NAVAL BASE SAN DIEGO (Sept. 21, 2023) Hospital Corpsman 2nd Class Charlie Knight, assigned to amphibious assault ship USS Essex (LHD 2), administers a flu vaccine aboard Barracks Ship (APL-2) at Naval Base San Diego, Sept. 21, 2023. Essex is homeported in San Diego, conducting a maintenance period to upgrade and refurbish many key systems. (U.S. Navy photo by Mass Communication Specialist 3rd Class Isaak Martinez)