Abstract
The attenuated recombinant Vibrio cholerae O1 vaccine strain CVD 103-HgR, redeveloped as PXVX0200, elicits a rapid serum vibriocidal antibody (SVA) response and protects against cholera-induced diarrhea in adult volunteer challenge trials but has not been studied in children in developed countries. We performed a phase 4, placebo-controlled, double-blind, multicenter study to assess the safety, immunogenicity, and tolerability of a single, oral dose of PXVX0200 in children and adolescents aged 6-17 years in the United States and bridged immunogenicity to adults aged 18-45 years from a separate lot consistency study. Volunteers were randomized to receive a single dose of 1 × 10(9) colony forming units (CFU) of PXVX0200 or placebo. Immunogenicity endpoints included SVA levels on days 1, 11, and 29 in volunteers aged 6-17 years and also on days 91 and 181 in volunteers aged 12-17 years. Safety was assessed by comparing solicited signs and symptoms on days 1-8, unsolicited adverse events (AEs) through day 29, and serious AEs through day 181. A total of 374 participants were enrolled, comprising 321 vaccine and 53 placebo recipients. The SVA seroconversion rates 10 days after immunization were 98.6% and 2.1% in vaccine and placebo recipients, respectively, and the vaccine seroconversion rate was non-inferior to the 93.5% rate seen in adults aged 18-45 years. Most reactogenicity was mild to moderate, and there were no vaccine-related serious AEs. The complete dose was consumed in 95.3% and 98.1% of vaccine and placebo recipients, respectively. PXVX0200 appears safe, immunogenic, and well tolerated in children and adolescents aged 6-17 years.