I.D.-B. is affiliated to the National Institute for Health and Care Research Health Protection Research Unit (NIHR HPRU) in Emerging and Zoonotic Infections at the University of Liverpool in partnership with the UK Health Security Agency (UKHSA), in collaboration with Liverpool School of Tropical Medicine and the University of Oxford. I.D.-B. is based at the University of Liverpool. The views expressed are those of the author(s) and not necessarily those of the NIHR, the Department of Health and Social Care or the UK Health Security Agency. E.C.-O. is affiliated to the NIHR HPRU in Gastrointestinal Infections at the University of Liverpool in partnership with the UKHSA, in collaboration with the University of Warwick. E.C.-O. is based at the University of Liverpool. The views expressed are those of the author(s) and not necessarily those of the NIHR, the Department of Health and Social Care or the UKHSA.