Safety of Typhim Vi vaccine in a postmarketing observational study

Abstract

Background. Typhoid fever is endemic in many parts of the world. In the United States, nearly three quarters of all cases are contracted by persons who traveled to regions with endemic disease. Typhim Vi, a vaccine containing the purified cell surface Vi polysaccharide of the Salmonella enterica serovar Typhi, was developed to provide protection against typhoid fever. We present the results of the largest safety study of this Vi vaccine to date. Methods. This open-label, descriptive study assessed safety and reactogenicity following the Vi vaccine administration. Coadministration of other vaccines (at separate sites) was permitted, consistent with clinical practice. Participants aged 2 years or older with no known sensitivities to any vaccine component, who received the Vi vaccine, according to label directions, at a participating travel clinic, were eligible to participate. Information was collected on concurrent medications and medical conditions. The occurrence of solicited injection site reactions and systemic reactions was recorded on diary cards for 7 days following vaccination, along with any unsolicited medical events. Serious adverse events were reported for 30 days postimmunization. Results. A total of 1,204 participants (mean age: 37.2 y, range: 2-82 y, 55% female) were enrolled into the study, and 1,111 completed the 7-day follow-up. The most common solicited reactions were injection site pain [850 of 1,111 (76.5%)], tenderness [838 of 1,111 (75.4%)], and muscle aches [434 of 1,111 (39.1%)]. Fever was reported in 18 (1.6%) of 1,111 participants. Coadministration of other common travel vaccines did not affect reactogenicity profiles, except for an increase in the Vi vaccine injection site redness when two vaccines were administered in the same limb. Conclusions. The Vi vaccine was well tolerated in an unselected population, aged 2 to 82 years, presenting to a travel clinic for vaccination. © 2007 International Society of Travel Medicine.