University of Edinburgh, University College London - Great Ormond Street Institute of Child Health, University College London - Great Ormond Street Institute of Child Health, University College London - Great Ormond Street Institute of Child Health, University of Leicester, University College London - Great Ormond Street Institute of Child Health, Public Health England - Immunisation and Countermeasures Division, University College London - Great Ormond Street Institute of Child Health, University College London - Great Ormond Street Institute of Child Health and University of Edinburgh - Department of Child Life and Health