1 From the *Paediatric Infectious Diseases Research Group, St George's University of London, London, United Kingdom; †PENTA Foundation, Padova, Italy; ‡Department of Paediatrics, Southampton Children's Hospital, Southampton, Hampshire, United Kingdom; §Department of Paediatric Infectious Diseases, Alder Hey Children's NHS Foundation Trust, Liverpool, United Kingdom; and ¶Institute of Infection & Global Health, University of Liverpool, Liverpool, United Kingdom.