1 Emerging Pathogen Serology group, Vaccine Development and Evaluation Centre (VDEC), UK Health Security Agency, Porton Down SP4 0JG, UK.
2 Emerging Pathogen Serology group, Vaccine Development and Evaluation Centre (VDEC), UK Health Security Agency, Porton Down SP4 0JG, UK; Department of Microbiology, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
3 Emerging Pathogen Serology group, Vaccine Development and Evaluation Centre (VDEC), UK Health Security Agency, Porton Down SP4 0JG, UK. Electronic address: ashley.otter@ukhsa.gov.uk.