Non-inferiority Trial of Locally Manufactured Typhoid Conjugate Vaccine 'Typhocon' in Bangladesh

This is a double blinded, randomized-controlled, non-inferiority trial of a typhoid conjugate vaccine, Typhocon (Vi- polysaccharide conjugated to diphtheria toxoid, Vi-DT), manufactured by a local company, Incepta Vaccine Limited. The vaccine will be tested among individuals from 6 months to 60 years of age residing in Mirpur area of Dhaka city. The Typbar-TCV (Vi-polysaccharide conjugated to tetanus toxoid, Vi-TT), manufactured by Bharat Biotech International Limited will be used as a reference vaccine in this study. In Phase I the Typhocon vaccine will be tested in 30 adults. Safety and immunogenicity data of the vaccine for 30 adults will be submitted to the Data Safety Monitoring Board (DSMB), IRB and Directorate General of Drug Administration (DGDA). Upon receiving approval letter, the investigators will initiate the Phase II study including 600 individuals. The Phase II study will be conducted in age de-escalation manner (6-23 months, 2-5 years, 6-17 years and 18-60 years). Equal number of participants of all age groups will be enrolled for vaccination. Blood specimens will also be collected for carrying out the clinical chemistry (complete blood count with differential for white blood count, hemoglobin, absolute neutrophil count, platelet count, serum alanine transaminase, serum creatinine) on day -7 to day -2 for screening of participants before vaccination and on day 28, postvaccination. Based on blood reports of clinical chemistry, 600 participants will be randomized in a 1:1 ratio to allocate Typhocon or Typbar-TCV vaccine. Memory aid will be used to collect solicited adverse events following vaccination (AEFI) data up to day 7. Data on unsolicited AEFI and serious adverse events (SAEs) will be collected up to 28 days after vaccination. All study update including adverse events and serious adverse events will be reported to the DSMB. Blood specimen will be obtained on day 0 before vaccination, and day 28 for carrying out Enzyme-linked Immunosorbent Assay