Vaccines Publishes Real-World Study Supporting Safety of SINOVAC's Varicella Vaccine in Children Aged 7–12

BEIJING, January 20, 2026 – A large-scale real-world study published in the peer-reviewed journal Vaccines showed that SINOVAC's live attenuated varicella vaccine (VarV) has a stable and favorable safety profile in children aged 7–12 years.

The retrospective study integrated data from two sources: the Jiangsu Provincial Immunization Information System for administered doses and the National Adverse Event Following Immunization (AEFI) Monitoring System for safety surveillance. Between July 2024 and March 2025, a total of 1,096,117 doses of VarV were administered to children aged 7 to 12 in Jiangsu Province.

Key Clinical Findings:

Low Reporting Rate and Absence of Serious Events: Across over 1.09 million administered doses, a total of 366 adverse events following immunization (AEFI) were reported, corresponding to an overall reporting rate of 33.4 per 100,000 doses. Common reactions accounted for 97.8% of reported AEFI cases, while abnormal reactions accounted for 2.2%. No vaccine-related serious adverse events were reported, and no vaccine quality issues or cluster events were identified. Overall, the observed reporting level was at the lower end of the range reported in safety monitoring of comparable varicella vaccines in China and internationally.

Predominantly Mild and Transient Reactions: Reported adverse reactions were mainly mild and transient general reactions, most commonly fever, redness at the injection site, swelling, and induration. Most cases occurred within one to three days after administration, were mild in severity, and resolved spontaneously or improved markedly. The reporting rate of abnormal reactions, including cases classified as vaccine-related or possibly vaccine-related was 0.73 per 100,000 doses. All were sporadic cases with good prognosis, and no clustering was observed.

Age-Dependent Safety Correlation: Regression analysis demonstrated a significant inverse correlation between age and the risk of adverse reactions, with reporting rates steadily decreasing from age 7 to 12. This pattern is consistent with findings from previous vaccine safety studies in children.

The findings provide important scientific support for catch-up vaccination strategies in school-aged children, varicella prevention and control in school settings, safety risk communication, and future evidence-based decisions on broader vaccine use.

SINOVAC's VarV is produced using the proprietary SV-1 human diploid cell line. The formulation does not contain gelatin, human serum albumin, or antibiotics, which supports its well-characterized safety profile.

As the only Chinese varicella vaccine to have received World Health Organization (WHO) prequalification, SINOVAC's VarV has been used in more than 20 countries and regions since launch. The findings of this real-world study provide evidence-based support for school-based catch-up vaccination strategies and public health infectious disease control.

Reference:

The full research paper, titled “Safety Evaluation of Large-Scale Administration of a Novel Human Diploid (SV-1) Cell Line-Derived Varicella Attenuated Live Vaccine in Children 7–12 Years Old”, is available at:DOI: /10.3390/vaccines14010019.