As part of a phase 4, randomized, double-blind, placebo-controlled trial to assess the immunogenicity and safety of PXVX0200 in children and adolescents aged 2–17 years, a subset of 73 adolescent subjects aged 12–17 years was followed up for 2 years after vaccination and had blood collected for antibody assays on days 1, 11, 29, 91, 181, 365, 547, and 730. Endpoints included serum vibriocidal antibody (SVA) seroconversion, defined as a 4-fold or greater rise in antibody titer over baseline; geometric mean titers (GMTs); and geometric mean fold increase (GMFI) over baseline. Serum vibriocidal antibody seroconversion persisted in most subjects, with a rate of 64.5% noted at day 730. Geometric mean titers and GMFI both peaked at day 11 and remained greater than baseline at all time points, including day 730. Vaccination with PXVX0200 produces an immune response which persists for at least 2 years in adolescents aged 12–17 years.
Address correspondence to James M. McCarty, Stanford University School of Medicine, 291 Campus Dr., Stanford, CA 94305. E-mail: firstname.lastname@example.org
Authors’ addresses: James M. McCarty, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, E-mail: email@example.com. David Cassie, Clinical Research, Emergent BioSolutions Canada, Inc., Winnipeg, Canada, E-mail: firstname.lastname@example.org. Lis Bedell and Michael D. Lock, Department of Biostatistics, Emergent Travel Health, Inc., Redwood City, CA, E-mails: email@example.com and firstname.lastname@example.org. Sean Bennett, Clinical Development, Emergent Travel Health, Inc., Redwood City, CA, E-mail: email@example.com.