title: Vaccination of active component US military personnel against Salmonella Typhi.
abstract: Vaccination against Salmonella Typhi is one of the leading public health interventions reducing the risk of typhoid fever. There are two available licensed vaccines, Vivotif, oral live-attenuated, and Typhim Vi, intramuscular Vi capsular polysaccharide. The US military is a high risk travel population commonly vaccinated for S. Typhi. We describe the use of S. Typhi vaccination in this population and the acute reactogenicity profile of these vaccines.
  
  
  
  Data were obtained from the Defense Medical Surveillance System and vaccination identified between 1998 and 2011 from vaccination codes. Clinical outcomes were assessed for four weeks post vaccination. Adverse event rates and odds ratios were estimated across the two vaccine types.
  
  
  
  A total of 1.9million predominately male military personnel received 3.6 million S. Typhi vaccinations with 94.3% of vaccinees receiving the Vi capsule vaccine though variability in the vaccine administered was observed. Receipt of other vaccinations in the 6months surrounding the S. Typhi vaccine was common. Rates of nausea (195 per 100,000 vaccinations), headache (13 per 100,000 vaccinations) and fever (40 per 100,000 vaccinations) were significantly higher following Vi capsule vaccination compared to receipt of Vivotif (130, 2, 10 per 100,000 vaccinations, respectively). In contrast the rates of rash and non-infectious diarrhea (186 and 426 per 100,000 vaccinations, respectively) were increased in those receiving Vivotif compared to the Vi capsule vaccine.
  
  
  
  The US military is a major consumer of S. Typhi vaccines. The parenterally administered vaccine appears to be more amenable, though we were limited in our ability to assess the reasons for its higher usage. While we observed a higher rate of several adverse events in subjects receiving the intramuscular vaccination, the overall rate of these events was low. Future studies assessing more long-term health outcomes are warranted.
authors.affiliation: Naval Medical Research Center, Enteric Diseases Department, Silver Spring, MD, United States. Electronic address: chad.k.porter2.civ@mail.mil.
authors.forename: Chad K
authors.initials: CK
authors.lastname: Porter
authors.affiliation: Naval Medical Research Center, Enteric Diseases Department, Silver Spring, MD, United States; Henry M. Jackson Foundation, Rockville, MD, United States.
authors.forename: Tia
authors.initials: T
authors.lastname: Sorrell
authors.affiliation: Uniformed Services University, Infectious Disease Clinical Research Program, Bethesda, MD, United States.
authors.forename: Indrani
authors.initials: I
authors.lastname: Mitra
authors.affiliation: Naval Medical Research Center, Enteric Diseases Department, Silver Spring, MD, United States.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Riddle
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008889:Military Personnel; D016017:Odds Ratio; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D012485:Salmonella typhi / Q000276:immunology*; D014435:Typhoid Fever / Q000453:epidemiology / Q000517:prevention & control*; D014436:Typhoid-Paratyphoid Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D014481:United States / Q000453:epidemiology; D014611:Vaccination / Q000009:adverse effects
chemical_list: D011135:Polysaccharides, Bacterial; C072772:Ty21a typhoid vaccine; D014436:Typhoid-Paratyphoid Vaccines; C057664:Vi polysaccharide vaccine, typhoid
keywords: Salmonella Typhi; TY21a; Typhim Vi; Vaccination