A Phase 3, Multicenter, Randomized, Controlled Trial to Evaluate Immune Equivalence and Safety of Multidose and Single-dose Formulations of Vi-DT Typhoid Conjugate Vaccine in Healthy Filipino Individuals 6 Months to 45 Years of Age

• Main Authors: Josefina Cadorna Carlos (Author), Birkneh Tilahun Tadesse (Author), Charissa Borja-Tabora (Author), Edison Alberto (Author), Michelle C. Ylade (Author), Arijit Sil (Author), Deok Ryun Kim (Author), Hyeon Seon Ahn (Author), Jae Seung Yang (Author), Ji Yeon Lee (Author), Min Soo Kim (Author), Jiwook Park (Author), Soo-Young Kwon (Author), Hun Kim (Author), Seon-Young Yang (Author), Ji-hwa Ryu (Author), Hokeun Park (Author), Jong-hoon Shin (Author), Yoonyeong Lee (Author), Jerome H. Kim (Author), Zenaida Reynoso Mojares (Author), T. Anh Wartel (Author), Sushant Sahastrabuddhe (Author)
• Format: Book
• Published: Elsevier, 2022-07-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 2666-6065; 10.1016/j.lanwpc.2022.100484
• Keywords: Typhoid fever; Vi-DT vaccine; Immune equivalence; Single dose formulation; Multidose formulation; Public aspects of medicine; RA1-1270
• Source: The Lancet Regional Health. Western Pacific, Vol 24, Iss , Pp 100484- (2022)

Summary: Trial Design: Phase 3, randomized, controlled, multicenter, equivalence trial. Methods: Recruitment of participants occurred between 04Februray2020 and 15July2020 at four centers in the Philippines: University of the East - Ramon Magsaysay Memorial Medical Center Inc., Quezon City; University of Philippines Manila - National Institute of Health, Ermita Manila; Asian Hospital and Medical Center, Metro Manila, Philippines Study; and Medical Research Unit, Tropical Disease Foundation, Makati City, Metro Manila, Philippines. Participants: 1800 adults and children 6-months to 45-years of age. Interventions: Participants received a single injection of multidose (MD) or single dose (SD) Vi-DT as test vaccines or meningococcal conjugate vaccine as a comparator. Objective: To evaluate immune equivalence of SD and MD formulations of Vi-DT, and to assess the safety of both formulations compared with comparator vaccine. Outcome Measurement: Blood draw for immunogenicity was performed at baseline prior to vaccine receipt and at four weeks after vaccination for a subset of participants to determine anti-Vi IgG geometric mean titers (GMT) and seroconversion rates. The primary outcome was comparison of anti Vi-IgG seroconversion and GMT between the two formulations of Vi-DT at 4 weeks following vaccine administration. Immune equivalence of MD and SD formulations was confirmed when the two-tailed 95% confidence interval (CI) of the GMT ratio is within [0.67, 1.5] at a two-sided significance level of 0.05. All participants were followed for safety events for six months after vaccine administration. Randomization: Participants were randomized to receive SD Vi-DT, MD Vi-DT, or meningococcal conjugate vaccines in 2.5:2.5:1 allocation ratio. Blinding: Study participants and observers were blinded to treatment assignment. Findings: Immune equivalence of SD (n=252) and MD (n=247) formulations was confirmed by anti-Vi IgG GMT ratio of 1.14 (95%CI: 0.91, 1.43) with respective GMTs in the MD and SD groups of 640.62 IU/mL (95%CI: 546.39, 751.11) and 562.57 IU/mL (95%CI: 478.80, 661.00) (p=0.259). Similarly, anti-Vi IgG seroconversion rate difference between the two formulations of ‒0.43% (95%CI: -4.42, 3.56) confirmed immune equivalence with corresponding seroconversion rates of 98.38% (95%CI: 95.91, 99.37) and 98.81% (95%CI: 96.56, 99.59) in MD and SD Vi-DT formulations, respectively (p=0.722). Both formulations of Vi-DT had a satisfactory safety profile - all five serious adverse events reported during the study were unrelated to the investigational product. Interpretation: The MD and SD formulations of Vi-DT elicited robust and equivalent immune responses following one dose vaccination, and both formulations demonstrated a favorable safety profile. Trial Registration: ClinicalTrials.gov: NCT04204096. Funding: This study was funded by the Bill & Melinda Gates Foundation (OPP 1115556).