On Mar. 27, 2015, the U.S. Centers for Disease Control and Prevention (CDC) published new Immunization Practices Advisory Committee (ACIP) recommendations for typhoid vaccination. Two typhoid vaccines were available for use in the U.S.: 1) a Vi capsular polysaccharide vaccine for parenteral use (Typhim Vi, manufactured by Sanofi Pasteur) and 2) an oral live-attenuated vaccine (Vivotif, manufactured from the Ty21a strain of Salmonella serotype Typhi by PaxVax).

The CDC also included an update on the epidemiology of enteric fever in the United States, focusing on increasing drug resistance in Salmonella enterica serotype Typhi, the cause of typhoid fever, as well as the emergence of Salmonella serotype Paratyphi A, a cause of paratyphoid fever, against which typhoid vaccines offer little or no protection.