About the Authors

Thomas R. Hird
Nicholas C. Grassly

n.grassly@imperial.ac.uk

Affiliation Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, United Kingdom

Competing Interests

NCG is a member of the WHO working group on IPV that reports to the Strategic Advisory Group of Experts (SAGE) on Immunization. Otherwise, the authors have declared that no competing interests exist.