Live attenuated varicella vaccine (Beijing Wantai Biopharmaceutical)

Objective: To evaluate the safety and immunogenicity of a live attenuated varicella vaccine and to explore factors influencing post-vaccination varicella-zoster virus (VZV) antibody levels in healthy children aged 1-6 years in Zhejiang Province. Methods: A total of 378 healthy children aged 1-6 years were enrolled from Quzhou and Lishui in Zhejiang Province and categorized into three groups: 1-3-year-olds without prior vaccination, 4-6-year-olds without prior vaccination, and 4-6-year-olds with one prior dose of vaccination. All participants received one dose of live attenuated varicella vaccine. Serum samples were collected before and 30-35 days after vaccination, and VZV-IgG antibodies were detected using the fluorescent antibody to membrane antigen (FAMA) assay. The incidence of adverse events (AEs) within 30 days post-vaccination was assessed. Geometric mean titers (GMT), seroconversion rates (SCR), and seropositive rates (SPR) of VZV-IgG antibodies were analyzed before and after vaccination. The multiple linear stepwise regression was used to explore factors influencing post-vaccination GMT. Results: All 378 enrolled participants completed vaccination. The overall incidence of AEs was 6.61%, with no significant difference between the primary and booster immunization groups in 4-6-year-olds (6.67% vs. 6.77%, χ²<0.001, P>0.999). Among 355 participants included in the immunogenicity analysis, the pre-vaccination SPR in the 4-6-year-old group with a vaccination history was only 18.64%. The overall SCR after vaccination in children aged 1-6 years was 87.04%, and the overall GMT was 23.14, with GMTs of 22.04, 15.81, and 27.15 in the unvaccinated 1-3-year-olds, unvaccinated 4-6-year-olds, and previously vaccinated 4-6-year-olds, respectively. Multiple linear stepwise regression revealed that pre-vaccination antibody titer (standardized β=0.58, P<0.001) and prior varicella vaccination history (1 dose vs. 0 dose: standardized β=0.11, P=0.011) were positively associated with post-vaccination antibody titer. Focusing on the 4-6-year-old booster group, regression analysis indicated that post-vaccination antibody titer was positively associated with pre-vaccination antibody titer (standardized β=0.60, P<0.001), and participants from Liandu District had higher antibody titers than those from Jiangshan City (standardized β=0.16, P=0.007). Conclusion: The varicella vaccine (human diploid cell SV-1 strain) demonstrates favorable safety and immunogenicity in children aged 1-6 years. Serological evidence indicates a relatively rapid decline in VZV-IgG antibody levels after a single dose, highlighting the need for timely administration of a booster immunization.

Chickenpox outbreaks frequently occur in collective settings such as kindergartens and schools, posing a significant threat to children's physical and mental health. This study aimed to evaluate the immunogenicity and safety of the freeze-dried live attenuated varicella vaccine (VarV) developed by Beijing Minhai Biotechnology Co. LTD. in healthy participants aged 1-12 years. In this phase III, single-center, randomized, double-blind, active-controlled trial,1,200 healthy participants randomly assigned in a 1:1 ratio to receive one dose of either the test vaccine or the active control vaccine. Venous blood samples were collected before vaccination and 42 days after vaccination, and the fluorescent antibody to membrane antigen (FAMA) assay was used to detect VZV antibody. Adverse events (AEs) observed within 42 days after vaccination and serious adverse events (SAEs) within six months after vaccination were recorded. The seroconversion rates in the test and control groups were 96.79% and 96.43%, respectively, with a difference of 0.36% (95% CI, -1.76%-2.48%). The geometric mean titers (GMTs) were 61.74 and 58.04, respectively, with a difference of 1.06 (95% CI, 0.92-1.23). The lower limits of the 95% CI for the differences in seroconversion rates and GMT ratios between the two groups were greater than their respective pre-set non-inferiority margins. The overall incidence of AEs (p = .0112) in the test group was significantly lower than that in the control group. The freeze-dried live attenuated VarV developed by Beijing Minhai Biotechnology Co. LTD. demonstrated good immunogenicity and higher safety compared to the active control vaccine in healthy participants aged 1-12 years.