1. Immunisations and Countermeasures Division, National Infection Service, Public Health England, London, United Kingdom
2. These authors contributed equally to this article and share first authorship
3. Field Epidemiology Training Programme, National Infection Service, Public Health England, London, United Kingdom
4. Blood Safety, Hepatitis, STI and HIV Department, National Infection Service, Public Health England, London, United Kingdom
5. Blood Borne Virus Unit, Virus Reference Department, National Infection Service, Public Health England, London, United Kingdom
6. South London Health Protection Team, Public Health England, London, United Kingdom
7. South East and London Field Service, National Infection Service, Public Health England, London, United Kingdom