies, mostly of switched isotype. By contrast, CD27dull MBCs are less mutated, generate few plasmablasts and secrete IgM antibodies. Innate or IgM MBCs are CD27dull. When CD27bright MBCs are used to produce plasmablasts and increase the amounts of antibody, CD27dull MBCs proliferate and rapidly reconstitute MBC numbers.12 Thus, the interrelationship between CD27dull and CD27bright MBCs might explain the resilience and rapidity of the adult immune response.Third, when a novel pathogen challenges the immune system, CD27dull MBCs might play a crucial role being capable of a more rapid reaction than naive B cells. They could immediately secrete antibodies and simultaneously enter the germinal centre reaction, where they acquire more somatic mutations and select their BCR on the basis of affinity. In infants and children, most MBCs are CD27dull and thus highly adaptable to new antigens. In contrast, in the elderly, most MBCs are CD27bright. CD27bright MBCs, being highly mutated and specific, recognise their targets but appear incapable of adaptation to new antigens.We have just started a prospective study aimed at testing our hypotheses discussed above. Our preliminary results in children suggest an early polyclonal B-cell Kateryna Kon/Science Photo Library Comment416 www.thelancet.com/child-adolescent   Vol 4   June 2020response with production of substantial numbers of plasmablasts, mostly of IgM isotype. This response is not observed in adults with severe disease (who have a depletion of the B-cell compartment). Further studies are ongoing to show the difference in the specificities of the antibodies of children and adults. In addition to antibody production, B cells also have the function to secrete cytokines. IL-10, a potent anti-inflammatory cytokine is produced by neonatal B cells, activated B cells,13 and IgA plasmablasts. Thus, the child immune response might have the double function of exerting protection and reducing immune-mediated tissue damage, in particular, in the lung.Evolution has endowed a survival advantage to children to combat known and unknown pathogens. The adult is also well protected by the balance of cells with high and low specificity. With ageing, malnutrition, immunosuppression, and co-morbid states, our immune system loses the ability to adapt to novelty. Although vaccines are the way forward, in emergency situations such as the COVID-19 pandemic, the investigation and use of immune tools that nature has endowed to children might improve management outcomes.GI is supported by the Italian Ministry of Health (Ricerca Corrente Linea 1). AZ and GI are members of the Pan-African Network on emerging and re-emerging infections and thank the European and Developing Countries Clinical Trials Partnership for support under Horizon 2020, the EU Framework Programme for Research and Innovation. AZ is in receipt of an NIHR Senior Investigator Award. RC is supported by the Italian Ministry of Health (grant RF2013-02358960). We declare no competing interests.*Rita Carsetti, Concetta Quintarelli, Isabella Quinti, Eva Piano Mortari, Alimuddin Zumla, Giuseppe Ippolito, Franco Locatellirita.carsetti@opbg.netPromoting healthy movement behaviours among children during the COVID-19 pandemicGlobal movement behaviour guidelines recommend that preschool children (aged 3–4 years) accumulate at least 180 min physical activity, engage in no more than 1 h sedentary screen time, and have 10–13 h good-quality sleep per day. For school-age children and adolescents (5–17 years), the recommendations are to participate in at least 60 min moderate-intensity to vigorous-intensity physical activity, engage in no more than 2 h sedentary recreational screen time, and have 9–11 h good-quality sleep each day.Children typically obtain their daily physical activity through active travel to school; physical education and recess; organised sports, games, and dance; active play; and spending time in playgrounds and parks. Conversely, most of their sedentary time and sleep are accumulated at home. As a result of the coronavirus disease 2019 Published Online April 29, 2020 https://doi.org/10.1016/S2352-4642(20)30131-0For movement behaviour guidelines for preschool children see https://apps.who.int/iris/handle/10665/311664B Cell Pathophysiology Unit, Immunology Research Area (RC, EPM), Diagnostic Immunology Unit, Department of Laboratories (RC), and Department of Haematology and Oncology (CQ, FL), Bambino Gesù Children’s Hospital, IRCCS, Rome; Department of Clinical Medicine and Surgery, University of Naples Federico II, Naples, Italy (CQ); Department of Molecular Medicine (IQ), Department of Paediatrics (FL), Sapienza University of Rome, Rome, Italy; Centre for Clinical Microbiology, Division of Infection and Immunity, University College London, Royal Free Hospital Campus, Division of Infection and Immunity, University College London, and NIHR Biomedical Research Centre, UCL Hospitals NHS Foundation Trust, London, UK (AZ); and National Institute for Infectious Diseases “Lazzaro Spallanzani“ IRCCS, Rome, Italy (GI)1 Shen K, Yang Y, Wang T, et al. Diagnosis, treatment, and prevention of 2019 novel coronavirus infection in children: experts’ consensus statement. World J Pediatr 2020; published online Feb 7. DOI:10.1007/s12519-020-00343-7.2 Lee P-I, Hu Y-L, Chen P-Y, Huang Y-C, Hsueh P-R. Are children less susceptible to COVID-19? J Microbiol Immunol Infect 2020; published online Feb 25. https://doi.org/10.1016/j.jmii.2020.02.011.3 Lindsey B, Kampmann B, Jones C. Maternal immunization as a strategy to decrease susceptibility to infection in newborn infants. Curr Opin Infect Dis 2013; 26: 248–53.4 Delany I, Rappuoli R, De Gregorio E. Vaccines for the 21st century. EMBO Mol Med 2014; 6: 708–20.5 Aranburu A, Piano Mortari E, Baban A, et al. Human B-cell memory is shaped by age- and tissue-specific T-independent and GC-dependent events. Eur J Immunol 2017; 47: 327–44.6 Tian X, Li C, Huang A, et al. Potent binding of 2019 novel coronavirus spike protein by a SARS coronavirus-specific human monoclonal antibody. Emerg Microbes Infect 2020; 9: 382–5.7 Victora GD, Nussenzweig MC. Germinal Centers. Annu Rev Immunol 2012; 30: 429–57.8 Holodick NE, Rodríguez-Zhurbenko N, Hernández AM. Defining Natural Antibodies. Front Immunol 2017; 8: 872.9 Ochsenbein AF, Fehr T, Lutz C, et al. Control of early viral and bacterial distribution and disease by natural antibodies. Science 1999; 286: 2156–9.10 Capolunghi F, Rosado MM, Sinibaldi M, Aranburu A, Carsetti R. Why do we need IgM memory B cells? Immunol Lett 2013; 152: 114–20.11 Throsby M, van den Brink E, Jongeneelen M, et al. Heterosubtypic neutralizing monoclonal antibodies cross-protective against H5N1 and H1N1 recovered from human IgM+ memory B cells. PLoS One 2008; 3: e3942.12 Grimsholm O, Piano Mortari E, Davydov AN, et al. The interplay between CD27dull and CD27bright B cells ensures the flexibility, stability, and resilience of human B cell memory. Cell Rep 2020; 30: 2963–77.e6.13 Mauri C, Menon M. Human regulatory B cells in health and disease: therapeutic potential. J Clin Invest 2017; 127: 772–79. 

The immune system of children: the key to understanding SARS-CoV-2 susceptibility?

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The immune system of children: the key to understanding SARS-CoV-2 susceptibility?

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