Updated Recommendations for the Use of Typhoid Vaccine — Advisory Committee on Immunization Practices, United States, 2015

Brendan R. Jackson, MD; Shahed Iqbal, PhD; Barbara Mahon, MD

Disclosures

Morbidity and Mortality Weekly Report. 2015;64(11):305-308. 

In This Article

Typhoid Vaccines

Two typhoid vaccines are available for use in the United States: 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). A parenteral heat-phenol-inactivated whole-cell vaccine first licensed by Wyeth in 1952 and associated with high rates of fever and systemic reactions was discontinued in 2000.[6]

No efficacy studies among travelers from nonendemic areas are available for either vaccine, though a Ty21a vaccine challenge study among North American volunteers demonstrated significant protection from disease.[11,12] The two currently available vaccines have moderate efficacy in populations where typhoid is endemic. In a systematic review and meta-analysis, the estimated 2.5–3.0 year cumulative efficacy was 55% (95% confidence interval [CI] = 30%–70%) for the parenteral Vi polysaccharide vaccine and 48% (CI = 34%–58%) for the oral Ty21a vaccine, each based on a single trial.[13] A trial in Kolkata, India, of the Vi polysaccharide vaccine found a protective effectiveness of 61% (CI = 41%–75%) among all participants.[14] Studies conflict regarding the effectiveness of the Vi vaccine in young children. The trial in Kolkata, which included adults as well as children, found 80% (CI = 53%–91%) effectiveness among those 2–4 years,[14] whereas a trial in Karachi, Pakistan, which included only children 2–16 years, showed no protection among children 2–4 years.[15] Herd effects might have contributed to the high effectiveness observed among young children in the Kolkata trial. An observational study of the effectiveness of typhoid vaccination in U.S. travelers estimated 80% protection; however, this study addressed typhoid vaccination in general, not specific vaccines.[16]

Protein-conjugated Vi polysaccharide vaccines have been shown to have high efficacy in young children[17] and have been licensed in other countries,[18] but are not currently licensed or available in the United States.

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