Safety of a Second Dose of Biken's Varicella Vaccine

Inclusion criteria

• Aged 4 to 6 years on the day of inclusion.
• Informed consent form signed by the parent(s) or legal guardian and by an independent witness.
• Subject and parent/guardian able to attend all scheduled visits and comply with all trial procedures.
• Written documentation of receipt of a first dose of Varicella Biken vaccine more than 3 months before inclusion.

Exclusion criteria

• Participation in another clinical trial investigating a vaccine, drug, medical device, or a medical procedure in the 4 weeks preceding the trial vaccination.
• Planned participation in another clinical trial during the present trial period.
• Known or suspected congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term systemic corticosteroids therapy.
• Known systemic hypersensitivity to any of the vaccine components or history of a life-threatening reaction to the trial vaccine or to a vaccine containing any of the same substances.
• Chronic illness, at a stage that could interfere with trial conduct or completion, in the opinion of the investigator.
• Receipt of any vaccine in the 4 weeks preceding the trial vaccination;
• Planned receipt of any vaccine in the 4 weeks following the trial vaccination.
• Known Human Immunodeficiency Virus (HIV), Hepatitis B surface antigen, or Hepatitis C seropositivity.
• History of varicella infection (confirmed either clinically, serologically or microbiologically).
• Previous vaccination against varicella disease with a vaccine different from Varicella Biken vaccine.
• Febrile illness (temperature ≥ 37.5°C) or moderate or severe acute illness/infection on the day of vaccination, according to investigator judgment.