A Study Published in the International Journal of Infectious Diseases Supports Co-administration of SINOVAC's Varicella and Trivalent Influenza Vaccines in Children Aged 7–12

BEIJING, January 20, 2026 – Co-administration of SINOVAC’s live attenuated varicella vaccine (VarV) and trivalent inactivated influenza vaccine (Anflu^®) was shown to be safe and immunogenic in in healthy children aged 7 to 12 years, with immune responses non-inferior to those induced by separate administration, according to a study published in the International Journal of Infectious Diseases. The findings provide scientific support for optimizing pediatric immunization strategies, improving vaccination efficiency, and strengthening the joint prevention and control of infectious diseases in school settings.

The Phase IV randomized, open-label, controlled trial was conducted in Jiangsu Province and enrolled 899 healthy volunteer subjects aged 7 to 12 years. Participants were randomly assigned in a 1:1:1 ratio to receive VarV-alone, the TIV-alone, or both vaccines concurrently at separate injection sites. Immunogenicity was evaluated 30 days after vaccination, and safety was monitored for 30 days post-vaccination.

Key Clinical Findings:

Non-inferior Immunogenicity and No Interference: Co-administration did not interfere with the immune response to either vaccine. For VarV, seropositive rates (SPRs) exceeded 98% in both the co-administration group and the VarV-alone group, while seroconversion rates (SCRs) were about 90%. No statistically significant difference was observed in geometric mean titers (GMTs), meeting the non-inferiority criterion. For TIV, seroprotection rates against H1N1, H3N2, and B/Victoria were all 94% or higher in both the co-administration group and the TIV-alone group, while SCRs ranged from 72% to 94%. No statistically significant difference was observed in GMTs, and the non-inferiority criterion was met.

Favorable Safety Profile: The incidence of adverse reactions did not differ significantly between the co-administration group and the vaccine-alone groups. The overall adverse event rate was 8.35%, and the rate of vaccine-related adverse reaction rate was 3.67%. Most adverse reactions were mild and transient, including injection-site pain, redness, swelling, low-grade fever, and fatigue. No vaccine-related serious adverse events (SAEs) were reported.

Product Background

SINOVAC's VarV is the first varicella vaccine from China to receive World Health Organization (WHO) prequalification, and the only varicella vaccine developed and manufactured in China to include Phase 3 clinical efficacy data in its official prescribing information. It has been used in more than 20 countries and regions worldwide.

Anflu^®, the first preservative-free split influenza vaccine developed in China, was selected as the exclusive supplier for Chile's national influenza immunization program for both the 2025 and 2026 seasons, reflecting international recognition of its safety and effectiveness.

Reference:

The full research paper, titled "Immunogenicity and Safety of Varicella Vaccine Co-administered with Seasonal Influenza Vaccine in Healthy Children Aged 7-12 Years in China", is available at: https://doi.org/10.1016/j.ijid.2025.108212.