University of Liverpool - Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool - Department of Health Data Scienc, University of Liverpool - Institute of Infection and Global Health, University of Liverpool - Institute of Infection and Global Health, Chelsea and Westminster Hospital - Department of Neurology, Encephalitis Society, University of Liverpool, The Walton Centre NHS Foundation Trust, The Walton Centre NHS Foundation Trust - Department of Neurology, University of Liverpool, University of Liverpool - Department of Health Data Science, University of Liverpool - Institute of Infection, Veterinary and Ecological Sciences, University of Exeter - Health Economics Group, Encephalitis Society, Liverpool University Hospitals NHS Foundation Trust (LUH) - Tropical and Infectious Disease Unit, University of Liverpool - Institute of Infection, Veterinary and Ecological Sciences, University of Oxford, Independent, University of Liverpool - Department of Health Data Science and University of Liverpool - Institute of Infection and Global Health

Imperial College London, affiliation not provided to SSRN, affiliation not provided to SSRN, Universidade de Santiago de Compostela - Genetics, Vaccines, Infections and Paediatrics Research group (GENVIP), affiliation not provided to SSRN, Imperial College London - Section of Paediatric Infectious Disease, Imperial College London, Imperial College London - Department of Epidemiology and Biostatistics, affiliation not provided to SSRN, Imperial College London, University of Liverpool, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, London School of Hygiene & Tropical Medicine - Medical Research Council Unit The Gambia, Imperial College London, affiliation not provided to SSRN, Erasmus University Rotterdam (EUR) - Department of Paediatric Infectious Diseases and Immunology, affiliation not provided to SSRN, Bern University Hospital, University of Bern, Imperial College London, Radboud University Nijmegen - Section of Paediatric Infectious Diseases, NHS Foundation Trust - Department of Paediatric Immunology, Infectious Diseases & Allergy, Royal Alexandra Hospital, University of Amsterdam - Department of Pediatric Immunology, Rheumatology and Infectious Disease, affiliation not provided to SSRN, Erasmus University Rotterdam (EUR) - Department of General Paediatrics, University of Oxford - Oxford Vaccine Group, affiliation not provided to SSRN, University of Oxford - Oxford Vaccine Group, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, Ludwig Maximilian University of Munich (LMU) - Division of Paediatric Infectious Diseases, London School of Hygiene & Tropical Medicine - Department of Clinical Research, affiliation not provided to SSRN, Medical University of Graz - Department of General Paediatrics, Imperial College London, University of Liverpool - Institute of Infection, Veterinary and Ecological Sciences, Imperial College London, affiliation not provided to SSRN, affiliation not provided to SSRN, Imperial College London - Section of Paediatric Infectious Disease, Imperial College London - Section of Paediatric Infectious Disease and affiliation not provided to SSRN

Alder Hey Children's NHS Foundation Trust, University of Liverpool - Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool - Department of Biostatistics, Alder Hey Children's NHS Foundation Trust, University of Liverpool - Institute of Infection, Veterinary and Ecological Sciences, Alder Hey Children's NHS Foundation Trust - Critical Care Unit and Independent