1 Oak Ridge Institute of Science and Education (ORISE), Oak Ridge, Tennessee, USA.
2 Battelle Memorial Institute, Atlanta, Georgia, USA.
3 Influenza Division, National Center for Immunization and Respiratory Diseases (NCIRD), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA.
4 Influenza Division, National Center for Immunization and Respiratory Diseases (NCIRD), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA. fzq9@cdc.gov.