Immunogenicity and safety of serum-free rabies vaccine for human use with simulated post-exposure schedules: A randomized, double-blind, active-controlled phase III clinical trial

BACKGROUND: Rabies is a fatal zoonotic disease that can be effectively prevented through timely postexposure prophylaxis (PEP). Serum-free rabies vaccines may theoretically reduce risks associated with animal-derived components, and simplified PEP schedules may improve vaccination compliance and accessibility. This trial evaluated the immunogenicity and safety of Sinovac serum-free rabies vaccine administered using 5-dose and simplified 4-dose schedules. METHODS: A randomized, double-blind, active-controlled phase III clinical trial was conducted in 2000 healthy participants aged 10-60 years. Participants were randomized in a 1:1:1:1 ratio to receive Sinovac rabies vaccine according to the 5-dose Essen schedule on D0,3,7,14,28 (5-dose study group), two 4-dose schedules on D0,3,7,14 (4-dose study group 1) or D0,3,7,28 (4-dose study group 2), or a licensed rabies vaccine according to the 5-dose Essen schedule (5-dose control group). Primary endpoints were seroconversion rates (SCRs) and geometric mean concentrations (GMCs) on D14 and SCRs on D42 in susceptible participants with baseline rabies virus neutralizing antibodies (RVNA)