Safety and immunogenicity of Bio Pox™, a live varicella vaccine (Oka strain) in Indian children: A comparative multicentric, randomized phase II/III clinical trial

Varicella or chickenpox is a highly contagious disease with a high secondary attack rate. Almost 30% of Indian adolescents lack protective antibodies against varicella, emphasizing the need of routine varicella immunization. The Oka VZV is a well-established, safe and efficacious vaccine strain that is highly immunogenic and produces lifelong protective immunity. The present multicentric, open label, randomized, controlled Phase II/III study, compared the Bio Pox (TM) (indigenous investigational vaccine) with a licensed vaccine, Varivax (TM)([a]), for its safety and immunogenicity profile in 252 healthy subjects in the age group of 1-12 y (cohort I: 6-12 years, II: 1-6 years) in 3 tertiary medical institutions. Antibodies were measured by VZV Glycoprotein Enzyme Linked Immunoassay (IgG ELISA) kit. Seroconversion percentage in children having pre-vaccination anti VZV IgG titer < 10 mIU/mL (< 5 gp ELISA units/mL) were 80% for Bio Pox (TM) and 77% for Varivax (TM) (p = 0.692). The seroconversion rate in the group receiving Bio Pox (TM) was non-inferior to the group that received Varivax (TM). There were mild local reactions for both the vaccines; none of the patient had fever or required hospitalization or medication. The Bio Pox (TM) was found to be safe and immunogenic in children against VZV infection.