Clinical Trial of Enterovirus 71（EV71） Inactivated Vaccine in Children Aged 36-71 Months

This study is a randomized, double-blind, single-center, controlled phase III clinical trial in children aged 36-71 months, and bridging trial between agegroup of 6-35 and 36-71 months. The purpose of this study is to evaluate the immunogenicity and safety of the experimental EV71 vaccine in children aged 36-71 months. The primary objective of this study is to evaluate the non-inferiority of experimental EV71 vaccine compared to the control EV71 vaccine in children aged 36-71 months, and the non-inferiority of EV71 vaccine used in children aged 36-71 months compared to 6-35 months. The secondary objective is to evaluate the safety of the experimental vaccine used in children aged 36-71 months. The experimental vaccine is manufactured by Sinovac Biotech Co., Ltd, and the control vaccine is manufactured by Institute of Medical Biology Chinese Academy of Medical Sciences. 600 children aged 36-71 months will be randomly assigned in to receive the experimental vaccine or control vaccine, and 300 children aged 6-35 months will receive the experimental vaccine.

Inclusion criteria

• Healthy volunteers ≥ 2 years old;
• Proven legal identity;
• Participants or guardians of the participants should be capable of understanding the written consent form, and such form should be signed prior to enrolment.

Exclusion criteria

• Prior vaccination with EV71 vaccine;
• History of hand, foot and mouth disease;
• History of allergy to any vaccine or vaccine ingredient, asthma, serious adverse reactions to vaccination, such as urticaria, dyspnea, angioneurotic edema, abdominal pain, etc;
• Congenital malformation, developmental disorders, genetic defects, or severe malnutrition;
• Autoimmune disease or immunodeficiency/immunosuppressive;
• Severe/uncontrollable nervous system disease (epilepsy, seizures or convulsions) or mental illness;
• History of thyroidectomy, no spleen and functional spleen;
• Diagnosed coagulation function abnormal (e.g., coagulation factor deficiency, coagulation disorder, or platelet abnormalities) , or obvious bruising or coagulation disorders;
• Receipt of any of the following products:

• Any immunosuppressant, cytotoxic medicine, or inhaled corticosteroids (except corticosteroid spray for treatment of allergic rhinitis or corticosteroid treatment on surface for acute non-complicated dermatitis) within 6 month prior to study entry
• Blood products within 2 months prior to study entry
• Any other investigational products (drug or vaccine）within 30 days prior to study entry
• Any live attenuated vaccine within 14 days prior to study entry
• Any subunit vaccine or inactivated vaccine within 7 days prior to study entry;
• Acute disease or acute stage of chronic disease within 7 days prior to study entry;
• Axillary temperature > 37.0 °C;
• Any other factor that suggesting the volunteer is unsuitable for this study based on the opinions of investigators.