Aaron M. Frutos, Shunte Moon, Catherine H. Bozio, Mark W. Tenforde, Matthew Biggerstaff, and Kelsey M. Sumner are with the Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, GA. Alison M. Binder and Margaret A. Dudeck are with the Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases, CDC. Andrea J. Cool, Kingsley Iyawe, and Trevor Thompson are with Booz Allen Hamilton, At